Search

OBJECTIVE: Studies on prenatal testing for Down syndrome (trisomy 21), trisomy 18, and trisomy 13 by massively parallel shotgun sequencing (MPSS) of circulating cell free DNA have been, for the most part, limited to singleton pregnancies. If MPSS testing is offered clinically, it is important to know if these trisomies will also be identified in multiple pregnancies. METHOD: Among a cohort of 4664 high-risk pregnancies, maternal plasma samples were tested from 25 twin pregnancies (17 euploid, five discordant and two concordant for Down syndrome; one discordant for trisomy 13) and two euploid triplet pregnancies [Correction made here after initial online publication.]. Results were corrected for GC content bias. For each target chromosome (21, 18, and 13), z-scores of 3 or higher were considered consistent with trisomy. RESULTS: Seven twin pregnancies with Down syndrome, one with trisomy 13, and all 17 twin euploid pregnancies were correctly classified [detection rate 100%, 95% confidence interval (CI) 59%-100%, false positive rate 0%, 95% CI 0%-19.5%], as were the two triplet euploid pregnancies. CONCLUSION: Although study size is limited, the underlying biology combined with the present data provide evidence that MPSS testing can be reliably used as a secondary screening test for Down syndrome in women with high-risk twin gestations. © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Objective To explore the clinical validity of the new Access® pregnancy-associated plasma protein-A (PAPP-A) assay for Down's syndrome screening. Setting Academic hospital. Method Residual serum samples (n = 416) received for routine first trimester Down's syndrome screening (10--13 weeks) were retrieved from freezer storage and tested using two PAPP-A immunoassay methods. The new Access® assay was specifically compared, on a subset of these samples (n = 194), with an assay proven to give acceptable Down's syndrome screening performance, the PerkinElmer (PE) AutoDELFIA method. Access® PAPP-A levels were examined in relation to gestational age and maternal weight, and were compared with the PE method by regression and Bland-Altman analyses. Results Access® PAPP-A assay results were highly correlated with the PE AutoDELFIA method (r = 0.97). PAPP-A levels obtained using the Access® assay increased with advancing gestational age and were inversely related to maternal weight, as expected. The distribution of multiples of the median (MoM) values fit a log Gaussian distribution and the standard deviation of the log MoM (0.2331) matched published estimates. PAPP-A MoM levels in Down's syndrome pregnancies (n = 6, median 0.30) showed the expected reduction. Conclusion Using an appropriate gestational age-specific median equation, the Access® PAPP-A assay is expected to perform acceptably in first trimester Down's syndrome screening. [ABSTRACT FROM AUTHOR]

Prenatal diagnosis of Down syndrome is widely available, but the determination of which patients should undergo prenatal diagnosis is changing. With the recent acceptance of first-trimester and integrated screening as a part of routine clinical practice, there are now a variety of accepted screening protocols for Down syndrome and other aneuploidies. These choices can be confusing both to both patients and providers. The following discussion is meant to outline the various options in prenatal screening, and their individual advantages and disadvantages. [ABSTRACT FROM AUTHOR]

Objective: To examine the hypothesis that early second trimester amniotic fluid (AF) insulin concentration is elevated and later fetal growth is augmented in gravidas demonstrating later oral glucose intolerance.Research Design and Methods: In this prospective observational cohort study, AF was sampled at 14-20 weeks' gestation in 247 subjects, and 1-h 50-g oral glucose challenge tests (GCTs) were performed at > or = 24 weeks. AF insulin was assayed by an automated immuno-chemiluminometric assay (8). Macrosomia was defined as birth weight above the 90th centile.Results: AF insulin concentration (range 1.4-44.5 pmol/l) correlated positively with gestational age and maternal weight. A logistic regression analysis, adjusted for maternal age and midpregnancy weight, showed increased AF insulin multiples of gestational age-specific medians to be associated with subsequently diagnosed gestational diabetes mellitus (GDM) (OR 1.9, CI 1.3-2.4, P = 0.029). Among 60 subjects with GCT values > 7.2 mmol/l, each unit increase in AF insulin multiple of median (MOM) was associated with a threefold increase in fetal macrosomia incidence (3.1, 1.3-4.9, P = 0.048).Conclusions: An elevated AF insulin concentration at 14-20 weeks' gestation is associated with subsequently documented maternal glucose intolerance. Among gravidas with GCT values > 7.2 mmol/l, elevated early AF insulin concentration is associated with fetal macrosomia. Maternal glucose intolerance may affect fetal insulin production before 20 weeks' gestation. [ABSTRACT FROM AUTHOR]

Maternal plasma contains circulating cell-free DNA fragments originating from both the mother and the placenta. The proportion derived from the placenta is known as the fetal fraction. When measured between 10 and 20 gestational weeks, the average fetal fraction in the maternal plasma is 10% to 15% but can range from under 3% to over 30%. Screening performance using next-generation sequencing of circulating cell-free DNA is better with increasing fetal fraction and, generally, samples whose values are less than 3% or 4% are unsuitable. Three examples of the clinical impact of fetal fraction are discussed. First, the distribution of test results for Down syndrome pregnancies improves as fetal fraction increases, and this can be exploited in reporting patient results. Second, the strongest factor associated with fetal fraction is maternal weight; the false negative rate and rate of low fetal fractions are highest for women with high maternal weights. Third, in a mosaic, the degree of mosaicism will impact the performance of the test because it will reduce the effective fetal fraction. By understanding these aspects of the role of fetal fraction in maternal plasma DNA testing for aneuploidy, we can better appreciate the power and the limitations of this impressive new methodology., (© 2013 John Wiley & Sons, Ltd.)

Objective: Whole-genome sequencing of circulating cell free (ccf) DNA from maternal plasma has enabled noninvasive prenatal testing for common autosomal aneuploidies. The purpose of this study was to extend the detection to include common sex chromosome aneuploidies (SCAs): [47,XXX], [45,X], [47,XXY], and [47,XYY] syndromes., Method: Massively parallel sequencing was performed on ccf DNA isolated from the plasma of 1564 pregnant women with known fetal karyotype. A classification algorithm for SCA detection was constructed and trained on this cohort. Another study of 411 maternal samples from women with blinded-to-laboratory fetal karyotypes was then performed to determine the accuracy of the classification algorithm., Results: In the training cohort, the new algorithm had a detection rate (DR) of 100% (95%CI: 82.3%, 100%), a false positive rate (FPR) of 0.1% (95%CI: 0%, 0.3%), and nonreportable rate of 6% (95%CI: 4.9%, 7.4%) for SCA determination. The blinded validation yielded similar results: DR of 96.2% (95%CI: 78.4%, 99.8%), FPR of 0.3% (95%CI: 0%, 1.8%), and nonreportable rate of 5% (95%CI: 3.2%, 7.7%) for SCA determination, Conclusion: Noninvasive prenatal identification of the most common sex chromosome aneuploidies is possible using ccf DNA and massively parallel sequencing with a high DR and a low FPR., (© 2013 John Wiley & Sons, Ltd.)

Background: Among euthyroid pregnant women in a large clinical trial, free thyroxine (FT4) measurements below the 2.5th centile were associated with a 17 lb higher weight (2.9 kg/m(2)) than in the overall study population. We explore this relationship further., Methods: Among 9351 women with second trimester thyrotropin (TSH) measurements between 1st and 98th centiles, we examine: (i) the weight/FT4 relationship; (ii) percentages of women in three weight categories at each FT4 decile; (iii) FT4 concentrations in three weight categories at each TSH decile; and (iv) impact of adjusting FT4 for weight--in the reference group and in 190 additional women with elevated TSH measurements., Results: FT4 values decrease steadily as weight increases (p<0.0001 by ANOVA) among women in the reference group (TSH 0.05-3.8 IU/L). TSH follows no consistent pattern with weight. When stratified into weight tertiles, 48% of women at the lowest FT4 decile are heavy; the percentage decreases steadily to 22% at the highest FT4 decile. Median FT4 is lowest in heaviest women regardless of the TSH level. In the reference group, weight adjustment reduces overall variance by 2.9%. Fewer FT4 measurements are at either extreme (below the 5th FT4 centile: 4.8% before adjustment, 4.7% after adjustment; above the 95th FT4 centile: 5.0% and 4.7%, respectively). Adjustment places more light weight women and fewer heavy women below the 5th FT4 centile; the converse above the 95th centile. Between TSH 3.8 and 5 IU/L, the FT4 percentage below the 5th FT4 centile is not elevated (3.8% before adjustment, 3.1% after adjustment). Percentage of FT4 values above the 95th centile, however, is lower (1.5% before adjustment, 0.8% after adjustment). Above TSH 5 IU/L, 25% of women have FT4 values below the 5th FT4 centile; weight adjustment raises this to 30%; no FT4 values remain above the 95th FT4 centile., Conclusions: During early pregnancy, TSH values are not associated with weight, unlike nonpregnant adults. Lower average FT4 values among heavy women at all TSH deciles partially explain interindividual differences in FT4 reference ranges. The continuous reciprocal relationship between weight and FT4 explains lower FT4 with higher weight. Weight adjustment refines FT4 interpretation.

Background: Circulating cell-free (ccf) fetal DNA comprises 3-20% of all the cell-free DNA present in maternal plasma. Numerous research and clinical studies have described the analysis of ccf DNA using next generation sequencing for the detection of fetal aneuploidies with high sensitivity and specificity. We sought to extend the utility of this approach by assessing semi-automated library preparation, higher sample multiplexing during sequencing, and improved bioinformatic tools to enable a higher throughput, more efficient assay while maintaining or improving clinical performance., Methods: Whole blood (10mL) was collected from pregnant female donors and plasma separated using centrifugation. Ccf DNA was extracted using column-based methods. Libraries were prepared using an optimized semi-automated library preparation method and sequenced on an Illumina HiSeq2000 sequencer in a 12-plex format. Z-scores were calculated for affected chromosomes using a robust method after normalization and genomic segment filtering. Classification was based upon a standard normal transformed cutoff value of z = 3 for chromosome 21 and z = 3.95 for chromosomes 18 and 13., Results: Two parallel assay development studies using a total of more than 1900 ccf DNA samples were performed to evaluate the technical feasibility of automating library preparation and increasing the sample multiplexing level. These processes were subsequently combined and a study of 1587 samples was completed to verify the stability of the process-optimized assay. Finally, an unblinded clinical evaluation of 1269 euploid and aneuploid samples utilizing this high-throughput assay coupled to improved bioinformatic procedures was performed. We were able to correctly detect all aneuploid cases with extremely low false positive rates of 0.09%, <0.01%, and 0.08% for trisomies 21, 18, and 13, respectively., Conclusions: These data suggest that the developed laboratory methods in concert with improved bioinformatic approaches enable higher sample throughput while maintaining high classification accuracy.

Objective: To compare maternal plasma with serum for measuring markers currently used in first and second trimester screening for Down's syndrome., Setting: A laboratory-based investigation of two sample types in assays used in prenatal screening for Down's syndrome., Methods: A paired data-set included both plasma and serum from 101 pregnant women. A nested case/control data-set included only plasma samples from 34 first and 23 second trimester Down's syndrome pregnancies, each matched with six euploid controls. Analyte levels were measured and converted to multiples of the median (MoM)., Results: In the paired data-set, each of the five analytes (alphafetoprotein, unconjugated estriol, human chorionic gonadotropin, inhibin-A and pregnancy-associated plasma protein A) in serum and plasma was highly correlated (r > 0.970) and after conversion to MoM, the resulting distributions were equivalent (P > 0.7). In the matched data-set, plasma-based median MoM levels in cases were consistent with the published serum counterparts for all markers., Conclusions: This study provides strong evidence that current serum-based prenatal screening can be performed equally well using plasma samples. This may prove useful, especially if secondary screening using a DNA-based test requires maternal plasma.

Purpose: To determine whether maternal plasma cell-free DNA sequencing can effectively identify trisomy 18 and 13., Methods: Sixty-two pregnancies with trisomy 18 and 12 with trisomy 13 were selected from a cohort of 4,664 pregnancies along with matched euploid controls (including 212 additional Down syndrome and matched controls already reported), and their samples tested using a laboratory-developed, next-generation sequencing test. Interpretation of the results for chromosome 18 and 13 included adjustment for CG content bias., Results: Among the 99.1% of samples interpreted (1,971/1,988), observed trisomy 18 and 13 detection rates were 100% (59/59) and 91.7% (11/12) at false-positive rates of 0.28% and 0.97%, respectively. Among the 17 samples without an interpretation, three were trisomy 18. If z-score cutoffs for trisomy 18 and 13 were raised slightly, the overall false-positive rates for the three aneuploidies could be as low as 0.1% (2/1,688) at an overall detection rate of 98.9% (280/283) for common aneuploidies. An independent academic laboratory confirmed performance in a subset., Conclusion: Among high-risk pregnancies, sequencing circulating cell-free DNA detects nearly all cases of Down syndrome, trisomy 18, and trisomy 13, at a low false-positive rate. This can potentially reduce invasive diagnostic procedures and related fetal losses by 95%. Evidence supports clinical testing for these aneuploidies.

Purpose: Prenatal screening for Down syndrome has improved, but the number of resulting invasive diagnostic procedures remains problematic. Measurement of circulating cell-free DNA in maternal plasma might offer improvement., Methods: A blinded, nested case-control study was designed within a cohort of 4664 pregnancies at high risk for Down syndrome. Fetal karyotyping was compared with an internally validated, laboratory-developed test based on next-generation sequencing in 212 Down syndrome and 1484 matched euploid pregnancies. None had been previously tested. Primary testing occurred at a CLIA-certified commercial laboratory, with cross validation by a CLIA-certified university laboratory., Results: Down syndrome detection rate was 98.6% (209/212), the false-positive rate was 0.20% (3/1471), and the testing failed in 13 pregnancies (0.8%); all were euploid. Before unblinding, the primary testing laboratory also reported multiple alternative interpretations. Adjusting chromosome 21 counts for guanine cytosine base content had the largest impact on improving performance., Conclusion: When applied to high-risk pregnancies, measuring maternal plasma DNA detects nearly all cases of Down syndrome at a very low false-positive rate. This method can substantially reduce the need for invasive diagnostic procedures and attendant procedure-related fetal losses. Although implementation issues need to be addressed, the evidence supports introducing this testing on a clinical basis.

Objective: Measure serum PTH and 25(OH)D in a cross-sectional sample of pregnant women at 11th through 13th weeks' gestation to examine vitamin D status and consider implications., Design: Observational: we retrieved residual sera stored at -20 °C after routine first trimester Down's syndrome screening, distributed over 12 months., Patients: 430 African American women and 586 Caucasian women., Measurements: PTH and 25-hydroxy vitamin D [25(OH)D] immunoassays., Results: PTH medians were: 1·33 pmol/l (African American women); 1·20 pmol/l (Caucasian women) (t = 0·43, P = 0·7). Concentrations were highest in winter and decreased significantly in spring, fall, and summer. There was a direct PTH/weight relationship in Caucasian (t = 3·12, P < 0·002), but not African American women (t = 1·34, P = 0·18). Median 25(OH)D concentrations were 47·5 nmol/l (African American women) and 65 nmol/l (Caucasian women) (t = 13·7, P < 0·001). Concentrations were lowest in winter and rose significantly in spring, fall, and summer. Reciprocal 25(OH)D/weight relationships existed for both racial groups (t =-4·31 P < 0·001; t = 4·54, P < 0·001, respectively). Among 68 Caucasian women who smoked, median PTH and 25(OH)D concentrations were somewhat lower (P = ns). In separate regression models with PTH and 25(OH)D [dependent variables] and season, weight and smoking [independent variables], the only qualifying interactive term was in the Caucasian PTH model (season*1/weight). A regression model applied to adjusted scatter plots of PTH vs 25(OH)D indicated a weak relationship., Conclusions: The PTH/25(OH)D relationship is weaker during early pregnancy than in non-pregnant adults, making it unreliable for estimating vitamin D sufficiency. A suitable reference point for sufficiency might be the maternal 25(OH)D level considered sufficient for adequate transfer to neonates., (© 2011 Blackwell Publishing Ltd.)

Objectives: To examine the effects of smoking on first and second trimester screening markers and to determine the overall impact of these effects on Down syndrome and trisomy 18 risks in first trimester combined, second trimester quadruple and integrated tests., Methods: Examination of screening records at Women and Infants Hospital during 2006-2008. First trimester pregnancy-associated plasma protein-A (PAPP-A), beta-human chorionic gonadotrophin (hCG) and nuchal translucency and second trimester alpha-fetoprotein (AFP), unconjugated estriol (uE3), hCG and inhibin A (inhA) multiple of the median (MoM) values were extracted from the database along with risk results, smoking status and relevant demographic information., Results: Smoking led to significantly reduced median levels of first trimester PAPP-A (0.89 MoM) and hCG (0.80 MoM), reduced second trimester uE3 (0.96 MoM) and hCG (0.84 MoM), and increased AFP (1.03 MoM) and inhA (1.39 MoM). After accounting for the differences in age between groups, smokers had higher Down syndrome screen positive rates for the second trimester quadruple test, but not for first trimester combined or integrated tests. Screen positive rates for trisomy 18 were markedly increased in smokers relative to age-matched non-smokers when using first trimester combined or integrated tests., Conclusion: Smoking leads to increased screen positive rates, especially for trisomy 18 using combined or integrated tests., (Copyright © 2011 John Wiley & Sons, Ltd.)

Objective: Decreased second trimester levels of maternal serum alpha-fetoprotein (MSAFP) have been reported in women with pregestational diabetes leading some laboratories to use a correction factor. The aim of this study is to determine if MSAFP levels in pregnant women with diabetes managed on oral antidiabetic agents is lower than non-diabetic controls and require adjustment similar to those on insulin., Study Design: We performed a nested case/control study of an existing dataset using women with pregestational diabetes who had routine MSAFP values available., Results: Before adjusting the MSAFP value for weight, both the diabetic patients who used insulin (n = 68) and those who used oral antidiabetic agents (n = 37) showed a non-significant trend toward a lower multiples of the median (MoM) as compared with controls (n = 244). After converting the raw MSAFP values to race-adjusted MoM and adjusting for weight, the median MSAFP MoM for women taking insulin (1.01) versus those on oral antidiabetic agents (1.00) were essentially the same. Furthermore, both of the diabetic groups were virtually identical to non-diabetic controls., Conclusions: In our study, women with pregestational diabetes managed on either insulin or oral antidiabetic agents had weight-adjusted MSAFP MoM levels equivalent to those in control pregnancies and did not require a correction factor., (Copyright © 2011 John Wiley & Sons, Ltd.)

Objective: To estimate the relationship between thyroid antibodies and placental abruption., Methods: This cohort study assesses thyroperoxidase and thyroglobulin antibodies in relation to placental abruption among 10,062 women with singleton viable pregnancies (from the First and Second Trimester Risk of Aneuploidy [FaSTER] trial). A thyroperoxidase antibody cutoff of 50 international units/mL is used for comparison with published data from another cohort., Results: Women with elevated thyroperoxidase antibody levels in the first and second trimesters have a higher rate of placental abruption than antibody-negative women. This relationship is less strong in the first trimester (1.51% compared with 0.83%; odds ratio [OR], 1.83; 95% confidence interval [CI], 0.99-3.37) than in the second trimester (1.78% compared with 0.82%; OR, 2.20; 95% CI, 1.21-3.99). A similar, but weaker, relationship is present for thyroglobulin antibodies. Sixty-four of 782 thyroperoxidase antibody-positive pregnancies without abruption become negative by the second trimester; one pregnancy with abruption becomes antibody-positive. Odds ratios for pregnancies with both thyroperoxidase and thyroglobulin antibody elevations are also higher (first trimester: OR, 2.10; 95% CI, 0.91-4.86; second trimester: OR, 2.73; 95% CI, 1.17-6.33)., Conclusion: The present data confirm an association between thyroid antibody elevations and placental abruption described in a recent report. These findings, however, do not provide support for recommending routine testing for thyroid antibodies during pregnancy., Level of Evidence: II.

Objective: To further evaluate the relationship between thyroid antibodies and preterm births., Methods: This is a prospective study of pregnancy outcome and demographic data combined with retrospective measurement of thyroperoxidase and thyroglobulin antibodies. Sera were obtained at 11-13 and 15-18 weeks of gestation from 10,062 women with singleton viable pregnancies (a subset from the First- and Second-Trimester Risk of Aneuploidy [FaSTER] trial)., Results: Women with elevated levels of thyroperoxidase, thyroglobulin antibodies, or both in the first trimester have a higher rate of preterm delivery before 37 weeks of gestation than antibody-negative women (7.5% compared with 6.4%, odds ratio [OR] 1.18; 95% confidence interval [CI] 0.95-1.46). This is also the case for very preterm delivery before 32 weeks of gestation (1.2% compared with 0.7%, OR 1.70; 95% CI 0.98-2.94). Preterm premature rupture of membranes is also increased (2.0% compared with 1.2%, OR 1.67; 95% CI 1.05-2.44). These associations are less strong for second-trimester antibody measurements., Conclusion: The present data do not confirm strong associations between thyroid antibody elevations and preterm birth found in three of five previously published reports. Preterm premature rupture of membranes appears to contribute to the thyroid antibody-associated early deliveries, possibly as a result of inflammation., Level of Evidence: II.

Objective: To examine serum markers measured in the second trimester to identify women who subsequently develop preeclampsia., Methods: Clinically defined preeclampsia was confirmed in 45 women who had provided a serum sample as part of Down syndrome screening. Preeclampsia was categorized as mild or severe, as well as early (<32 weeks) or late onset. Each case was matched with five controls based on gestational age and date of serum collection. Stored sera were retrieved and tested for inhibin A, soluble vascular endothelial growth factor receptor 1 (sVEGF R1), placental growth factor (PlGF), and endoglin. Results were converted to multiples of the median (MoM) and compared in case and control pregnancies. Univariate analysis was used to identify the strongest markers, which were then used in a multivariate model., Results: Inhibin A, PlGF, and endoglin were consistently associated with preeclampsia, especially for early onset disease. A multivariate model using the three markers could identify 50% of the pregnancies with early onset preeclampsia with a 2% false positive rate., Conclusion: The levels of inhibin A, PlGF, and endoglin in the second trimester can be combined using a predictive model to provide individualized risk estimates for early onset preeclampsia.

This statement is intended to augment the current general ACMG Standards and Guidelines for Clinical Genetics Laboratories and to address guidelines specific to first-trimester screening for Down syndrome. The aim is to provide the laboratory the necessary information to ensure accurate and reliable Down syndrome screening results given a screening protocol (e.g., combined first trimester and integrated testing). Information about various test combinations and their expected performance are provided, but other issues such as availability of reagents, patient interest in early test results, access to open neural tube defect screening, and availability of chorionic villus sampling are all contextual factors in deciding which screening protocol(s) will be selected by individual health care providers. Individual laboratories are responsible for meeting the quality assurance standards described by the Clinical Laboratory Improvement Act, the College of American Pathologists, and other regulatory agencies, with respect to appropriate sample documentation, assay validation, general proficiency, and quality control measures. These guidelines address first-trimester screening that includes ultrasound measurement and interpretation of nuchal translucency thickness and protocols that combine markers from both the first and second trimesters. Laboratories can use their professional judgment to make modification or additions.

Objective: To evaluate nuchal translucency measurement quality assurance techniques in a large-scale study., Methods: From 1999 to 2001, unselected patients with singleton gestations between 10 + 3 weeks and 13 + 6 weeks were recruited from 15 centers. Sonographic nuchal translucency measurement was performed by trained technicians. Four levels of quality assurance were employed: (1) a standardized protocol utilized by each sonographer; (2) local-image review by a second sonographer; (3) central-image scoring by a single physician; and (4) epidemiological monitoring of all accepted nuchal translucency measurements cross-sectionally and over time., Results: Detailed quality assessment was available for 37 018 patients. Nuchal translucency measurement was successful in 96.3% of women. Local reviewers rejected 0.8% of images, and the single central physician reviewer rejected a further 2.9%. Multivariate analysis indicated that higher body mass index, earlier gestational age and transvaginal probe use were predictors of failure of nuchal translucency measurement and central image rejection (P = 0.001). Epidemiological monitoring identified a drift in measurements over time., Conclusion: Despite initial training and continuous image review, changes in nuchal translucency measurements occur over time. To maintain screening accuracy, ongoing quality assessment is needed.

First trimester combined screening can be performed using maternal serum pregnancy-associated plasma protein A, total human chorionic gonadotropin (hCG) and ultrasound measurement of nuchal translucency at 11-13 weeks of pregnancy. Our objective was to explore the effects of covariates on total hCG in the first trimester. First trimester total hCG levels were significantly increased in twins (median = 1.87 MoM), mildly increased in pregnancies achieved by in vitro fertilization (1.04 MoM) and decreased in smokers (0.80 MoM).

Objective: The objective of the study was to further explore relationships between human chorionic gonadotropin (hCG), TSH, and free T4 in pregnant women at 11 through 18 wk gestation., Study Design: The design of the study was to analyze hCG in comparison with TSH and free T4, in paired first- and second-trimester sera from 9562 women in the First and Second Trimester Evaluation of Risk for Fetal Aneuploidy trial study., Results: hCG is strongly correlated with body mass index, smoking, and gravidity. Correlations with selected maternal covariates also exist for TSH and free T4. As hCG deciles increase, body mass index and percent of women who smoke both decrease, whereas the percent of primigravid women increases (P < 0.0001). hCG/TSH correlations are weak in both trimesters (r2 = 0.03 and r2 = 0.02). TSH concentrations at the 25th and fifth centiles become sharply lower at higher hCG levels, whereas 50th centile and above TSH concentrations are only slightly lower. hCG/free T4 correlations are weak in both trimesters (r2 = 0.06 and r2 = 0.003). At 11-13 wk gestation, free T4 concentrations rise uniformly at all centiles, as hCG increases (test for trend, P < 0.0001), but not at 15-18 wk gestation. Multivariate analyses with TSH and free T4 as dependent variables and selected maternal covariates and hCG as independent variables do not alter these observations., Conclusions: In early pregnancy, a woman's centile TSH level appears to determine susceptibility to the TSH being suppressed at any given hCG level, suggesting that hCG itself may be the primary analyte responsible for stimulating the thyroid gland. hCG affects lower centile TSH values disproportionately.

Objective: The purpose of this study was to examine how closely hypothyroidism management in the general pregnancy population satisfies recently issued guidelines and to determine whether improvements are indicated., Study Design: This was an observational study in which women at 5 recruitment centers in the first- and second-trimester evaluation of risk for aneuploidy trial allowed the use of sequentially obtained first- and second-trimester sera for additional research. Three hundred eighty-nine women had hypothyroidism by self-report. Thyroid-related measurements were performed on all samples between July 2004 and May 2005., Results: Forty-three percent of the thyroid-stimulating hormone (TSH) values are at or above recently recommended guidelines in the first trimester (2.5 mU/L), as opposed to 33% of the values in the second trimester (3.0 mU/L). Twenty percent of the TSH values are at or above a less restrictive 98th percentile of normal in the first trimester, as opposed to 23% of the values in the second trimester. Mean TSH levels are higher in women with antibodies. Free thyroxine values are unremarkable., Conclusion: Future strategies should focus on more effectively treating women with hypothyroidism who have persistently elevated TSH values.

Objective: The purpose of this study was to calculate first and second trimester reference ranges and within-woman correlations for TSH, free T4, and thyroid antibodies., Study Design: TSH, free T4, and thyroid antibodies were measured in paired sera from 9562 women in the FaSTER trial of Down syndrome screening., Results: The median first trimester TSH (1.05 mIU/L) is lower than the second (1.23 mIU/L); and 98th centile is higher (4.15 vs 3.77 mIU/L). Within-woman paired TSH correlations are moderately strong (r(2) = 0.64). Among women with first trimester TSH values above the 98th centile, second trimester values are over the 95th centile in 68%. Median first trimester free T4 values (1.10 ng/dL) are higher than second (1.01 ng/dL). Paired free T4 measurements correlate weakly (r(2) = 0.23). Among women with first trimester free T4 values below the 2nd centile, second trimester values are below the 5th centile in 32%. Antibody measurements correlate strongly between trimesters (thyroperoxidase r(2) = 0.79, thyroglobulin r(2) = 0.83)., Conclusion: TSH and free T4 measurements require gestation-specific reference ranges.

Background: Second-trimester measurement of maternal serum inhibin A is widely used for Down syndrome screening. To date, only a manual enzyme-linked immunosorbent assay (ELISA) produced by Diagnostic Systems Laboratories, Inc (DSL) has been available. The objective of this study was to compare the DSL assay with a new automated assay produced by Beckman Coulter, Inc (Access)., Methods: Residual serum samples from 570 women, who were receiving routine screening for Down syndrome, were retrieved from storage. The Access assay sensitivity, linearity and reproducibility were determined and a method comparison was performed. Inhibin A levels were measured using both assays. Twenty samples from women with confirmed Down syndrome pregnancy were also tested., Results: The Access assay had coefficients of variation of less than 10% across the range of values tested, and a sensitivity below 1 pg/mL. The DSL and Access inhibin A assay values were highly correlated (r = 0.961, r(2) = 0.923), with no apparent outliers. Inhibin A values from the Access assay were a constant 23% lower (95% CI 1-41%) than corresponding values from the DSL assay. Median values from 15 to 20 completed weeks' gestation were computed and found to be consistent with expectations. The weight-adjusted multiples of the median (MoM) levels in the unaffected pregnancies fit a log Gaussian distribution well between at least the 5th and 95th percentiles with corresponding log standard deviations of 0.1960 and 0.1919 for DSL and Access, respectively., Conclusions: With median inhibin A levels appropriately calculated for the Access assay, Down syndrome screening performance is expected to be comparable to that obtained with the manual DSL assay., (2008 John Wiley & Sons, Ltd)

Purpose: To assess nuchal translucency measurements that were performed as part of routine prenatal screening for Down syndrome., Methods: Collect ultrasound measurements of nuchal translucency and crown rump length provided by individual sonographers over a 6-month period to six North American prenatal screening laboratories, along with the laboratory's nuchal translucency interpretation in multiples of the median. For sonographers with 50 or more observations, compute three nuchal translucency quality measures (medians, standard deviations, and slopes), based on epidemiological monitoring., Results: Altogether, 23,462 nuchal translucency measurements were submitted by 850 sonographers. Among the 140 sonographers (16%) who submitted more than 50 observations, 76 (54%) were found to have all three quality measures in the target range. These 140 sonographers collectively accounted for 14,210 nuchal translucency measurements (61%). The most common single measure to be out of range was nuchal translucency multiples of the median, found for 29 of the 140 sonographers (21%)., Conclusion: Laboratories should routinely monitor the quality of nuchal translucency measurements that are received for incorporation into Down syndrome screening risk calculations and interpretations. When possible, instituting sonographer-specific medians and providing individualized feedback about performance and numbers of women tested offer the potential to yield more consistent and improved performance.

Down syndrome (DS) is the most prevalent chromosomal disorder, accounting for significant morbidity and mortality. Definitive diagnosis requires invasive amniocentesis, and current maternal serum-based testing requires a false-positive rate of about 5% to detect 85% of affected pregnancies. We have performed a comprehensive proteomic analysis to identify potential serum biomarkers to detect DS. First- and second-trimester maternal serum samples of DS and gestational age-matched controls were analyzed using multiple, complementary proteomic approaches, including fluorescence 2-dimensional gel electrophoresis (2D-DIGE), 2-dimensional liquid chromatography-chromatofocusing (2D-CF), multidimensional protein identification technology (MudPIT; LC/LC-MS/MS), and MALDI-TOF-MS peptide profiling. In total, 28 and 26 proteins were differentially present in first- and second-trimester samples, respectively. Of these, 19 were specific for the first trimester and 16 for the second trimester, and 10 were differentially present in both trimesters. Analysis of MALDI-TOF-MS peptide profiles with pattern-recognition software also discriminated between DS and controls in both trimesters, with an average recognition capability approaching 96%. A majority of the biomarkers identified are serum glycoproteins that may play a role in cellular differentiation and growth of fetus. Further characterization and quantification of these markers in a larger cohort of subjects may provide the basis for new tests for improved DS screening.

Prenatal screening for Down syndrome in the late first trimester involves the measurement of maternal serum markers and the fetal ultrasound marker, nuchal translucency (NT). In addition to the established first trimester maternal serum markers, pregnancy-associated plasma protein-A (PAPP-A), and the free beta-subunit of hCG (free beta), studies have indicated that the known second trimester markers, total hCG and inhibin-A (DIA), are also useful in screening in the late first trimester. In this chapter, we review the existing literature on first trimester biochemical and ultrasound markers for Down syndrome, develop week-specific marker parameters, and combine the results via modeling in a comprehensive overview of screening performance. All first trimester markers vary in their usefulness during the 11 through 13 completed week-screening window and the literature is reasonably consistent. NT is the best single marker for Down syndrome in the first trimester of pregnancy (weighted summary detection rate is 60% at a constant 5% false positive rate). The two best maternal serum markers, taken individually, are PAPP-A and free beta (weighted summary detection rates of 36% and 37%, respectively). Combining maternal age, NT and PAPP-A, with either free beta, total hCG, or DIA gives similar screening performance (weighted summary detection rates of 83%, 81%, and 81%, respectively). When both free beta and DIA, or total hCG and DIA are combined with maternal age, NT and PAPP-A, weighted summary detection rates are 85% and 83%, respectively.

Objective: To determine whether first- and second-trimester Down syndrome screening markers and screen-positive rates are altered in pregnancies conceived using assisted reproductive technologies (ARTs)., Methods: ART pregnancies in the multicenter FASTER trial were identified. Marker levels were evaluated for five types of ART: in vitro fertilization with ovulation induction (IVF-OI), IVF with OI and egg donation (IVF-OI-ED), IVF with ED (IVF-ED), and intrauterine insemination with OI (IUI-OI) or without OI (IUI). Each group was compared to non-ART controls using Mann-Whitney U analysis., Results: First-trimester marker levels were not significantly different between ART and control pregnancies, with the exception of reduced PAPP-A levels in the IUI-OI group. In contrast, second-trimester inhibin A levels were increased in all ART pregnancies, estriol was reduced and human chorionic gonadotropin (hCG) was increased in IVF and IUI pregnancies without ED, and alpha-fetoprotein (AFP) was increased in ED pregnancies. Second-trimester screen-positive rates were significantly higher than expected for ART pregnancies, except when ED was used., Conclusions: These data show that ART significantly impacts second-, but not first-, trimester markers and screen-positive rates. The type of adjustment needed in second-trimester screening depends on the particular type of ART used.

Objectives: To retrospectively evaluate whether increased serum levels of total activin A (t-activin A) are found in women who subsequently experience preterm delivery (PTD)., Methods: Data on maternal serum t-activin A concentrations were available from a total of 84 singleton pregnant women and included 14 PTD pregnancies, each matched for gestational age and length of freezer storage, with 5 control pregnancies having term delivery (TD). Analyte values were expressed as multiple(s) of the control median., Results: The median t-activin A for controls and cases was 1.00 +/- 0.45 and 1.27 +/- 0.53 MoM, respectively. Univariate analysis of the MoM values was performed using the Kaplan-Meier algorithm. Differences in the rate of delivery using a t-activin A MoM cut-off of > or = 1 SD (equivalent to 1.26 MoM) were analysed using the log rank test. The cumulative rate of PTD (< 37 weeks) was significantly higher for women with t-activin A concentrations > or = 1.26 MoM than those with t-activin A concentrations below this cut-off (40% vs.. 10%, p-value = 0.0218 log rank test)., Conclusions: T-activin A concentration is higher in women who will develop PTD in a low-risk population. T-activin A values are inversely proportional to the time elapsed from blood test to delivery. Prospective studies would determine the precise discriminability of this marker for PTD and the best week for performing the blood test, allowing for a proper calculation of the detection rate and a positive predictive value., (2006 John Wiley & Sons, Ltd.)

Objective: The purpose of this study was to examine the levels of first- and second-trimester maternal serum markers used in Down syndrome screening in relation to the time between sample collection and arrival at the laboratory., Methods: The FASTER trial, designed to compare first- and second-trimester screening tests for aneuploidy, has recently been completed, having recruited more than 38,000 patients. According to the trial protocol, all blood samples were drawn in serum separator tubes, centrifuged within 30 min and stored at 4 degrees C until shipment by air express. To examine the effect of delayed shipment, serum marker levels (expressed as multiple of the median--MoM) were evaluated in the first- and second-trimester samples and stratified by the number of days between serum collection and laboratory receipt., Results: Under specified collection and shipment conditions, first and second-trimester screening marker mean levels and degrees of variance were stable for up to 9 days, with the exception of unconjugated estriol, which was stable for up to 6 days., Conclusion: The levels of first- and second-trimester Down syndrome screening markers can be measured reliably when the sample is centrifuged, refrigerated until shipment and received in the laboratory within a week of being drawn. A conservative approach would be to restrict testing to within 6 days of draw, with the intent to keep shipping delays to a minimum., (2006 John Wiley & Sons, Ltd.)

Background: Increased second-trimester levels of maternal serum HCG in IVF conceptions lead to an increased false-positive rate in Down syndrome screening. Increased levels of cell-free fetal DNA (cffDNA) in maternal plasma have been correlated with increased HCG levels. Our aim was to determine whether cffDNA levels are elevated in IVF pregnancies compared with natural pregnancies., Methods: Sixteen archived second-trimester serum samples from IVF pregnancies were matched with five control samples from naturally conceived pregnancies per case, all carrying a singleton male fetus. cffDNA concentrations were measured by real-time PCR amplification of a Y chromosome sequence and compared with four standard second trimester serum screening markers (alpha-fetoprotein, estriol, HCG and inhibin A)., Results: Mean cffDNA levels for cases and controls were 57.9 and 57.1 genome equivalents/ml, respectively (P = 0.95). Mean observed rank (from 1 to 6) of cffDNA was 3.625 in the IVF conceived group, compared with an expected value of 3.5 (P = 0.53). No significant correlations were observed between cffDNA and serum markers., Conclusions: IVF does not affect levels of cffDNA, which appears to be independent of traditional screening markers (e.g. HCG). Therefore, cffDNA can be used as an additional serum marker (e.g. Down syndrome screening) without adjustment for IVF pregnancies.

Prenatal screening for Down syndrome in the early second trimester with multiple maternal serum markers has been available for more than 15 years. The multiple marker combination with the highest screening performance currently available is alpha-fetoprotein (AFP), unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and inhibin A, together with maternal age (so-called quad marker test). With this combination, a detection rate of 80% at a 5% false positive rate is achieved. Inhibin A, the newest addition to second trimester serum screening, is an alpha-beta subunit hormone of placental origin, and is measured using a monoclonal two-site ELISA validated for use in prenatal screening. Quality control parameters for inhibin A measurement are acceptable and are monitored through the proficiency testing program administered by the College of American Pathologists. Research into other possible second trimester screening markers has included studies on the maternal urine and serum levels of an hCG variant, hyperglosylated hCG (h-hCG; invasive trophoblast antigen). Recent data indicate that h-hCG is similar to hCG itself, although its measurement in maternal urine may improve the performance of the established serum marker combinations. With the introduction of first trimester screening markers and their use in an integrated first and second trimester marker approach to screening, and with the fact that many women do not seek prenatal care until the early second trimester, prenatal screening for Down syndrome using second trimester serum markers remains a major resource in obstetrical care.

We present second-trimester serum marker levels in cases of twin pregnancy with complete hydatidiform mole and a coexistent fetus (CHMCF). Second-trimester inhibin A (InhA) levels have not been previously reported in such cases. Second-trimester maternal serum screening, alpha-fetoprotein (AFP), unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and InhA measurements combined with maternal age to estimate a patient's risk of Down syndrome during pregnancy was performed as a routine prenatal test in 2 cases of CHMCF. Hospital records containing serum marker data, patient history, pathology reports, and pregnancy outcome were reviewed. In cases of CHMCF, maternal serum AFP and uE3 levels were similar to those of a normal singleton pregnancy, whereas hCG and InhA levels were markedly increased. Second-trimester maternal serum marker profiles in cases of CHMCF are a composite of normal singleton and molar tissue secretions. We have found, for the first time, that second-trimester InhA levels are markedly increased in these cases. Serum marker levels may be useful in diagnosis of CHMCF, prenatal counseling, and evaluation of risk for persistent trophoblastic disease.

Objectives: To determine the levels of placenta growth factor (PlGF) in second-trimester maternal serum samples from pregnancies affected with fetal Down syndrome and from those that developed preeclampsia and to assess the utility of PlGF as a screening tool for these conditions., Methods: Residual second-trimester maternal serum samples were retrieved from freezer storage for 39 cases of Down syndrome and 44 pregnancies that later developed preeclampsia. Each case was matched to 5 control samples for gestational age at collection and duration of freezer storage. PlGF levels were measured in each sample by enzyme-linked immunosorbent assay (ELISA)., Results: PlGF levels increased with gestational age between 15 and 20 gestational weeks. After adjusting for gestational-age effects, the median level of PlGF was 1.01 MoM in Down syndrome pregnancy and 0.74 MoM in pregnancies that developed preeclampsia, which were not significantly different from matched controls. The duration between sampling and onset of preeclampsia did not have an effect on the PlGF level., Conclusion: PlGF levels are not significantly altered in second-trimester maternal serum samples from cases of Down syndrome or in pregnancies that develop preeclampsia.

To date, the only routine clinical application of inhibin or activin measurement in testing for fetal abnormalities has been the use of inhibin A in prenatal screening for trisomy 21 (Down syndrome). Second trimester maternal serum levels of inhibin A are, on average, two-fold higher in Down syndrome than in unaffected pregnancies. Although the biology of altered second trimester maternal serum analyte levels in Down syndrome pregnancy cannot yet be explained, it seems that fetal products tend to be decreased, while placental products tend to be increased. This pattern holds true for inhibin A because maternal serum levels appear to be derived from placental rather than fetal sources. Therefore, the measurement of inhibins and activins in maternal fluids, although clinically useful and relatively easy to obtain, may not be helpful in studying their role in human fetal development. Studies in transgenic mice indicate a role for activin, follistatin, and activin receptor type IIA in development of the palate and craniofacial region. Cleft palate is a common birth defect and is associated with serious feeding and respiratory complications in newborns. We have begun to investigate the potential role of activin in human craniofacial development by examining the spatial and temporal expression of inhibin/activin subunits, follistatin and the activin receptors in the fetal palate. Palate tissues were collected at autopsy from fetuses ranging in gestational age from 9 to 42 weeks, and 8 week embryonic tissues were also examined. Tissues were either stored in paraffin for immunocytochemistry or were frozen for RT-PCR examination of the expression of inhibin/activin proteins or mRNAs, respectively. To date, betaA subunit, follistatin, and activin receptor, but not alpha and betaB subunit, mRNAs are present in palate tissues and inhibin/activin betaA immunoreactivity has been consistently observed in developing bone. Expression of the activin A subunit and its receptors in the human fetal palate are consistent with a developmental role. Studies are ongoing to determine whether altered activin biosynthesis is associated with cleft palate. Future studies of fetal tissues may help to elucidate other roles for the TGF-beta family in human development.

Inhibin A is secreted in significant quantities by the corpus luteum and fetoplacental unit, suggesting a role in fertility and pregnancy. Negative feedback regulation of follicle-stimulating hormone during pregnancy is one expected function of inhibin A, but the complete repertoire of actions of this hormone in pregnancy, including paracrine and autocrine actions, is yet to be fully understood. Inhibin A levels have been carefully described throughout normal pregnancy and studied in association with maternal and fetal complication such as intrauterine growth restriction, preterm labor or delivery, and preeclampsia. The first clinical application of inhibin A measurement in pregnancy has been its use as a second-trimester maternal serum marker for Down syndrome. Our laboratory was among the first, in 1998, to implement Quad marker screening, inhibin A measurement in conjunction with alpha-fetoprotein, unconjugated estriol, and human chorionic gonadotropin, to assess patients' risk of having a Down syndrome baby. The test performance of the Quad test has been validated by several large studies, detecting about 80% of Down syndrome pregnancies at a 5% false-positive rate. The present review describes Down syndrome and the use of inhibin A in second-trimester prenatal screening. We also address the method used for inhibin A measurement, the biology of inhibin A in Down syndrome pregnancy, and the effects of covariates and other fetal abnormalities on inhibin A levels.