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Objectives: To determine the risk of a Down syndrome (DS) live birth for women 45 years of age and over., Methods: A meta-analysis of data from five published articles, 13 EUROCAT congenital anomaly population registers and two unpublished sources., Results: Information was available on the number of DS live births occurring amongst 13,745 live births to women 45 years of age and over. Information was also available on DS pregnancies diagnosed prenatally that were subsequently terminated. These pregnancies were adjusted for expected fetal loss to estimate the number of live births that would have occurred in the absence of prenatal diagnoses, when a total of 471 DS live births were estimated to have occurred. The risk of a DS birth did not increase for women 45 years of age and over. The average risk was 34 per 1000 births (95% CI: 31-37)., Conclusion: The risk of a DS live birth for women 45 years of age and over is considerably lower than has often been previously assumed. The most likely explanation is that women of this age are more likely to miscarry DS pregnancies than younger mothers.

Objectives: To display and compare the different published formulae that specify the association between maternal age and the risk of a Down syndrome live birth., Methods: Papers published since 1987 on the prevalence of Down syndrome live births in relation to maternal age were located using MEDLINE and the references given in other papers. The data series and the models fitted to them were plotted to obtain a visual idea of their similarities and differences., Results: The observed and modelled age-specific rates for Down syndrome births were remarkably similar in all published series of data for women up to the age of 35, were reasonably similar for women aged 35 to 45, but differed for women older than 45., Conclusion: In practice, the overall small differences in age-related risk between the different studies did not materially affect the performance of antenatal screening for Down syndrome. If a choice is to be made, the analysis based on the National Down Syndrome Cytogenetic Register (NDSCR) has marginal advantages since it is based on the largest data set and the corresponding model fits the data well. More data is needed to clarify the pattern of risk with maternal age among women over 45 years of age., (Copyright 2003 John Wiley & Sons, Ltd.)

Objective To illustrate regional changes that occurred in screening for Down's syndrome (trisomy 21) in England and Wales from 1989 to 2008. Methods The National Down Syndrome Cytogenetic Register has collected data on all ante- and postnatal diagnoses of Down's syndrome in England and Wales since 1989 (n = 27,954). The percentages of (i) diagnoses made antenatally, (ii) antenatal diagnoses that had nuchal translucency (NT) measured, and (iii) antenatal diagnoses in mothers aged 37 and over with advanced maternal age as the sole recorded indication for diagnosis are presented according to where the mother lived Government Office Region), year of diagnosis (1989-1994, 1995-2000, 2001-2006, 2007-2008), and maternal age (<37 years, ≥37 years). Results The percentage of cases diagnosed antenatally has increased in younger women but varies between regions. It remained relatively constant at approximately 70% in older women. The use of NT measurement in antenatal screening has expanded rapidly but varies regionally, being most common in London and the South East where, in 2007-2008, over 75% of antenatal diagnoses in older women had NT measured. The sole indication of advanced maternal age has substantially reduced, and was less than 10% in older mothers in all regions in 2007-2008. Conclusions There are regional and maternal age variations in Down's syndrome screening and diagnosis. Some regions used NT measurements, and eliminated advanced maternal age as sole reason for antenatal diagnostic testing more quickly than others. The reasons for variations need to be identified and addressed to ensure that when new screening techniques become available, regional differences are minimized. [ABSTRACT FROM AUTHOR]

Objectives To determine the excess risk of non-chromosomal congenital anomaly (NCA) among teenage mothers and older mothers. Design and setting Population-based prevalence study using data from EUROCAT congenital anomaly registers in 23 regions of Europe in 15 countries, covering a total of 1.75 million births from 2000 to 2004. Participants A total of 38 958 cases of NCA that were live births, fetal deaths with gestational age ≥20 weeks or terminations of pregnancy following prenatal diagnosis of a congenital anomaly. Main outcome measures Prevalence of NCA according to maternal age, and relative risk (RR) of NCA and 84 standard NCA subgroups compared with mothers aged 25–29. Results The crude prevalence of all NCA was 26.5 per 1000 births in teenage mothers (<20 years), 23.8 for mothers 20–24 years, 22.5 for mothers 25–29 years, 21.5 for mothers 30–34 years, 21.4 for mothers 35–39 years and 22.6 for mothers 40–44 years. The RR adjusted for country for teenage mothers was 1.11 (95% CI 1.06–1.17); 0.99 (95% CI 0.96–1.02) for mothers 35–39; and 1.01 (95% CI 0.95–1.07) for mothers 40–44. The pattern of maternal age-related risk varied significantly between countries: France, Ireland and Portugal had higher RR for teenage mothers, Germany and Poland had higher RR for older mothers. The maternal age-specific RR varied for different NCAs. Teenage mothers were at a significantly greater risk ( P < 0.01) of gastroschisis, maternal infection syndromes, tricuspid atresia, anencephalus, nervous system and digestive system anomalies while older mothers were at a significantly greater risk ( P < 0.01) of fetal alcohol syndrome, encephalocele, oesophageal atresia and thanatophoric dwarfism. Conclusions Clinical and public health interventions are needed to reduce environmental risk factors for NCA, giving special attention to young mothers among whom some risk factors are more prevalent. Reassurance can be given to older mothers that their age in itself does not confer extra risk for NCA. [ABSTRACT FROM AUTHOR]

Objectives: To revise the estimates of maternal age specific live birth prevalence of Down's syndrome in the absence of antenatal screening and selective termination using newly available data. Setting and Design: Data were used from the National Down Syndrome Cytogenetic Register (NDSCR), which contains information on nearly all antenatally or postnatally diagnosed cases of Down's syndrome in which a karyotype was confirmed between 1989 and 1998 in England and Wales. It is the largest single series of data on the prevalence of Down's syndrome. Results and conclusion: The prevalence does not continue increasing at an increasing rate with age above age 45 as has been previously assumed. Above this age the rate of increase declines with increasing age. The overall age pattern is sigmoidal. A new logit logistic model is proposed which fits the data well. The risk of a Down's syndrome live birth is given by: risk=1/(1+exp(7.330-4.211/(1+exp(-0.282x(age-37.23))))). [ABSTRACT FROM AUTHOR]

Objectives: The proportion of Down's syndrome pregnancies detected prenatally in England and Wales is lower in younger mothers than in older mothers. This paper examines the reasons for this apparent age inequality. Methods: We used data from the National Down Syndrome Cytogenetic Register (NDSCR) to examine the time trend of the proportion of Down's syndrome pregnancies diagnosed prenatally according to maternal age over the years 1989–2004 in England and Wales. Results: A lower proportion of younger mothers had their Down's syndrome pregnancy detected prenatally than older mothers; however, this gap has been closing over time. For example, for mothers under 25 years of age only 13% of Down's syndrome pregnancies were detected prenatally from 1989 to 1992, with this figure rising to 34% in 2001–2004, compared with proportions of 74% in both periods for mothers over 44 years of age. A lower uptake of screening among younger women could not explain these differences. The differences in detection rates of the screening methods according to maternal age, particularly of the older screening tests, could account for these differences. Conclusions: The closing gap between the proportions of younger and older women having their affected pregnancy prenatally diagnosed is a confirmation of the improvement of screening methods over time. [ABSTRACT FROM AUTHOR]