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Results from studies evaluating potential effects of prenatal exposure to radio-frequency electromagnetic fields from cell phones on birth outcomes have been inconsistent. Using data on 55,507 pregnant women and their children from Denmark (1996–2002), the Netherlands (2003–2004), Spain (2003–2008), and South Korea (2006–2011), we explored whether maternal cell-phone use was associated with pregnancy duration and fetal growth. On the basis of self-reported number of cell-phone calls per day, exposure was grouped as none, low (referent), intermediate, or high. We examined pregnancy duration (gestational age at birth, preterm/postterm birth), fetal growth (birth weight ratio, small/large size for gestational age), and birth weight variables (birth weight, low/high birth weight) and meta-analyzed cohort-specific estimates. The intermediate exposure group had a higher risk of giving birth at a lower gestational age (hazard ratio = 1.04, 95% confidence interval: 1.01, 1.07), and exposure-response relationships were found for shorter pregnancy duration (P < 0.001) and preterm birth (P = 0.003). We observed no association with fetal growth or birth weight. Maternal cell-phone use during pregnancy may be associated with shorter pregnancy duration and increased risk of preterm birth, but these results should be interpreted with caution, since they may reflect stress during pregnancy or other residual confounding rather than a direct effect of cell-phone exposure. [ABSTRACT FROM AUTHOR]

Aims: To describe specific recommendations of activity restriction, place of care, expected beneficial and adverse effects, and recommended antithrombotic prophylaxis in nine clinical scenarios. Methods: A national survey. All members of the Danish Society of Obstetrics and Gynaecology and the Danish Association of Midwives were asked to complete a tested, structured questionnaire. Results: We sent 1815 invitations; the overall response rate was 54%. A majority of clinicians recommended some form of activity restriction in the nine scenarios. The midwives recommended strict or moderate activity restriction more often than obstetricians in five of the nine scenarios, in women with preterm premature rupture of membranes, preterm labour, cervical ripening, total placenta praevia, and intrauterine growth restriction, whereas no differences were found in the remaining scenarios. Compared to the obstetricians, the midwives also reported that they expected the recommendation to be more effective. Most midwives and obstetricians reported that they thought strict activity restriction was associated with severe or moderate adverse effect, and recommended antithrombotic prophylaxis. Conclusions: Danish obstetricians and midwives prescribe activity restriction in most high-risk pregnancies. The degree of activity restriction and the presumed effect vary between clinicians. This may reflect different attitudes and lack of guidelines based on clinical studies of a possible benefit of activity restriction. [ABSTRACT FROM AUTHOR]

Introduction: In this review a selection of studies published during the period 2002-2010, based on data from the Danish National Birth Cohort linked with other health registers, is described. Illustrative examples of studies addressing perinatal health outcomes (pregnancy complications and fetal and infant health) of a variety of exposures during pregnancy, as well as examples showing different methodological approaches in design and analyses of the studies, are presented. Research topics: The exposures of interest include alcohol drinking, coffee intake, smoking, use of nicotine substitutes, physical exercise, working conditions, medication and infections during pregnancy, and environmental possible toxins. The study designs cover straightforward cohort analyses, case-control studies and sub-cohort analyses with enriched data collection. Conclusion: So far, the Danish National Birth Cohort has provided important knowledge for evidence-based antenatal care by giving more accurate risk estimates for adverse pregnancy outcomes associated with the exposures of interest. Some new potential hazardous exposures during pregnancy have been identified and others have been put to rest. We believe that this investment in epidemiologic infrastructure was well spent. The existence of the Danish National Birth Cohort together with other cohorts and national registers has given Denmark a leading position in reproductive epidemiology. [ABSTRACT FROM PUBLISHER]

Objective: To study whether women conceiving after preimplantation genetic diagnosis (PGD) and their children have greater risks of adverse pregnancy and birth outcomes compared with children conceived spontaneously or after IVF with or without intracytoplasmic sperm injection (ICSI).Design: Historical cohort study.Setting: Not applicable.Patient(s): All deliveries following PGD treatment for single gene and sex-linked disorders or structural chromosomal aberrations (n = 126 deliveries/149 children), IVF/ICSI treatment (n = 30,418 deliveries/36,115 children), and spontaneous conception (n = 896,448 deliveries/909,624 children).Intervention(s): None.Main Outcome Measure(s): Adverse obstetric and neonatal outcomes, such as pre-eclampsia, preterm primary rupture of membranes, placenta previa, abruption of placenta, preterm birth, low birth weight, malformations, and neonatal admission.Result(s): Compared with spontaneously conceived pregnancies, PGD pregnancies were at significantly increased risk of placenta previa (adjusted odds ratio [ORa] 9.1; 95% confidence interval [95% CI] 3.4, 24.9), cesarean section (ORa 2.0; 95% CI 1.3, 2.9), preterm birth (ORa 1.6; 95% CI 1.0, 2.7), shorter gestation (mean difference -3.4 days; 95% CI -5.7, -1.1 days), and longer neonatal admission (mean difference 21 days; 95% CI 15, 28 days). The risks were comparable to that of pregnancies following IVF/ICSI. In subanalyses, adverse outcomes were only present in children conceived by PGD owing to parental monogenetic disorder and comparable to those of children born to parents with monogenic disorders conceiving without PGD, except for a higher risk of placenta previa.Conclusion(s): In this cohort study, the risk of adverse obstetric and neonatal outcomes was mainly related to the underlying parental condition rather than the PGD procedure. [ABSTRACT FROM AUTHOR]