Outcomes of pregnancies with more than one positive prenatal screening result in the first or second trimester

False-Positive Maternal Serum Screens in the Second Trimester as Markers of Placentally Mediated Complications Later in Pregnancy: A Systematic Review and Meta-Analysis

BACKGROUND

Multiple-marker, maternal serum screening (MSS) has been the cornerstone of prenatal diagnosis since the 1980s. While combinations of these markers are used to predict fetal risk of Down syndrome and other genetic conditions, there is some evidence that individual markers may also predict nongenetic pregnancy complications, particularly those related to placental dysfunction. The objective of this meta-analysis was to investigate the utility of false-positive, second-trimester MSS for Down syndrome as a marker of placentally mediated complications amongst singleton pregnancies globally.

METHODS

Electronic searches of PubMed, Medline, Embase, CINAHL, Web of Science, Scopus, and grey literature to 2019 were performed to identify observational studies comparing risk of pregnancy complications amongst pregnancies with false-positive MSS versus controls. A random-effects model of pooled odds ratios by outcome of interest (stillbirth, preeclampsia, fetal growth restriction, and preterm birth) and subgrouped by type of MSS test (double-, triple-, and quadruple-marker MSS) was used.

RESULTS

16 studies enrolling 68515 pregnancies were included. There were increased odds of preeclampsia (OR 1.28, 95% CI 1.09-1.51) and stillbirth (OR 2.46, 95% CI 1.94-3.12) amongst pregnancies with false-positive MSS. There was no significant association with preterm birth or growth restriction.

CONCLUSIONS

There is some evidence of an association between false-positive, second-trimester MSS for Down syndrome and increased odds of preeclampsia and stillbirth. Future large-scale prospective studies are still needed to best determine the predictive value of false-positive MSS as a marker of placentally mediated complications later in pregnancy and evaluate potential clinical interventions to reduce these risks.

Prevalence of Neural Tube Defects and the Impact of Prenatal Diagnosis in Three Districts of Beijing, China

BACKGROUND

The objectives of this study were to explore the prevalence of neural tube defects (NTDs) in three districts of Beijing, and to evaluate the impact of prenatal diagnosis on the prevalence.

METHODS

Data were collected between 2006 and 2012 from the Beijing Birth Defects Surveillance System. P₁₃ and P₂₈ represent the prevalence of NTDs diagnosed from 13 weeks and 28 weeks of gestation, respectively, to 7 days after delivery. Populations were classified as household (permanent) and non-household (non-permanent) because differences exist in access to health care, education, and income, among others.

RESULTS

The P₁₃ of NTDs was 11.7 per 10 000 births in the three districts, which declined from 2006-12. In addition, the prevalence of NTDs in the non-household population was 1.7-fold higher than that among the household population. The P₁₃ of anencephaly, spina bifida, and encephalocele were 5.3, 4.9, 1.6, respectively, per 10 000 births. The P₂₈ of NTDs only represented 29.1% of P₁₃ , and this proportion decreased over the 7-year period.

CONCLUSIONS

The prevalence of NTDs remains high in the three districts of Beijing, and the rate was higher in the non-household than household population. The prevalence of birth defects would be under estimated by almost 70 per cent if the report time was set on 28 weeks' gestation or later compared with report time on 13 weeks of gestation. It is better to set the report time earlier in birth defect surveillance in contemporary China.