Pregnancy-related complications and adverse pregnancy outcomes in multiple pregnancies resulting from assisted reproductive technology: a meta-analysis of cohort studies

Objective To provide an up-to-date comparison of pregnancy-related complications and adverse pregnancy outcomes of multiple pregnancies generated with assisted reproductive technology (ART) vs. spontaneous conception. Design Meta-analysis. Setting University-affiliated teaching hospital. Patient(s) Multiple pregnancies conceived by ART or naturally. Intervention(s) Searches through October 2014 were conducted on PubMed, Google Scholar, Cochrane Libraries, China Biology Medicine disc, Chinese Scientific Journals Fulltext Database, China National Knowledge Infrastructure, and Wanfang Data, to identify studies that met prestated inclusion criteria. Either a fixed- or a random-effects model was used to calculate the overall combined risk estimates. Subgroup analysis was performed to explore potential heterogeneity moderators. Main Outcome Measure(s) Pregnancy-related complications and adverse pregnancy outcomes. Result(s) Thirty-nine cohort studies involving 146,008 multiple births were included in the meta-analysis. Multiple pregnancies from ART were associated with a higher risk of premature rupture of membranes (relative risk [RR] = 1.20, 95% confidence interval [CI]: 1.05–1.37; I 2 = 15%); pregnancy-induced hypertension (RR = 1.11, 95% CI: 1.04–1.19; I 2 = 6%); gestational diabetes mellitus (RR = 1.78, 95% CI: 1.25–2.55; I 2 = 42%); preterm birth (RR = 1.08, 95% CI: 1.03–1.14; I 2 = 83%); very preterm birth (RR = 1.18, 95% CI: 1.04–1.34; I 2 = 79%); low birth weight (RR = 1.04, 95% CI: 1.01–1.07; I 2 = 47%); very low birth weight (RR = 1.13, 95% CI: 1.01–1.25; I 2 = 62%); and congenital malformation (RR = 1.11, 95% CI: 1.02–1.22; I 2 = 30%). The relevant heterogeneity moderators have been identified by subgroup analysis. Sensitivity analysis yielded similar results. No evidence of publication bias was observed. Conclusion(s) Although the role of potential bias and evidence of heterogeneity should be carefully evaluated, the present study suggests that multiple pregnancies generated via ART, vs. spontaneous conception, are associated with higher risks of pregnancy-related complications and adverse pregnancy outcomes. Further research is needed to determine which aspect of ART poses the most risk and how this risk can be minimized.