Assisted reproductive technology and risk of adverse obstetric outcomes in dichorionic twin pregnancies: a systematic review and meta-analysis

Objective: To examine whether dichorionic twin pregnancies after assisted reproductive technology (ART) were at higher risk of adverse obstetric outcomes compared with those conceived naturally. Design: Meta-analysis. Setting: University-affiliated teaching hospital. Patient(s): Dichorionic twin pregnancies conceived with ART and naturally. Intervention(s): Studies comparing obstetric outcomes in dichorionic twin pregnancies conceived by ART and naturally were identified by searching PubMed, Google Scholar, Cochrane Libraries, and Chinese databases through July 2015 with no restrictions. Either a fixed-effects 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): Maternal complications and adverse pregnancy outcomes. Result(s): Fifteen cohort studies involving 6,420 dichorionic twins after ART and 13,650 dichorionic twins conceived naturally were included. Most of maternal complications were similar in both groups, but placenta previa (relative risk [RR] = 2.99, 95% confidence interval [CI] 1.51-5.92; I-2 = 0) was significantly more common in the ART group. For neonatal outcomes, the ART group experienced higher risk of preterm birth (RR = 1.13, 95% CI 1.00-1.29; I-2 = 75%), very preterm birth (RR = 1.39, 95% CI 1.07-1.82; I-2 = 71%), low birth weight (RR = 1.11, 95% CI 1.00-1.23; I-2 = 61%), and congenital malformations (RR = 1.26, 95% CI 1.09-1.46; I-2 = 26%). In addition, the ART group had a higher proportion of elective cesarean sections (RR = 1.79, 95% CI 1.49-2.16; I-2 = 60%), but had a similar proportion for emergency cesarean sections. Relevant heterogeneity moderators have been identified by subgroup analysis. No evidence of publication bias was observed. Conclusion(s): The rates of placenta previa, elective cesarean section, preterm birth, very preterm birth, low birth weight, and congenital malformations were significantly higher in dichorionic twin pregnancies after ART. (C) 2016 by American Society for Reproductive Medicine.)