Are singleton pregnancies after assisted reproduction technology (ART) associated with a higher risk of placental anomalies compared with non-ART singleton pregnancies? A systematic review and meta-analysis

Background Placental anomalies (placenta praevia, placental abruption, morbidly adherent placenta and cord insertion anomalies) are associated with maternal and fetal morbidity and mortality. It has been suggested these might be more prevalent in pregnancies after assisted reproduction technology (ART). Objectives To determine whether ART singleton pregnancies are associated with an increased risk of placental anomalies compared with non-ART singleton pregnancies. Search strategy MEDLINE, EMBASE, CENTRAL, Web of Science and Scopus (January 2018). Selection criteria Cohort studies reporting placental anomalies in ART and non-ART singleton pregnancies. Data collection and analysis We report pooled odds ratios (OR) for the comparisons: (1) ART versus SC (spontaneously conceived), (2) ART versus non-ART (unspecified), (3) FET-ART (frozen-embryo transfer) versus SC, (4) ART versus non-ART (subfertile patients). Study quality was assessed using a modified Newcastle -Ottawa scale. Main results 33 low/moderate quality studies evaluated 124 215 ART and 6 054 729 non-ART singleton pregnancies. Risk of placenta praevia, placental abruption and morbidly adherent placenta was higher in ART than SC pregnancies: odds ratio (OR) (OR 3.76, 95% CI 3.09-4.59); (OR 1.87, 95% CI 1.70-2.06) and (OR 2.27, 95% CI 1.79-2.87) respectively. Risk of placenta praevia and placental abruption was higher in ART than in non-ART (subfertile patients): (OR 2.51, 95% CI 2.12-2.98) and (OR 1.61, 95% CI 1.33-1.95) respectively. Results were similar when comparing ART with unspecified non-ART pregnancies. Risk of placenta praevia was higher, but not significantly so, in FET-ART than in SC pregnancies (OR 2.42, 95% CI 0.63-9.30). Conclusions Singleton ART pregnancies are associated with an increased risk of placental anomalies compared with non-ART singleton pregnancies.