The research team conducted the study to determine whether assisted reproductive technology (ART) singleton pregnancies are associated with an increased risk of placental anomalies compared with non?ART singleton pregnancies

Among singleton pregnancies, assisted reproductive technology (ART) is associated with an increased risk of placental anomalies, according to a review published online May 8 in BJOG: An International Journal of Obstetrics & Gynaecology

Belinda G. Vermey, from the University of New South Wales in Sydney, and colleagues conducted a systematic literature review and meta-analysis of studies evaluating whether ART singleton pregnancies are associated with an increased risk of placental anomalies versus non-ART singleton pregnancies.

Assisted reproduction technologies (ART) are increasingly being used to treat infertility worldwide. It is estimated that >1.8 million ART cycles were undertaken globally in 2010 and that more than 6.5 million children have been conceived over the past three decades. Since ART involves the application of novel technologies in the creation of embryos, there has always been a strong interest in assessing and quantifying the potential risks with which it is associated.

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).

Based on 33 low- to moderate-quality studies (124,215 ART and 6,054,729 non-ART singleton pregnancies), the risk of placenta previa, placental abruption, and morbidly adherent placenta was higher in ART versus spontaneously conceived pregnancies (odds ratios [ORs], 3.76, 1.87, and 2.27, respectively).

Similarly, the risk of placenta previa and placental abruption was higher in ART than in non-ART (subfertile patients; OR, 2.51 and 1.61, respectively). Among frozen-embryo transfer ART pregnancies, the risk of placenta previa was higher, but not significantly, versus spontaneously conceived pregnancies (OR, 2.42; 95 percent confidence interval, 0.63 to 9.3).

Outcomes

As we anticipated some of the published studies to have produced adjusted odds ratios (aOR) through multivariable analyses, the outcome measure was chosen for the current systematic review and meta?analysis was the odds ratio (OR) for each type of abnormal placentation in ART and non?ART pregnancies.

"Singleton ART pregnancies are associated with an increased risk of placental anomalies compared with non-ART singleton pregnancies," the authors write.