P-353 Placenta previa in In Vitro Fertilization and unassisted pregnancies – is there a difference in perinatal outcomes and placental histology?

Abstract

Abstract Study question Why is In-vitro-fertilization (IVF) an independent risk factor for placenta previa (PP). Summary answer While PP in non-assisted pregnancies is probably associated with previous cesarean deliveries (CD), in IVF it is more “sporadic”, and may complicate any index pregnancy. What is known already PP is more prevalent following IVF pregnancies as compared with unassisted pregnancies, with an increased risk of three to six-fold according to some authors. The etiology for this increased risk in IVF pregnancies in unclear, and may be related to reproductive procedures performed or to subfertility characteristics which have led to IVF. Study design, size, duration A retrospective-cohort study of deliveries with PP between 2008 and 2021. A total of 182 pregnancies were included. Participants/materials, setting, methods Placental histopathology, obstetric and neonatal outcomes were compared between IVF and unassisted pregnancies. Included, were singleton deliveries complicated by PP at gestational weeks (GA)> 24. Placental pathology was obtained utilizing the well-accepted Amsterdam criteria. Main results and the role of chance Out of 182 pregnancies which were included - 23 IVF pregnancies (IVF group) and 159 in the unassisted pregnancies (Control group). The control group was characterized by higher gravidity (p = 0.007) and parity (p < 0.001), whereas the IVF group- by a higher rate of nulliparity (p < 0.001) and diabetes mellitus (p = 0.04). A higher rate of patients with past CDs was noted in unassisted pregnancies, although not statistically significance (38.9% versus 21.7%, p = 0.10). There was a trend for a lower placental weight in the control group, and a higher incidence of placental weight below the 10thpercentile in this group (47.8% versus 13.9%, p = 0.001). No differences were noted in maternal and fetal vascular lesions. Nevertheless, IVF and unassisted pregnancies entail similar perinatal outcomes in cases of PP. Limitations, reasons for caution A major limitation was our small sample size in the IVF group. Despite a power calculation, larger study groups would have possibly allowed for the demonstration of additional differences in outcomes, including previous cesarean deliveries and placenta accreta. Moreover, this limitation prevented us from matching against possible cofounders. Wider implications of the findings While a growing proportion of pregnancies worldwide are conceived by IVF, possible iatrogenic side effects should be studied. As PP is of clinical importance, it is essential to diagnose it on time, as well as study the mechanisms and risk factors behind it, which could possibly help with its prevention. Trial registration number 0282-20-WOMC