Placental-related disorders of pregnancy and IVF: does placental histological examination explain the excess risk?

Research question: What are the clinical characteristics of pregnancies complicated by fetal growth restriction (FGR) and preeclampsia in patients who have undergone IVF, and what is the correlation between these complications and histopathological placental findings in such pregnancies. Design: A retrospective cohort of patients who had delivered their babies at our institution who had been diagnosed with preeclampsia, whose babies had been diagnosed with FGR, or both. Deliveries in which the placenta was sent for histopathological examination were included. Computerized files and pathological reports were reviewed, and maternal, obstetric, neonatal outcomes and placental histopathological reports were compared between pregnancies conceived by IVF and controls. Placental lesions were classified according to the Amsterdam criteria. Results: Between December 2008 and December 2018, the placentas of 1114 singleton babies who had received a diagnosis of FGR, whose mothers had received a diagnosis of preeclampisa, or both, were examined. A total of 105 patients conceived with IVF and 1009 were conceived spontaneously. The IVF group was older, of lower parity and had a higher rate of diabetes and chronic hypertension. Deliveries occurred at an earlier gestational age, although birth weight was not significantly different between the groups. The rate of neonatal adverse composite outcome among IVF deliveries was significantly lower (59.0% versus 76.7%; P < 0.001). On placental examination, placental weight, maternal and fetal vascular malperfusion lesions were similar between the groups, whereas villitis of unknown etiology was significantly more common among the IVF group (16.2% versus 8.3%; P = 0.007). Conclusion: Neonatal outcome is relatively favourable in IVF patients with placental-related diseases. Placental chronic villitis is more common in IVF patients, pointing to an additive immunological cause.