Placental characteristics in women with polycystic ovary syndrome

Abstract

Study question: Are macroscopic and microscopic placental characteristics in a heterogeneous group of women diagnosed with polycystic ovary syndrome (PCOS) different from those of a low-risk general population?

Summary answer: Women with PCOS have significantly different microscopic placental characteristics compared with control women, independently from pregnancy complications.

What is known already: Non-obese women with PCOS who conceived spontaneously have a significantly reduced placental volume and weight, with more chronic villitis and intervillositis compared with healthy controls.

Study design, size, duration: A subset of a large prospective cohort study of pregnant women with PCOS was used. Healthy (low-risk) women who delivered at term after an uncomplicated pregnancy were used as the reference population. The placentas of 73 women with PCOS were analysed and compared with 209 placentas of healthy women.

Participants/materials, setting, methods: Placentas were collected after delivery from women with PCOS who were followed from prior to conception until delivery. The placentas were macroscopically and microscopically analysed and compared with placentas of healthy women with either a spontaneous start of labour who delivered at term or who had an elective Caesarean section.

Main results and the role of chance: After adjusting for potential confounders, placentas from women with PCOS showed more chorioamnionitis (P < 0.001), funisitis (P = 0.019), villitis (P = 0.045), thrombosis (P = 0.018), infarction (P = 0.010), villous immaturity (P = 0.009) and nucleated fetal red blood cells (P < 0.001). In a subgroup analysis, among women with and without pregnancy complications within the PCOS group, only the occurrence of thrombosis was increased in pregnancies complicated by pregnancy-induced hypertension or pre-eclampsia (30%, versus 0% in gestational diabetes pregnancies and 13% in uncomplicated pregnancies; P = 0.008).

Limitations, reasons for caution: There might be a small proportion of women with PCOS in the reference group, since this group was not screened for PCOS. As a result, the observed difference may be an underestimation of the true difference. Placentas were stored for up to 72 h at 4°C, this is common practice but some degenerative changes cannot be ruled out absolutely. Also, there is possibility that baseline differences between the groups may in part explain some of the differences in placental pathology.

Wider implications of the findings: Our findings suggest that, in general, women with PCOS can have placental alterations associated with an increased hypoxic state, which seems not to be caused by the increased incidence of pregnancy complications.

Trial registration: ClinicalTrials.gov NCT00821379.

Keywords: histology; microscopic; placenta; polycystic ovary syndrome; pregnancy complications.