Is there a relationship between fetal sex and placental pathological characteristics in twin gestations?

<bold>Background: </bold>Placenta plays a central role in mediating growth and development of fetuses. Sex-specific placentas may complicate this role.<bold>Methods: </bold>The study aimed at investigating the association between fetal sex and placental pathological findings in twin gestations using generalized estimating equation modeling. We used a large population-based clinical data born in British Columbia (BC) and linked the fetal-maternal data to hand-searched pathology reports of 1493 twin placentas from twins born in BC Women hospital. We analyzed the data using generalized estimating equations taking the cluster nature of twins into consideration.<bold>Results: </bold>About 26.5% of twins were monochorionic and 73.5% were dizygotic. Most twins were male (51.3%). About 2/3 of twins were sex concordant (66.6%). Of the sex concordant twins, similar percentages were male-male (34.7%) and female-female (31.2%). Of the sex discordant twins, the male-female (33.3%) group constituted about 1/3 of the whole population. Adjusted for chorionicity, birth weight discordance ≥30% and gestational age, the odds of chorionitis (1.38, 95% CI = 1.04-1.84), anastomosis (1.63, 95% CI = 1.22-2.19), unequal sharing of placenta (1.72, 95% CI = 1.11-2.64), placental inflammation (1.30, 95% CI = 1.05-1.62) and lesions (1.83, 95% CI = 1.02-3.31) were higher in male twins compared with females. Twins of either sex from sex-discordant pairs were less likely to have placental anastomosis compared to the reference category. Males from male-male pairs had higher odds of unequal placental sharing (74% higher) and composite inflammation (52% higher) compared with the reference twins.<bold>Conclusion: </bold>Our findings suggest a relationship between sex and placental pathological results. [ABSTRACT FROM AUTHOR]