Are there gender-specific differences in pregnancy outcome and placental abnormalities of pregnancies complicated with small for gestational age?

Introduction: Adaptations to pathological intrauterine environment might differ in relation to fetal gender. We aimed to study sex-specific differences in placental pathology of pregnancies complicated by small for gestational age (SGA). Methods: The medical records and placental histology reports of all neonates with a birth-weight ≤ 10th percentile, born between 24 and 42 weeks of gestation, during 2010–2018, were reviewed. Composite neonatal outcome was defined as one or more of early following complications: neonatal sepsis, blood transfusion, phototherapy, respiratory morbidity, cerebral morbidity, necrotizing enterocolitis, or death. Results were compared between the male and female groups of neonates. Placental lesions were classified into maternal and fetal vascular malperfusion (MVM and FVM) lesions, maternal and fetal inflammatory responses (MIR and FIR), and villitis of unknown etiology (VUE). Results: The male SGA group (n = 380) and the female SGA group (n = 363) did not differ in regard to maternal age, BMI, smoking, associated pregnancy complications, gestational age, and mode of delivery. Neonates in the SGA male group had increased birth-weight and increased respiratory morbidity as compared to the female SGA group (p = 0.007, p = 0.005, respectively). There was no between-group differences in the rate of placental lesions. By multivariate logistic regression analysis, male gender (aOR 1.55, 95% CI 1.05–2.30, p = 0.025), FIR (aOR 4.83, 95% CI 1.07–13.66, p = 0.003), and VUE (aOR 1.89, 95% CI 1.03–3.47, p = 0.04), were found to be independently associated with adverse composite neonatal outcome. Discussion: Male gender as well as placental FIR and VUE are independently associated with adverse neonatal outcome in SGA neonates.