213-POS

Abstract

Objectives To assess the degree of sexual dimorphism for Preterm Birth (PTB), Pregnancy Induced Hypertensive Disorders (PIHD) and Gestational Diabetes Mellitus (GDM) in an Australian population. Methods Retrospective population-based study of 574,358 South Australian singleton live births during 1981–2011 in the South Australian Perinatal Statistics Collection of three major adverse pregnancy outcomes (PTB (divided by PTB [birth before 37 weeks] and ePTB [birth before 34 weeks]), PIHD and GDM) in relation to fetal sex. Results There were 295,724 male (51.5%) and 278,634 (48.5%) female neonates (sex-ratio 1.06). Among all pregnancies there was a significant male dominance in pregnancies complicated by PIHD (RR 1.053, 95%-CI 1.034–1.072), PTB (PTB – RR 1.115, 95%-CI 1.092–1.139 & ePTB – RR 1.151, 95%-CI 1.104–1.199) and GDM (RR 1.042, 95%-CI 1.011–1.074). The pattern for PIHD by gestational age was markedly different (Fig. 1). Preterm PIHD showed a significant female dominance [RR’s ranging from 0.686, 95%-CI 0.581–0.811 (25–29 weeks) to 0.925, 95%-CI 0.870–0.982 (34–36 weeks)], while term PIHD showed a significant male dominance [RR 1.064, 95%-CI 1.037–1.093 (37–39 weeks) and RR 1.074, 95%-CI 1.044–1.105 (40–42 weeks)]. Conclusions This large South Australian cohort confirms the presence of marked sexual dimorphism for PTB, PIHD and GDM. The striking associations of male fetal sex with PTB and female sex with preterm PIHD could indicate that a certain degree of placental dysfunction in the male fetus would lead to PTB while the female fetus may be able to temporarily improve intrauterine life by increasing maternal blood pressure and thereby placental perfusion pressure with the attendant risk of PIHD. Disclosures P.E. Verburg: None. G. Tucker: None. W. Scheil: None. J.H. Erwich: None. C.T. Roberts: None. G.A. Dekker: None.