Male sex and pre-existing diabetes are independent risk factors for stillbirth.

Aim: To determine whether the risk of stillbirth is associated with male fetal sex, fetal growth and maternal factors in an Australian population.

Methods: A retrospective secondary data analysis of 16 445 singleton births was performed using a tertiary referral centre obstetric database (1995-1999). Univariate and multiple logistic regression analyses were performed.

Results: Stillbirth complicated 1% of the pregnancies in the study population, and 59% of stillbirths were associated with a male fetus. Significant characteristics associated with stillbirth were intrauterine growth restriction (IUGR), birth defects, gestational age, Aboriginal ethnicity, previous stillbirth, parity greater than three and placental abruption. Male stillbirths were more likely to occur at a later gestation (median gestation 30.5 weeks, range 20-43 weeks) compared to females (median 25 weeks, range 20-40 weeks), P = 0.01. Sixty per cent of IUGR fetuses were female (P < 0.001). Male sex (odds ratio (OR) 1.5, confidence interval (CI) 1.01, 2.17, P = 0.04) and maternal type 1 diabetes (OR 4.7, CI 1.58, 14.19, P = 0.006) were independently associated with stillbirth.

Conclusion: Male fetal sex and pre-existing diabetes are independent risk factors for stillbirth. Diabetes remains a significant risk for stillbirth even with contemporary monitoring and clinical management. Those diabetic pregnancies where the fetus is male require appropriate monitoring and timely interventions to achieve an optimal outcome.