Gestational age-specific risk of stillbirth during term pregnancy according to maternal age.

Purpose: To investigate the gestational age-specific risk of stillbirth according to the maternal age group particularly regarding stillbirth risk at the end of pregnancy.

Methods: This study was a retrospective national cohort study of all singleton term pregnancy using the Korean Vital Statistics database (n = 2,798,542). We evaluated the risk of stillbirth by gestational week in mothers aged 20-49 years according to maternal age group and neonatal birth weight.

Results: The risk of stillbirth in women aged 41 years and older was significantly higher than in women aged 20-29 years between 37 and 40 weeks' gestation. The stillbirth rate per 10,000 ongoing pregnancy in women aged 37-38 years at 39 weeks' gestation (4.22, 95% confidence intervals [CI] 3.01-5.90) and that in women aged 39-40 years at 40 weeks' gestation (8.15, 95% CI 4.83-13.77) were significantly higher in comparison with in those aged 20-29 years at 39 weeks' gestation (1.95, 95% CI 1.64-2.33) and at 40 weeks' gestation (2.59, 95% CI 2.1-3,18). The risk of stillbirth showed an increasing pattern at 40 gestational weeks, in women aged 39 years and older.

Conclusions: Delivery plan need to be set up and supported to decrease rates of stillbirth at term in women aged 35 years and older with other risk factors and in women aged 37 years and older regardless of risk factors, and especially in women older than 40 years of age.