Risk of stillbirth in older mothers: a specific delivery plan might be considered for prevention

In recent decades, the trend for women is to delay childbearing. However, worldwide, advanced maternal age is an independent risk factor for stillbirth, as well as advanced gestational age. National data are not available about stillbirths in the Italian population. We explored whether, at term of pregnancy, advanced maternal age is associated with an increased risk of stillbirth in Italy. We speculate that a policy of induction of labor at term of pregnancy in older mothers may significantly reduce the stillbirth.

Data provided by Italian Ministry of Health and National Statistical Institute were used to identify all singleton deliveries ≥22 weeks of gestation during a four years study period. We evaluated the outcome of pregnancy (livebirths or stillbirths) and we stratified data by gestational age and by maternal age at delivery. The hazard risk and the relative risk of stillbirth were calculated.

The overall stillbirth rate was 3.4 per 1000, with a total of 6451 cases of stillbirths in the four years study period. Overall, the risk of stillbirth increases at term of pregnancy in all maternal age groups, especially in older mothers. A total of 674 stillbirths occurred in women aged 40 years or older and 24.2% of them (n = 163) occurred at term of pregnancy. Among women aged 40 years and above, 7.3% of stillbirths (49/674) occurred beyond 39 weeks of gestation. The hazard risk doubles from 39 to 40 weeks, from 0.60 per 1000 ongoing pregnancies to 1.16 per 1000 ongoing pregnancies; the relative risk at 40 weeks of gestation was the highest in the older mothers and was 5.17 (95% CI 3.16-8.46).

The effect of maternal age on birth outcomes is a relevant aspect in Italy. If the association between maternal age and stillbirth is supposed to be part of the pathophysiology of fetal death, our data indicate that induction of labor before 40 weeks of gestation in women aged 40 years old or older might prevent overall 7.3% of stillbirths for induction at 39 weeks, 13% of stillbirths for induction at 38 weeks. To reduce potentially preventable stillbirths, caregivers should perform a specific risk assessment for each pregnant woman. The impact of maternal age should be seriously considered, and an individualized approach should be planned at term of pregnancy in older mothers, including the possibility of a slightly anticipation of induction of labor if spontaneously undelivered.