Causes of fetal death in women of advanced maternal age

To examine which causes of fetal death occur more often in older women and to determine whether these causes have changed significantly since the 1960 s and early 1970 s.

Data from the McGill Obstetrical Neonatal Database were used to calculate rates of specific causes of fetal death in women younger than 35 and in women 35 years or older. Among the 101,640 births between 1961 and 1995, there were 715 stillbirths and 822 neonatal deaths. The autopsy rate was 97% and categorization of the causes of fetal death remained consistent over this 34-year period. The rates of specific causes of fetal death per 10,000 total births were determined for an earlier period (1961-1974) and a later period (1978-1995).

Compared with the 1961-1974 period, there was a 60% reduction in the rates of both fetal and neonatal deaths during 1978-1995 (P < .001). During 1961-1974, women 35 years or older were more likely than their younger counter-parts to have fetal death due to lethal congenital anomalies (odds ratio [OR] 3.2; 95% confidence interval [CI] 1.5, 6.5); this was no longer true in the 1978-1995 period. From 1978 to 1995, older women were at a statistically significant increased risk for "unexplained" fetal death (OR 2.2; 95% CI 1.3, 3.8); women 35 years of age or older had approximately one in 440 births end in unexplained fetal death, compared to one in 1000 births for women younger than 35.

Advanced maternal age is no longer associated with an increased risk for fetal death due to congenital anomalies. However, older women have a significantly higher risk for unexplained fetal death. The identification of those maternal and fetal characteristics that contribute to unexplained fetal death and its prevention remain important challenges for contemporary obstetric practice.