The impact of maternal age on fetal death: does length of gestation matter?

The objective of the investigation was to study the association of fetal death with maternal age by length of gestation.

This was a population study including all ongoing pregnancies after 16 weeks of gestation in Norway during the period 1967-2006 (n = 2,182,756).

The risk of fetal death was 1.4 times higher in women 40-44 years old than in women aged 20-24 years in midpregnancy but 2.8 times higher at term. In term pregnancies the relative importance of maternal age increased by additional pregnancy weeks. In gestational weeks 42-43, the crude risk was 5.1 times higher in mothers 40 years old or older. In the recent period, the elevated risk of fetal death in elderly mothers at term has been attenuated.

Women 40 years old or older had the highest risk of fetal death throughout pregnancy, particularly in term and postterm pregnancies. Improved obstetric care may explain the attenuation of risk associated with age in recent time.