Re: Maternal age and adverse pregnancy outcome: a cohort study. A. Khalil, A. Syngelaki, N. Maiz, Y. Zinevich and K. H. Nicolaides. Ultrasound Obstet Gynecol 2013; 42: 634–643



Linked Comment: Ultrasound Obstet Gynecol 2013:42:634–643

This paper studies the relationship between maternal age and pregnancy complications in almost 80 000 pregnancies, an important topic given the constant rise in maternal age observed over recent years, particularly in high-income countries. Evidence in the literature is conflicting, especially regarding a direct link between advanced maternal age and the risk of spontaneous preterm delivery or stillbirth. The study confirms a known and clear association between maternal age and a wide range of pregnancy complications, including miscarriage, pre-eclampsia, having a small-for-gestational age fetus, gestational diabetes and Cesarean section. More importantly, the results show that, after adjustment for pregnancy disorders, the risk of spontaneous preterm delivery or stillbirth is not associated with maternal age per se. The strengths of this study are the large sample size, the relatively low rate of loss to follow-up and the rigorous analysis of data collected prospectively. Some limitations were correctly acknowledged by the authors, including the lack of data on the women's level of education and socioeconomic status.

The relationship between advanced maternal age and the risk of stillbirth is highly controversial. The question is important because an increased risk of stillbirth with delayed childbearing, especially in term pregnancies, could indicate a need for change in the management of prolonged pregnancies and earlier intervention in at-risk women. The findings of this study regarding the risk of stillbirth are in disagreement with those of some larger population-based studies, conducted mostly in the USA, which concluded that advanced maternal age is an independent predictor of stillbirth, especially in term and post-term pregnancies[1-3]. Although the current study includes 76 158 singleton pregnancies and 290 stillbirths, a lack of statistical power cannot be excluded, given the relatively low number of stillbirths as compared with population-based reports. Given this limitation, this study cannot draw definitive conclusions about the etiology or timing of perinatal mortality in cases of advanced maternal age. One could also postulate that differences in perinatal care in the UK vs the USA might lead to different results in perinatal health, a hypothesis which deserves further study.