Women who continue their pregnancy to 41 weeks have a small but significantly increased risk of stillbirth, according to a meta-analysis covering more than 15 million pregnancies.

For the first time, researchers have quantified how the risk of stillbirth and neonatal death increases with gestational age, finding one additional stillbirth for every 1449 pregnancies with delivery at 41 weeks compared with 40 weeks.

With every week that a low-risk pregnancy continues past term, the risk of stillbirth increases by 29% at week 37, to 32% by week 38, to 64% at weeks 39 and 40, to 94% at 41 weeks. 

Lead researcher Professor Shakila Thangaratinam, from Queen Mary University of London, says the magnitude of the increasing risk is not routinely communicated to pregnant women.