Bottoms Down: Can Risk for Breech Birth Be Inherited?

Clinical factors associated with breech presentation — such as uterine abnormalities, site of placental attachment, congenital abnormalities, maternal age, and infant birth weight — are identified in only 7%–15% of breech deliveries. To test the hypothesis that risk for breech delivery has an inherited component, investigators used birth registries in Norway to link 233,000 mother-offspring and 155,000 father-offspring breech delivery pairs; the first generation was born from 1967 through 1986 and the second from 1987 through 2004.

Breech births accounted for 2.5% of deliveries from 1967 through 1976; the rate increased by 0.2%–0.5% each decade and reached 3.5% from 1997 through 2004. Babies whose fathers or mothers were delivered breech at …