Late stillbirths (> 28 weeks' gestation) affect 1 in 300 pregnancies in New Zealand: this equates to approximately 200 deaths a year. This loss of life and the adverse psychological impact is a silent epidemic. There has been minimal decrease in stillbirth in New Zealand in the last two decades. The Auckland stillbirth study found that late stillbirths were increased in mothers who did not sleep on their left side. If there is a causal relationship between maternal sleep position and late stillbirth, we estimate that approximately one third of late stillbirths (up to 70 deaths annually) might be prevented by mothers sleeping on their left sides. This novel finding needs to be confirmed or refuted (in the proposed study) to ascertain whether a preventative programme should be introduced. This study will recruit 290 women with late stillbirths and 580 with ongoing pregnancies (controls) from New Zealand's largest maternity units.