Stress during late pregnancy may result in premature delivery or stillbirth. A new study of pregnant Rambouillet cross ewes, published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, was designed to understand why lambs succumb to stress late in pregnancy. They found that while arterial blood pressure and heart rates were normal during late gestation (final 2 weeks before birth) in fetuses from pregnant ewes with elevated stress hormones, fetal heart rate and aortic blood pressure declined on the day of delivery. In fact, the greatest declines were measured during the final hour and shortly after delivery. These changes in the lambs can result in heart failure, which is thought to be a reason why maternal stress increases the risk for perinatal death.
A Antolic, CE Wood, M Keller-Wood. Chronic maternal hypercortisolemia in late gestation alters fetal cardiac function at birth. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 314(3): R342-352, 2018.