Lack of relationship between diurnal rhythms in fetal heart rate and maternal cortisol concentration

n 9 pregnancies complicated by intrauterine growth restriction, 24-hour fetal heart rate recordings were made before and after betamethasone treatment to study the influence of cortisol on diurnal fetal heart rate rhythms. Maternal and fetal rhythms were correlated and did not change after betamethasone administration. We conclude that diurnal fetal heart rate rhythms are synchronized by the mother through a mechanism other than adrenal control. (Am J Obstet Gynecol 2000;183:460-1.)