Maternal corticotropin-releasing hormone and habituation in the human fetus

Elevated concentrations of maternal corticotrophin-releasing hormone (CRH) during the 2nd and early 3rd trimester of human pregnancy are associated wi th spontaneous preterm birth, but the effects of maternal CRH on the fetus are unknown. Maternal plasma was collected for analysis of CRH concentratio n, m = 156.24 +/- 130.91 pg/ml, front 33 pregnant women during Weeks 31-33 of gestation. Immediately after collection of plasma, fetal heart rate (FHR ) measures were obtained in response to a challenge with a series of vibroa coustic stimuli. Fetuses of mothers with highly elevated CRH did not respon d significantly to the presence of a novel stimulus in a repeated series, p = 0.016. These effects on the FHR response were not related to parity, fet al gender, medical (antepartum) risk, or eventual birth outcomes. Impaired dishabituation in these fetuses of mothers with high concentrations of CRH suggests that neurological systems rich with CRH receptors that support lea rning and memory, such as parahippocampal regions, may be targets for mater nal/placental CRH, with implications for fetal neurological development. (C ) 1999 John Wiley & Sons, Inc.