Transient reduction in fetal activity and heart rate variation after maternal betamethasone administration.

We studied the short-term effects of maternal betamethasone administration on fetal well-being by recording of fetal movement and heart rate patterns. In 13 women at high risk of preterm delivery (26-32 weeks), eighty 1-h recordings were made of fetal body and breathing movements and fetal heart rate (FHR) and its variation during 5 consecutive days. Betamethasone was administered in two doses 24 h apart after a control recording had been made. After two doses of betamethasone, fetal body and breathing movements and FHR variation were considerably reduced (P < 0.01), but returned to normal after treatment was discontinued. FHR variation was transiently below the lower normal range in 46% of the cases. We conclude that maternal betamethasone administration results in a considerable reduction in fetal movements and FHR variation which may erroneously be interpreted as deterioration of the fetal condition. Knowledge of these transient changes is of significant clinical importance as it may prevent iatrogenic delivery because of suspected fetal distress. The observed effects are possibly mediated by centrally located glucocorticoid receptors.

Changes with time in fetal heart rate variation, movement incidences and haemodynamics in intrauterine growth retarded fetuses: a longitudinal approach to the assessment of fetal well being.

Fetal heart rate (FHR) variation, general movements (FGM), breathing movements (FBM) and haemodynamics were studied longitudinally in 19 intrauterine growth retarded fetuses, who eventually were delivered by caesarean section (CS) because of fetal distress, in order to determine changes occurring with time. The fetuses were studied for the last 10 days on average before delivery (range 2-14 days). During this period on average eight 1-h FHR records were made and three 1-h movement recordings. The FHR pattern was analyzed numerically; the incidence of FGM and FBM was quantified and expressed as percentage of time. Blood flow velocity waveforms were measured in the umbilical artery (n = 19) and in the internal carotid artery (n = 14). In 14 of 19 fetuses abnormal velocity wave forms were present from the beginning of the study onwards. FHR variation was initially just within or below the norm and fell further during the last 2 days before CS. FGM and FBM fell below the normal range later and in a lower rate of occurrence than FHR variation. FGM showed a more or less consistent fall in time, whereas FBM showed a wide range throughout the period of observation. The poorest outcome occurred in fetuses with reversed end-diastolic velocities and rapid fall in FHR variation. It is concluded that with progressive deterioration of the fetal condition abnormal velocity wave form patterns occur first; FHR variation is reduced subsequently and FGM and FBM are the last to become abnormal. Assessment of fetal activity may be of help in fetuses with a marginally reduced FHR variation, in which prolongation of pregnancy is considered desirable to allow further maturation in utero.