Blood pressure and HR in the fetal lamb: relationship to hypoglycemia, hypoxemia, and growth restriction.

Abstract

We examined blood pressure and heart rate (HR) in relation to glucose and arterial PO2 (PaO2) at approximately 121 days (early) and at approximately 140 days (late) gestation in 12 growth-restricted and 10 control fetal lambs. Mild growth restriction (relative to maternal weight) was produced by withdrawal of 25 ml/day of maternal blood during the second half of pregnancy (P < 0.05). Fetuses from this model are hypoglycemic during early and late gestation but hypoxemic only during late study. Mean systolic and diastolic pressures in the experimental group were approximately 8.0 mmHg lower than the corresponding values in controls at both studies (P < 0.05). Fetal HR (FHR) was 15.4 beats/min lower (P < 0.05) in 10 but was higher than control in 2 experimental fetuses that were also not growth restricted. There were significant correlations between late systolic pressure and HR and PaO2 (r = 0.54, P = 0.046 and r = 0.50, P = 0.049, respectively) and between FHR and blood pressure and birth weight/maternal weight (P < 0.05). We conclude that, in this model, fetal blood pressure and HR may serve as good indicators of hypoxemia and growth restriction.