Effect of weight gain during pregnancy on heart rate variability and hypotension during caesarean section under spinal anaesthesia.

Abstract

The purpose of this study was to assess the effect of antenatal weight gain on baseline heart rate variability and incidence of hypotension in singleton parturients with a normal pre-pregnancy body mass index, presenting at term for elective caesarean section under spinal anaesthesia. Sixty-six parturients, of ASA physical status 1-2, were allocated to one of three groups according to their weight gain during pregnancy: < 11 kg; 11-16 kg; and > 16 kg. Mean (SD) approximate entropy of baseline heart rate was significantly higher in the < 11 kg group (0.27 (0.11)) compared with the 11-16 kg group (0.14 (0.08)) and the > 16 kg group (0.14 (0.07)) (both p < 0.001). The incidence of hypotension in the < 11 kg group (17/22; 77%) was significantly higher than in the 11-16 kg group (7/22; 32%) (p = 0.006) and the > 16 kg group (8/22; 36%) (p = 0.01). We conclude that weight gain < 11 kg during pregnancy is associated with increased baseline heart rate variability and a higher incidence of hypotension at the time of elective caesarean section under spinal anaesthesia.