Maternal Weight, Weight Gain, and Metabolism are Associated with Changes in Fetal Heart Rate and Variability

OBJECTIVE

Prepregnancy obesity and extensive weight gain can lead to diseases in the offspring later in life. The aim of this study was to evaluate the effect of anthropometric and metabolic factors on the fetal autonomic nervous system (ANS) in uncomplicated pregnancies.

METHODS

A total of 184 pregnant women in the second or third trimester were included, and for 104 women, maternal insulin sensitivity (ISI) was determined. Fetal heart rate (HR) and heart rate variability (HRV) were determined by magnetic recording. Associations of maternal prepregnancy BMI, weight gain, and ISI with fetal HR and HRV were evaluated by ANCOVA, partial correlation, and mediation analysis.

RESULTS

HR was increased and HRV decreased in fetuses of mothers with overweight or obesity in comparison to normal-weight mothers. Fetal HR was negatively correlated with maternal weight gain. Maternal prepregnancy BMI was positively correlated with fetal high frequency and was negatively correlated with low frequency and low/high frequency ratio. Maternal ISI showed a negative correlation with fetal HR.

CONCLUSIONS

The results show that the fetal ANS is sensitive to alterations of prepregnancy BMI, weight changes, and glucose metabolism. These findings highlight the importance of the intrauterine environment on the developing ANS and the possible programming of obesity.

Central insulin administration improves whole-body insulin sensitivity via hypothalamus and parasympathetic outputs in men

Animal studies suggest that insulin action in the brain is involved in the regulation of peripheral insulin sensitivity. Whether this holds true in humans is unknown. Using intranasal application of insulin to the human brain, we studied the impacts of brain insulin action on whole-body insulin sensitivity and the mechanisms involved in this process. Insulin sensitivity was assessed by hyperinsulinemic-euglycemic glucose clamp before and after intranasal application of insulin and placebo in randomized order in lean and obese men. After insulin spray application in lean subjects, a higher glucose infusion rate was necessary to maintain euglycemia compared with placebo. Accordingly, clamp-derived insulin sensitivity index improved after insulin spray. In obese subjects, this insulin-sensitizing effect could not be detected. Change in the high-frequency band of heart rate variability, an estimate of parasympathetic output, correlated positively with change in whole-body insulin sensitivity after intranasal insulin. Improvement in whole-body insulin sensitivity correlated with the change in hypothalamic activity as assessed by functional magnetic resonance imaging. Intranasal insulin improves peripheral insulin sensitivity in lean but not in obese men. Furthermore, brain-derived peripheral insulin sensitization is associated with hypothalamic activity and parasympathetic outputs. Thus, the findings provide novel insights into the regulation of insulin sensitivity and the pathogenesis of insulin resistance in humans.