Relationship Between Endocannabinoids During Pregnancy and Infant Heart Rate and Heart Rate Variability

Maternal factors during pregnancy affect fetal and infant heart rate (HR) and heart rate variability (HRV), clinical indices of early life autonomic development. Although there is an established relationship between maternal n-3 long chain polyunsaturated fatty acid (LCPUFA) intake and early life HR and HRV, the mechanism has not been elucidated. It is plausible that in utero exposure to specific endocannabinoids, dictated in part by maternal nutrition, underlie previous observations. The relationship between circulating endocannabinoids, HR, and HRV at any life or physiological stage has not been assessed. This study explored the relationship between in utero exposure to endocannabinoids and infant HR and HRV. Mother-infant pairs (n = 11) were recruited before 20 gestational weeks. Circulating n-6 and n-3 fatty acid related endocannabinoids were quantified in maternal plasma at 20, 24, 32, and 36 gestational weeks and umbilical cord venous plasma at term delivery. Infant HR and HRV were assessed at 2 weeks, 4 months, and 6 months of age using 24 h continuous ambulatory electrocardiograph monitoring. Regression analyses were used. In general, maternal and umbilical cord n-3 endocannabinoids were inversely related to infant HR and positively related to HRV. When the ratio of n-6 to n-3 endocannabinoids reflected greater presence of the n-6 series, there were positive relationships with infant HR and inverse with HRV. These data indicate, but do not definitively conclude, that in utero exposure to endocannabinoids may contribute to programming the developing autonomic nervous system which is clinically reflected as decreased HR and increased HRV. Future studies focused on autonomic development and function should include an assessment of endocannabinoid status.