Reduced gestational cortisol levels linked to higher BMI and weight gain: Evidence from a pupulation-based cohort in...

During pregnancy, inadequate body mass index (BMI) and cortisol levels can pose health risks to both the mother and the fetus. So, the relationship between BMI and serum cortisol levels were investigated throughout gestation in a population-based cohort of pregnant women in southern Brazil. Pregnant women up to 24 weeks of gestation were assessed at the time of identification and again 60 days following the initial interview. Blood samples for cortisol measurement by ELISA were collected at both assessments. Evaluation of 717 participants showed increases in both cortisol and BMI levels along the progression of the gestation (r = 0.282; p < 0.001). Notably, adjusted mixed-effect linear regression showed that the interaction between gestational week and pre-gestational BMI did not significantly modify cortisol levels throughout gestation (B: -0.00014; 95 % CI: -0.00035; 0.00007; p = 0.205). However, BMI from the first evaluation (B: -0.00022; 95 % CI: -0.00043; -0.00001; p = 0.038) and gestational BMI (B: -0.00031; 95 % CI: -0.00051; -0.00011; p = 0.002), reveals that BMI during pregnancy can be a predictor of a discrete reduction in cortisol levels. Moreover, gestational weight gain along pregnancy are also associated with reduced levels of maternal cortisol (B = -0.00044; 95 % CI: -0.00063 to -0.00025; p < 0.001). These findings suggest that while cortisol levels rise during pregnancy, this increase is attenuated in women with higher gestational BMI or higher weight gain along gestational period. This may suggest a hyporeactive hypothalamic-pituitary-adrenal (HPA) axis in individuals with higher BMI, underscoring the complex interplay between metabolic and endocrine factors during gestation.