Third trimester cortisol is positively associated with gestational weight gain in pregnant women with class one obesity

Abstract

Background/objective: Prevalence of pre-pregnancy obesity and excessive gestational weight gain (GWG) are higher among women of color with low SES. Dysregulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis and its end-product, cortisol, during pregnancy is hypothesized to be associated with excessive GWG. However, past studies have produced inconsistent findings and often did not include health disparities populations. This study examined the association between pre-pregnancy body mass index (BMI), third trimester diurnal cortisol, and GWG in low-income, predominantly Hispanic women.

Subjects/methods: The MADRES study is an ongoing prospective cohort study of primarily Hispanic, low-income pregnant women and their children in Los Angeles, California. Data from 176 participants were included in this study. Total cortisol secretion (area under the curve, AUC) was quantified using four salivary cortisol samples (awakening, 30 min after awakening, afternoon, and bedtime) that were collected at home on one day during the third trimester of pregnancy. Moderation of the association between total cortisol and GWG by pre-pregnancy BMI was tested using multiple linear regression with a multiplicative interaction term.

Results: There was no association between total cortisol secretion and GWG overall (p = 0.82), but the association between total cortisol and GWG was stronger for women with class 1 pre-pregnancy obesity compared to women with normal pre-pregnancy BMI (interaction term p = 0.04).

Conclusions: Results suggest that obesity status before pregnancy may be exacerbating the physiological impact of cortisol on GWG.

Figure 1.

Consort Diagram of Included Observations Step by step data creation process illustrating included and excluded observations for final data set Note. Trendline was plotted using locally weighted scatterplot smoothing (LOESS) for each pre-pregnancy BMI category

Figure 2.

Total Gestational Weight Gain (GWG) by Pre-Pregnancy BMI Violin plot illustrating mean, standard deviation, and distribution of total GWG by pre-pregnancy BMI category Note. Dots are mean total GWG per pre-pregnancy BMI category; lines are standard deviation per pre-pregnancy BMI category

Figure 3.

Diurnal Cortisol Patterns by Pre-Pregnancy BMI

Figure 4.

Association of Third Trimester Area Under the Curve and Gestational Weight Gain by Pre-Pregnancy BMI Note: Model controlled for real-time personal monitoring sub-study participation (ref: not sub-study participant), gestational age at study entry, recruitment site (ref: LAC+USC), gestational age at birth, ethnicity by birthplace (ref: Non-Hispanic), highest education level (ref: High School), age, and third trimester nausea or vomiting (ref: no nausea or vomiting).