The effect of maternal obesity and lipid profile on first-trimester serum progesterone levels

Prepregnancy overweight increases the risk of adverse perinatal outcomes. Maternal lipid profile plays a key role in the production of pregnancy hormones. The influence that obesity has on the specific mechanisms that may be involved and the potential associations with abnormal conditions in pregnancy are still poorly understood.

This study aimed to evaluate the effect of maternal body mass index and lipid profile on first-trimester serum progesterone levels.

This was a prospective cohort study including 734 pregnant people. First-trimester maternal serum progesterone, cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides were measured between 9 and 11 weeks' gestation. Free β-hCG, PAPP-A, age, body mass index, smoking status, gestational age at delivery, fetal sex, and birthweight were also recorded. Pregnant people were classified according to their body mass index into underweight (n=21), normal weight (n=395), overweight (n=221), obesity class I (n=64), and obesity class II/III (n=33) groups.

Gestational age at sampling was 10.0 4±1.12 weeks. Serum progesterone levels decreased as maternal body mass index increased (35.84±12.00 ng/mL, 33.08±11.27 ng/mL, 28.04±8.91 ng/mL, 24.37±8.56 ng/mL, and 19.87±11.00 mL for underweight, normal weight, overweight, obesity class I, and obesity class II/III groups, respectively; P<.000001). There were statistically significant negative correlations between maternal progesterone and body mass index, triglycerides, and cholesterol/high-density lipoprotein cholesterol ratio, and positive correlations with gestational age at sampling, maternal age, cholesterol, high-density lipoprotein cholesterol, crown-rump length, free β-hCG, and PAPP-A. Linear regression showed that the only independent predictor variables for progesterone levels were body mass index (P<.0001), PAPP-A (P<.0001), high-density lipoprotein cholesterol (P<.0001), and free β-hCG (P<.0001) (R2=0.33; P<.0000001).

First-trimester serum progesterone levels were lower in overweight pregnant people and markedly decreased in those with obesity, especially obesity class II/III. Maternal high-density lipoprotein cholesterol was independently related to progesterone levels as a protective factor. Benefits of progesterone supplementation in pregnant people with obesity need further evaluation.