Pre-pregnancy obesity and maternal circadian cortisol regulation: Moderation by gestational weight gain

• Pre-pregnancy obesity, gestational weight gain, and diurnal salivary cortisol interact.
• Findings were significant in a socioeconomically at-risk sample in late pregnancy.
• Women obese prior to pregnancy who gained in excess of IOM guidelines had greater evening cortisol at 35 ± 1 weeks gestation.
• No such patterns were found at 24 ± 4 weeks gestation, in non-obese women, or in those within IOM recommendations.

We investigated main and interactive effects of maternal pre-pregnancy obesity and gestational weight gain on circadian cortisol from the second to third trimester. A diverse sample of 215 pregnant women was enrolled. Maternal height and most recent pre-pregnancy weight were collected at study initiation (22% obese). Weight and circadian salivary cortisol samples were measured during second (24 ± 4) and third (35 ± 1 weeks) trimesters. During the third trimester, women who were obese prior to conception showed elevated evening cortisol versus normal weight women. This pattern was moderated by weight gain in excess of Institute of Medicine guidelines, such that women who were obese prior to conception and gained greater than 7.94 kg by the 35 ± 1 week visit displayed greatest elevations in evening cortisol. Given links between excessive prenatal glucocorticoid exposure and both poor maternal and offspring health outcomes, elevated maternal cortisol may be one mechanism underlying links between maternal obesity and adverse perinatal outcomes.