Within-person changes of cortisol, dehydroepiandrosterone, testosterone, estradiol, and progesterone in hair across pregnancy, with comparison to a non-pregnant reference group.

The literature on hormone changes in pregnancy has focused largely on cortisol, and changes in sample average concentrations. Within-person changes and variability in hormone concentrations are less commonly reported, particularly for sex hormones, and especially measured in hair. Using a prospective sample of pregnant women and a non-pregnant comparison group, we examined changes in five steroid hormones in hair. Non-pregnant women were recruited from the same area with parallel procedures and assessment timeline. Participants include 68 women (34 pregnant, average age = 29.14, and 34 non-pregnant; average age = 27.18) who were predominately non-Hispanic White (83%), and above the 2020 poverty line (75%). Pregnant women provided 3cm hair samples and completed questionnaires three times during pregnancy: 1) at 12 weeks, 2) at 26 weeks, and 3) at 38 weeks. Non-pregnant women provided 3cm hair samples and completed questionnaires three times, at baseline, 14 weeks later, and 12 weeks after that to mirror the assessment schedule of the pregnant group. There was clear evidence that progesterone was higher initially and increased dramatically across pregnancy whereas non-pregnant patterns showed no systematic change. There was suggestive evidence that cortisol and estradiol increased over pregnancy and in non-pregnant women similarly across the same time course. There was suggestive evidence that DHEA decreased across pregnancy, particularly early in pregnancy, differently from patterns in non-pregnant women over the same time course. Most importantly, there was substantial variability of hormone concentrations and many different within-person patterns of changes in these hormones over time, with little evidence of systematic change or stability within-individuals. Moving beyond discussing sample averages to including within-person and non-linear changes in studies of hormones-behavior associations during pregnancy is an important future direction for further investigation.