Table 2.

Results of piecewise linear mixed effects model of trajectory of hair cortisol concentration across the peripartum period. HCC was log-transformed and all variables were then standardized prior to analysis. ICC = intraclass correlation coefficient. Prenatal slope captures rate of change in log(HCC) from conception to childbirth. Postnatal slope captures rate of change in log(HCC) from childbirth to six months postpartum. Number of participants = 85. Number of observations = 783. Marginal R²/Conditional R² = 0.04/0.90.

Predictors	$\beta$	95% CI	p
(Intercept)	0.18	0.01, 0.36	.041
Prenatal slope	0.24	0.16, 0.33	<.001
Postnatal slope	−0.20	−0.28, −0.12	<.001
Random effects
(Intercept)	0.71
Prenatal slope	0.23
Postnatal slope	0.05
Hair segment	0.08
Residual	0.11
ICC	0.90