Table 4.
Stage-of-pregnancy associations between PSS (Perceived Stress Scale) and cortisol: Results from linear mixed models predicting log-transformed AUC.g (area under the curve) averaged across four days by averaged PSS-EMA (Model A), PSS-past-4-days (Model B), and PSS-past-4-weeks (Model C) adjusted for gestation age (GA) and pre-pregnancy body-mass-index (BMI).
| MODEL A | ||||
|---|---|---|---|---|
| Fixed effects | ||||
| B (SE) | beta | 95% CI for B | p | |
| Intercept | 0.834 (0.120) | 0.598 –1.071 | <.001*** | |
| Level 1 | ||||
| PSS-EMA-4-day.cwc | 0.040 (0.041) | .026 | −0.041 – 0.122 | .330 |
| GA | 0.102 (0.006) | .459 | 0.090 – 0.114 | <.001*** |
| Level 2 | ||||
| Level 3 | ||||
| PSS-EMA.pm | 0.014 (0.044) | .019 | −0.073 – 0.101 | .758 |
| Pre-pregnancy BMI | −0.009 (0.004) | −.144 | −0.016 – −0.001 | .021* |
| Random effects | ||||
| Variance | SD | |||
| ID | 0.067 | 0.259 | ||
| Stage of pregnancy | 0.035 | 0.187 | ||
| Residual | 0.007 | 0.088 | ||
| MODEL B | ||||
| Fixed effects | ||||
| B (SE) | beta | 95% CI for B | p | |
| Intercept | 0.887 (0.122) | 0.647 – 1.127 | <.001*** | |
| Level 1 | ||||
| PSS-past-4-days.cwc | 0.032 (0.032) | .028 | −0.031 – 0.095 | .316 |
| GA | 0.104 (0.006) | .469 | 0.091 – 0.117 | <.001*** |
| Level 2 | ||||
| Level 3 | ||||
| PSS-past-4-days.pm | −0.034 (0.044) | −.049 | −0.122 – 0.053 | .439 |
| Pre-pregnancy BMI | −0.009 (0.004) | −.148 | −0.016 – −0.002 | .018* |
| Random effects | ||||
| Variance | SD | |||
| ID | 0.066 | 0.257 | ||
| Stage of pregnancy | 0.037 | 0.191 | ||
| Residual | 0.008 | 0.089 | ||
| MODEL C | ||||
| Fixed effects | ||||
| B (SE) | beta | 95% CI for B | p | |
| Intercept | 0.943 (0.127) | 0.694 – 1.192 | <.001*** | |
| Level 1 | ||||
| PSS-past-4-weeks.cwc | 0.013 (0.034) | .011 | −0.053 – 0.080 | .693 |
| GA | 0.103 (0.006) | .465 | 0.091 – 0.115 | <.001*** |
| Level 2 | ||||
| Level 3 | ||||
| PSS-past-4-weeks.pm | −0.060 (0.045) | −.083 | −0.149 – 0.028 | .180 |
| Pre-pregnancy BMI | −0.009 (0.004) | −.149 | −0.016 – −0.002 | .016* |
| Random effects | ||||
| Variance | SD | |||
| ID | 0.066 | 0.256 | ||
| Stage of pregnancy | 0.036 | 0.190 | ||
| Residual | 0.007 | 0.088 | ||
Note. Significance codes:
p > .01 ‘ ‘
p < .10 ‘.’
p < .05 ‘*’
p < 0.01 ‘**’
p < .001 ‘***’.
Results displayed for log-transformed AUC.g averaged across four days. Transformation did not change magnitude, direction nor significance level of the reported effects. Default covariance structure was chosen based on non-significant likelihood ratio test comparing different covariance structures. For fit indices, see Supplement Table S7.