  It has been found that the effect of childhood trauma (CT) exposure may pass
on to the next generation. Scientists have hypothesized that the association
between CT exposure and placental-fetal stress physiology is the mechanism. A
study was conducted to examine the hypothesis. To examine the association
between CT exposure and placental corticotrophin-releasing hormone (pCRH),
linear mixed effect model and hierarchical Bayesian linear model were
constructed. In Bayesian inference, by providing conditionally conjugate
priors, Gibbs sampler was used to draw MCMC samples. Piecewise linear mixed
effect model was conducted in order to adjust to the dramatic change of pCRH at
around week 20 into pregnancy. Pearson residual, QQ, ACF and trace plots were
used to justify the model adequacy. Likelihood ratio test and DIC were utilized
to model selection. The association between CT exposure and pCRH during
pregnancy is obvious. The effect of CT exposure on pCRH varies dramatically
over gestational age. Women with one childhood trauma would experience 11.9%
higher in pCRH towards the end of pregnancy than those without childhood
trauma. The increase rate of pCRH after week 20 is almost four-fold larger than
that before week 20. Frequentist and Bayesian inference produce similar
results. The findings support the hypothesis that the effect of CT exposure on
pCRH over GA exists. The effect changes dramatically at around week 20 into
pregnancy.
