Independent effects of depression and elevated body mass index on maternal CRP levels in pregnancy

Perinatal depressive symptoms and elevated pre-pregnancy BMI associate with gestational inflammation, however it remains unclear whether these are distinct effects. We examined whether maternal depressive symptoms, pre-pregnancy BMI and their interactions associated with maternal C-Reactive Protein (CRP) levels in early and/or later pregnancy in 383 women participating in the Ontario Birth Study.

Maternal depression was measured at weeks 12-16 and 28-32 gestation using the PHQ-2, while pre-pregnancy BMI was calculated based on retrospective self-reports. Maternal plasma CRP was measured at 14.4 +/- 1.9 and 27.0 +/- 1.3 weeks gestation. Separate multiple regressions were used to predict the two log-transformed CRP levels with the two pregnancy PHQ-2 scores at step 1, then adding pre-pregnancy BMI at step 2 and the PHQ-2 X BMI interaction terms at step 3.

PHQ-2 scores at weeks 12-16 were significantly associated with logCRP levels measured at the later but not earlier pregnancy time point (standardized beta = 0.09, t = 2.29, p = .022), while PHQ-2 scores at weeks 28-32 did not associate with either logCRP level. Pre-pregnancy BMI was significantly associated with logCRP in early and later pregnancy. The link between early PHQ-2 scores and later pregnancy CRP was not weakened when pre-pregnancy BMI was entered at step 2. Neither of the PHQ-2 X BMI interactions was significantly associated with maternal CRP levels.

The current data suggest that PHQ-2 scores in early pregnancy predict higher maternal CRP, but only after a time lag, while elevated BMI has a separate, more consistent effect on CRP across pregnancy.