Heart rate variability during pregnancy moderates the impact of depressive symptoms on fetal growth

Depression occurs in up to 13 % of all pregnancies and is associated with adverse pregnancy outcomes. However, the literature regarding associations between depression and lower birth weight or fetal growth has been inconsistent. Here, we consider if high frequency heart rate variability (HF-HRV) may moderate the association between depression and birth weight. Lower HF-HRV has been associated with greater risk of depression and poorer health outcomes. However, during pregnancy, there is a normative decrease in HF-HRV that may be protective. Higher HF-HRV is associated with a person's ability to flexibly adapt to challenges. During pregnancy, less flexibility may reduce responses to challenges, including depression, thereby mitigating the vulnerability of the pregnancy to the effects of depression. The present study considers this possibility with 80 pregnant women who completed a measure of depressive symptoms during pregnancy at 24 to 28, 30 to 32, and 36 to 38 weeks gestation, and had HF-HRV measured at 24 to 28 weeks gestation. Fetal growth was derived using birth weight and length of gestation data gathered from medical charts. Results revealed that for women with higher HF-HRV, depressive symptoms were negatively associated with fetal growth. This relationship was not evident for women with lower HF-HRV, who appeared to be protected from the effects of depression on fetal growth. Considering the combined impact of HF-HRV and depression during pregnancy may help us better identify women at risk of having lower birth weight neonates, and improve our understanding of how depression is associated with adverse pregnancy outcomes.