Prenatal exposure to perceived stress, maternal asthma, and placental size

Prenatal exposure to stress has been associated with poor pregnancy outcomes, yet evidence linking stress and placental size is limited. Asthma is associated with worse pregnancy outcomes and women with asthma may be more susceptible to stress. Using the asthma-enriched B-WELL-Mom cohort, we examined the association between perceived stress and placental size.

Placental measures of weight, length, width, and thickness were available for 345 women (262 with asthma) via placental pathology report. Perceived Stress Scale (PSS) scores were obtained in each trimester of pregnancy and categorized into quartiles (low quartile as reference). For associations between PSS and placental size, generalized estimating equations adjusted for maternal and infant factors were used to estimate regression coefficients (β) and 95% confidence intervals (95% CI). Full models and models stratified by asthma status were run.

Compared to Quartile 1, high levels of stress (Quartile 4) were associated with smaller placental weight (-20.63 95% CI: -37.01,-4.26) and length (-0.55 95% CI: -0.96,-0.15), but not width or thickness. Results by asthma status show a stronger association between perceived stress and shorter placental length in those with asthma and a stronger association between perceived stress and smaller placental thickness in those without asthma. Findings were robust to sensitivity analyses DISCUSSION: Higher levels of perceived stress were associated with smaller placental size. Additional research is warranted to understand the relationship between stress and placental size.