Impact of Maternal Prenatal Psychological Stress on Birth Weight

Objective: The study aimed to evaluate the impact of prenatal maternal stress on birth weight using a large cohort of predominantly White women living in an urban area. Method: Women were recruited between 2005 and 2010. Data collection took place between the 24th and the 28th week of gestation. The Measure of Psychological Stress (MSP-9), a validated tool to assess stress symptoms, was used to collect data on prenatal maternal stress (independent variable). Birth weight (dependent variable) was classified as low birth weight (<2,500 g), normal birth weight (2,500-4,000 g), and macrosomia (>4,000 g). Adjusted odds ratios (aOR) were obtained after performing multivariate logistic regressions adjusted for potential cofounders. At the final stage, 5,721 women were included in analysis. Results: When compared with women experiencing low stress, participants with high stress scores were at increased risk of delivering a newborn with low birth weight before adjustment (OR = 2.06, 95% CI [1.04, 4.09]), but after adjustment, only a nonsignificant trend remained. However, women experiencing intermediate and high levels of stress were at increased risk of delivering a newborn with macrosomia, even after adjustment (aOR = 1.23, [1.02, 1.49]) and (aOR = 1.76, [1.11, 2.77]) compared to those who scored low on the psychological stress scale. Conclusion: Women exposed to high psychological stress during the second trimester (24th to 28th weeks) of pregnancy have a 1.8-fold increased risk for delivering a newborn with macrosomia when compared to women exposed to low psychological stress.