Cumulative effects of prenatal phthalate and psychosocial stress exposure on infant neurodevelopment in an African American Maternal-Child cohort

• In Event: Effects of Environmental Exposures on Birth and Early developmental Outcomes

Abstract

Introduction: Prenatal exposure to phthalates, a group of synthetic chemicals widely used in everyday consumer products, has previously been associated with adverse infant and child neurodevelopment. Studies suggest that maternal exposure to psychosocial stressors, such as depression and experiences of discrimination, may amplify the harmful effects of phthalates on infant and child neurodevelopment. However, few studies have examined the cumulative effects of phthalates and psychosocial stressors together as an exposure mixture, which may better reflect real life exposure patterns.
Hypothesis: We hypothesized that the cumulative effects of phthalates, depression, and gendered racial stress on infant and child development would be greater than the effect of individual phthalate or stressors alone.
Study Population: Our analytic sample included 86 mother-infant dyads, a subset of participants enrolled in an African American Maternal-Child cohort.
Methods: Eight phthalate metabolites (MEP, MBP, MiBP, MBzP, MEHP, MEOHP, MEHHP, MECPP) were measured in first and second trimester maternal urine samples and were geometric averaged and natural log transformed for analysis. Validated questionnaires administered during the first trimester were used to assess maternal depression and gendered racial stress. The NICU Network Neurobehavioral Scale (NNNS) was administered at two weeks of age. Our primary outcomes included two composite NNNS scores reflecting newborn attention and arousal, defined using principal component analysis. Linear regression was used to estimate the effect of individual phthalates on newborn attention and arousal. Quantile g-computation was used to estimate the joint effects between phthalates and psychosocial stressors. All models were adjusted for creatinine, parity, maternal age, early pregnancy body mass index, maternal education, and any alcohol, tobacco, or marijuana use during pregnancy.
Results: Our analytic sample included a socioeconomically diverse group of pregnant people, with 79% receiving public health insurance and 52% married or living with a partner. Individual phthalate metabolites were not associated with infant attention or arousal in single pollutant models. Using quantile g-computation, a simultaneous one quantile increase in all phthalates, in combination with gendered racial stress and depression, was associated with a decrease in the composite NNNS reflecting reduced infant arousal (mean change per quartile increase = -0.38, 95% confidence interval [CI]= -0.81, 0.05). The phthalate and stress mixture was not strongly associated with infant attention (mean change per quartile increase = -0.11, 95% CI= -0.56, 0.34).
Conclusions: Applying methods designed for analyzing exposure mixtures, a simultaneous increase in intrauterine exposure to phthalates, depression, and gendered racial stress was found to be associated with worsening infant arousal.

Authors

• Jasmin Eatman
  Presenting Author

• Patricia Brennan, Emory University

• Dana Boyd Barr

• Elizabeth Corwin, Columbia University

• Donghai Liang

• Anne Dunlop, Emory University

• Stephanie M. Eick, Emory University