African American women with prenatal psychiatric disorder: Protein intake protects fetus from compromised birth weight and shortened gestation

Neuroendocrine stress hormones have been associated with both psychiatric disorders and poor birth outcomes. Recently, rat studies indicated protein intake below pregnancy recommendations interferes with an enzyme that blocks cross-placental transfer of maternal cortisol. This study tests the hypothesis that prenatal psychiatric disorder is more strongly associated with lower birth weight and shorter gestational length when protein intake is below the pregnancy RDA. In a prospective cohort of WIC-enrolled pregnant women, we analyzed data from 500 women. More than a quarter of women reported protein intake below 85% of the pregnancy RDA and 16% of births were preterm (<37 weeks). The Diagnostic Interview Schedule (DIS-IV), a structured diagnostic interview, assessed 22 current and lifetime diagnoses. Psychiatric disorders were operationalized as 'any current disorder' and 'lifetime symptoms above the 75th percentile' (chronicity and severity). Protein intake at WIC entry, as percent of RDA, was determined using the Harvard Food Frequency Questionnaire. Analyses using multiple linear regression, adjusted for mother's age, income, parity, and pre-pregnancy body mass, indicate significant interactions between RDA and both high lifetime symptoms and 'any disorder' for birth weight (p=.001 and p=.003) and length of gestation (p=.004 and p=.009) among African American but not Caucasian women. Effects show birth weight and gestational age to be compromised when a woman with a psychiatric disorder consumes less than 85% of the RDA. This study suggests pregnancy recommended protein intake may protect offspring of African American women with prenatal psychiatric disorders from associated effects of lower birth weight and shorter gestation.