Periconceptional diet quality is commonly suboptimal and sociodemographic disparities in diet quality exist. However, it is unknown whether individual periconceptional diet quality is associated with obstetric outcomes.Our objective was to assess differences in maternal and neonatal outcomes according to maternal periconceptional diet quality.This is a secondary analysis of a large, multicenter prospective cohort study of 10,038 nulliparous women receiving obstetrical care at 8 United States centers. Women underwent three antenatal study visits and had detailed maternal and neonatal data abstracted by trained research personnel. In the first trimester (between 6 and 13 weeks), women completed the modified Block 2005 Food Frequency Questionnaire, a semiquantitative assessment of usual dietary intake for the 3 months around conception. Responses were scored using the Healthy Eating Index-2010, which assesses adherence to the 2010 Dietary Guidelines for Americans. Higher scores on the Healthy Eating Index represent better adherence. Healthy Eating Index scores were analyzed by quartile; quartile 4 represents the highest dietary quality. Bivariable and multivariable analyses were performed to assess associations between diet quality and outcomes. A sensitivity analysis in which markers of socioeconomic status were included in the multivariable Poisson regression models was performed.In the cohort of 8,259 women with Healthy Eating Index data, the mean Healthy Eating Index score was 63 (± 13) of 100. Women with the lowest quartile Healthy Eating Index scores were more likely to be younger, non-Hispanic black and Hispanic, publicly insured, low income, and tobacco users. They were more likely to have comorbidities (obesity, chronic hypertension, pregestational diabetes, mental health disorders), a higher pre-pregnancy body mass index, and less education. Women with lowest quartile scores experienced less frequent major perineal lacerations and more frequent postpartum hemorrhage requiring transfusion and hypertensive disorders of pregnancy, which persisted on multivariable analyses (controlling for age, body mass index, tobacco use, chronic hypertension, pregestational diabetes mellitus, and mental health disorders) comparing women in each quartile to quartile 4. Additionally, women in quartiles 1 and 2 experienced greater adjusted relative risk of cesarean delivery compared to women in quartile 4. Neonatal outcomes also differed by dietary quartile, with women in the lowest Healthy Eating Index quartile experiencing greater adjusted relative risk of preterm birth, neonatal intensive care unit admission, small for gestational age infant, and low birthweight, and lower risk of macrosomia; all neonatal findings also persisted in multivariable analyses. The sensitivity analysis with inclusion of markers of socioeconomic status (race/ethnicity, insurance status, marital status) in the multivariable models supported these findings.Periconceptional diet quality among women in the United States is poor. Poorer periconceptional dietary quality is associated with adverse maternal and neonatal outcomes even after controlling for potential comorbidities and body mass index, suggesting periconceptional diet may be an important social or biological determinant of health underlying existing health disparities.
