To examine differences in prenatal diet quality by socio-economic status (SES) and race/ethnicity.

A secondary, cross-sectional analysis. Race and SES were self-reported prenatally; SES was categorized into four groups: high-income, middle-income and low-income WIC (Special Supplemental Nutrition Program for Women, Infants, and Children) participant/non-participant. The Alternative Healthy Eating Index for Pregnancy (AHEI-P) measured diet quality, including four moderation and nine adequacy components (higher scores = healthier diet). Generalized linear models adjusted for covariates and post hoc testing with Tukey adjustment compared AHEI-P scores between groups, using a threshold of P < 0·05.

Infant Feeding Practices Study II, conducted in a national US convenience cohort.

Women in their third trimester (n 1322) with dietary history.

Participants were of 28·9 (se 5·6) years on average and predominantly non-Hispanic White (84 %); approximately one-third participated in WIC and 17 % were high-income. The mean AHEI-P score was 61·7 (se 10·8) of 130 points. High-income women had higher total (62·4 (se 1·0)) and moderation component AHEI-P scores than middle-income (60·1 (se 0·8), P = 0·02), low-income WIC participants (58·3 (se 0·8), P < 0·0001) and non-participants (58·9 (se 0·9), P = 0·001). Non-Hispanic Black participants had lower total (57·8 (se 1·4)) and adequacy scores than Other races (i.e. neither non-Hispanic Black nor White, 62·1 (se 0·9), P = 0·02).

Disparities in prenatal diet quality were observed, with non-Hispanic Black women, low-/middle-income and WIC participants having lower diet quality. However, interventions are needed to improve prenatal diet quality broadly among US women.

Dietary quality (DQ), as assessed by the Alternative Healthy Eating Index for Pregnancy (AHEI-P), and conception and pregnancy outcomes were evaluated.

In this prospective cohort study on couples planning their first pregnancy. Cox proportional hazards regression assessed the relationship between AHEI-P score and clinical pregnancy, live birth and pregnancy loss.

Participants were recruited from the Northeast region of the USA.

Participants: Healthy, nulliparous couples (females, n 132; males, n 131; one male did not enrol).

There were eighty clinical pregnancies, of which sixty-nine resulted in live births and eleven were pregnancy losses. Mean (sd) female AHEI-P was 71·0 (13·7). Of those who achieved pregnancy, those in the highest tertile of AHEI-P had the greatest proportion of clinical pregnancies; however, this association was not statistically significant (P = 0·41). When the time it took to conceive was considered, females with the highest AHEI-P scores were 20 % and 14 % more likely to achieve clinical pregnancy (model 1: hazard ratio (HR) = 1·20; 95 % CI 0·66, 2·17) and live birth (model 1: HR = 1·14; 95 % CI 0·59, 2·20), respectively. Likelihood of achieving clinical pregnancy and live birth increased when the fully adjusted model, including male AHEI-P score, was examined (clinical pregnancy model 4: HR = 1·55; 95 % CI 0·71, 3·39; live birth model 4: HR = 1·36; 95 % CI 0·59, 3·13).

The present study is the first to examine AHEI-P score and achievement of clinical pregnancy. DQ was not significantly related to pregnancy outcomes, even after adjustments for covariates.