The Planetary Health Diet (PHD), proposed by the EAT–Lancet Commission, seeks to optimize health while preserving the environment. Its benefits for chronic disease prevention are established, but impacts on birth outcomes are unclear. To assess the association between PHD adherence during pregnancy and newborn outcomes. This prospective study included 1,431 mother-infant dyads from the New Hampshire Birth Cohort Study. Diet during pregnancy was assessed once at 24–28 weeks’ gestation via a food-frequency questionnaire to calculate the Planetary Health Diet Index (PHDI). Gestational age, birth weight, length, and head circumference were abstracted from medical records. Dietary patterns were identified through Self-Organizing Maps using PHDI components. Associations between PHD and birth outcomes were modeled using multivariable regressions. Highest PHDI tertile participants were older, had lower pre-pregnancy body mass index, were more often nonsmokers, and had higher neighborhood socioeconomic status. In adjusted regression models, 10-unit increase in PHDI was associated with higher birth weight (β = 24.4 g 95% Confidence Interval (CI): 1.21, 43.6, longer gestation (β = 0.10 weeks; 95% CI: 0.03, 0.17) and reduced odds of being preterm Odds Ratio (OR) = 0.86; 95% CI: 0.74, 0.98. Three distinct dietary patterns were identified: plant-based, saturated fat–rich, and animal/added sugar–rich. Compared to the plant-based profile, the saturated fat–rich profile was associated with shorter gestation and higher odds of low birth weight (OR = 2.54; 95% CI: 1.23, 5.44). The animal/added sugar–rich profile correlated with lower birth weight (β = –82.4 g; 95% CI: –149.2, –15.6) and shorter length (β = –0.46 cm; 95% CI: –0.84, –0.08). Both non–plant-based profiles increased the odds of preterm birth (OR = 1.92 and OR = 1.66, respectively). Originally proposed for chronic disease prevention and planetary sustainability, higher adherence to the PHD during pregnancy may also benefit birth outcomes, particularly lower odds of preterm birth.
Barandiaran et al. (Sun,) studied this question.