Prenatal diets that meet U.S. dietary guidelines reduce the risk for slow or rapid infant growth, but the association between infant growth and low-inflammation diets is unclear, according to findings published in JAMA Network Open.

"Both slow and rapid weight gain during the first year of life are associated with later life obesity risk," Monique M. Hedderson, PhD, a research scientist at the Kaiser Permanente Northern California Division of Research, and colleagues wrote. "However, most previous studies on prenatal diet examined birth weight and lacked information on infant growth."

The prospective study included 2,854 birthing parent-child pairs (51.3% boy infants; median maternal age, 30 years; interquartile range, 25 to 34 years) who participated in the Environmental influences on Child Health Outcomes (ECHO) program between 2007 and 2021. The researchers investigated links between mothers' prenatal diet quality and infant growth up to 24 months after birth. They rated mothers' diets using the 2015 Healthy Eating Index (HEI), in which a score higher than 80 indicates a healthy diet; and the Empirical Dietary Inflammatory Pattern (EDIP), in which scores of 63.6 or lower indicate a high-quality diet.

Overall, 303 women (10.6%) had an HEI score above 80, and 205 women had EDIP scores of 63.6 or lower. At ages 6, 12 and 24 months, 30%, 39% and 23% of infants had rapid growth, and 15%, 9% and 7.5% had slow growth, respectively.

Babies born to women with higher HEI scores were less likely to be large for gestational age at birth (adjusted OR = 0.88; 95% CI, 0.79-0.98) compared with those born to parents with lower HEI scores. They were also less likely to experience rapid growth from birth to age 6 months (aOR = 0.8; 95% CI, 0.37-0.94) and 24 months (aOR = 0.82; 95% CI, 0.7-0.96), or slow growth from birth to age 6 months (aOR = 0.65; 95% CI, 0.51-0.84), 12 months (aOR = 0.74; 95% CI, 0.65-0.83) or 24 months (aOR = 0.65; 95% CI, 0.56-0.76).

Associations with high- and low-inflammatory diets were less consistent, Hedderson and colleagues noted. Compared with babies born to women with high-inflammation diets, those born to women with low EDIP scores were more likely to be large for gestational age (aOR = 1.24; 95% CI, 1.13-1.36). Low-inflammatory diets were also associated with lower odds for rapid growth between birth and age 6 months. However, Hedderson and colleagues reported that low EDIP scores were associated with higher odds for slow growth from birth to age 24 months (aOR = 1.5; 95% CI, 1.18-1.91).

Neither diet was significantly associated with babies being born small for gestational age, Hedderson and colleagues wrote.

"These findings support a prenatal diet that aligns with U.S. Dietary Guidelines (as measured by the HEI) to promote healthy birth weight and infant growth through age 24 months," the authors wrote. "More studies are needed to understand the potential benefits or harms of low-inflammatory prenatal dietary patterns in fetal and infant growth."