Nonlinear and Sex-Specific Associations of Maternal Vitamin D in Early- and Mid-Pregnancy with Childhood Growth Trajectories From Birth to 6 Years of Age: A Prospective Cohort Study in China

Why It Matters

The findings underscore the need for precise vitamin D monitoring during pregnancy to curb unstable childhood growth patterns and future obesity risk, informing more nuanced prenatal nutrition guidelines.

Key Takeaways

• Both deficient and excess maternal vitamin D link to unstable child growth
• Optimal maternal 25OHD: ~30‑75 nmol/L for favorable trajectories
• Boys more sensitive to high early‑pregnancy vitamin D for BMI gain
• Low mid‑pregnancy vitamin D raises risk of increasing weight and height Z‑scores
• Increasing BMI trajectories lead to ten‑fold higher overweight prevalence at age 6

Pulse Analysis

Vitamin D deficiency remains a global public‑health concern, affecting nearly half of all adults and an even larger share of pregnant women. While its role in calcium homeostasis is well established, emerging research points to broader developmental effects, particularly on fetal programming and post‑natal growth. Prior studies have typically examined a single gestational window or relied on cross‑sectional data, leaving a gap in understanding how maternal vitamin D dynamics across pregnancy influence long‑term child growth patterns.

The Wuxi Birth Cohort addressed this gap by tracking 1,100 mother‑child dyads with serum 25‑hydroxyvitamin D measured in early and mid‑pregnancy and detailed anthropometry collected through age six. Using group‑based trajectory modeling, researchers identified distinct weight, height and BMI trajectories and linked them to maternal vitamin D tertiles. Results revealed a U‑shaped risk curve: both low and high maternal vitamin D levels were associated with unstable growth trajectories, with the safest window around 30‑75 nmol/L. Notably, boys exhibited a stronger response to elevated early‑pregnancy vitamin D in terms of BMI acceleration, while girls showed greater sensitivity of linear growth to low mid‑pregnancy levels.

These insights have practical implications for obstetric care. Rather than a one‑size‑fits‑all supplementation strategy, clinicians may need to tailor vitamin D dosing to maintain maternal concentrations within the identified optimal range, accounting for seasonal variation and baseline status. Public‑health policies could incorporate routine vitamin D screening in prenatal visits and provide guidance on safe supplementation limits. Future research should explore the biological mechanisms behind the sex‑specific responses and assess whether similar patterns hold in diverse populations, ultimately guiding evidence‑based recommendations to promote healthy growth trajectories from the womb onward.