Maternal Fat-Soluble Vitamin Trajectories and Birth Weight in Overweight/Obese Pregnancy

Overview

In pregnant individuals with overweight or obesity, maternal vitamin A and D levels declined from the second to third trimester, while vitamin E increased. Despite common vitamin insufficiencies and a high rate of macrosomia, maternal fat-soluble vitamin concentrations were not independently associated with birth weight.

Background

Birth weight is a critical determinant of long-term cardiometabolic health, with both low birth weight and macrosomia linked to increased risk of obesity, diabetes, and cardiovascular disease. Fat-soluble vitamins A, D, and E play roles in fetal growth through effects on cellular differentiation, hormone signaling, and oxidative balance. However, the impact of maternal vitamin status on birth weight, especially in pregnancies complicated by overweight or obesity, remains unclear due to altered vitamin metabolism in this population.

Data Highlights

Vitamin insufficiency/deficiency prevalence in 3rd trimester: Vitamin A insufficiency 19.3%, Vitamin D deficiency 31.6%, Vitamin D insufficiency 33.3%. Macrosomia occurred in 43.9% of infants.

Key Findings

• Maternal retinol and 25(OH)D concentrations significantly decreased from the second to third trimester.
• Maternal α-tocopherol concentrations significantly increased across the same period.
• Vitamin A insufficiency and vitamin D deficiency/insufficiency were common in the third trimester among overweight/obese pregnant individuals.
• Macrosomia was frequent, affecting nearly 44% of infants in this cohort.
• No independent associations were found between maternal vitamins A, D, or E concentrations and birth weight.
• No interaction effect between vitamins A and D on birth weight was observed.

Clinical Implications

Monitoring fat-soluble vitamin status in pregnant individuals with overweight or obesity is important given the high prevalence of insufficiencies and deficiency. However, maternal vitamin A, D, and E levels during mid-to-late pregnancy may not be major determinants of fetal growth or macrosomia risk in this population. Clinicians should consider multifactorial influences on birth weight beyond vitamin status when managing pregnancies complicated by overweight or obesity.

Conclusion

Maternal fat-soluble vitamin concentrations change during pregnancy in overweight or obese individuals, with common insufficiencies and a high incidence of macrosomia. Despite these observations, vitamin A, D, and E levels were not independently linked to birth weight, suggesting other factors predominantly influence fetal growth in this high-risk group.

References

1. ETIP Study Group 2010-2015 -- Exercise Training in Pregnancy Trial