Effects of Maternal Vitamin D Supplementation on Childhood Health

Abstract

Vitamin D deficiency during pregnancy is associated with an increased risk of health issues in the offspring. Accordingly, recent Endocrine Society guidelines strongly support supplementation in pregnancy, also underlining that without consensus on optimal maternal vitamin D levels, routine screening is currently irrelevant. Knowledge of organ-specific effects of vitamin D and its association with maternal vitamin D status may aid in optimizing vitamin D supplementation. This systematic review outlines the proposed next-generation effects of vitamin D supplementation ≥400 IU/d and explores whether such effects are attributed to a specific maternal vitamin D level obtained during pregnancy. A systematic literature search was conducted in PubMed and Embase according to the PRISMA guidelines, focusing on health outcomes from 10 days postpartum and beyond. Of the 2383 screened articles, 38 were included. In 11 of 16 studies, vitamin D supplementation reduced respiratory tract infections in the first years of life. Growth or bone development benefits were observed in 6 of 12 studies. Positive effects on neurodevelopment and reduced autoimmune risk (diabetes-related antibodies) were noted, although further research is needed to determine the role of vitamin D. Very few studies have measured vitamin D concentrations, but even 1600 IU/d supplementation was associated with high frequency of infant vitamin D insufficiency. Current recommendations may not ensure sufficient vitamin D levels at birth, among others, increasing the risk of early-life infections. Further studies linking maternal and infant vitamin D levels to specific outcomes would aid in personalized nutritional advice during pregnancy and improve next-generation health.

Keywords: development of children; intrauterine vitamin D exposure; vitamin D deficiency; vitamin D supplementation in pregnancy.

Graphical Abstract

Figure 1.

Overview of the recommended dose of vitamin D supplementation in pregnancy in selected countries (7, 27-33). The zenith angle of 33° latitude during August and March is illustrated in the northern hemisphere (top two horizontal lines) and southern hemisphere (bottom two horizontal lines), as a zenith angle below 33° inhibits cutaneous vitamin D production (7, 21).

Figure 2.

PRISMA diagram of the screening process.

Figure 3.

The 38 included studies were divided into 8 different outcomes. Where n indicates the number of participants, followed by the quality assessment score, either the JADAD score (J) or NOS score (N). *Indicates studies with significant findings. The number in parentheses represents the reference number.

Figure 4.

The included studies according to country of origin, study type, and dose of vitamin D supplement. Significant outcomes are marked by asterisks.

Figure 5.

Dosage of vitD in the 31 different RCT studies in this review divided into having an effect or not on the children's different outcome.

Figure 6.

Follow-up time of each study, displayed by the target organ. The stars indicate the presence of a statistically significant effect of vitD exposure. Overall, 22 studies (22, 90, 91, 93-96, 98, 103, 104, 106-112, 118-120, 122, 123) reported a beneficial effect of vitD, whereas 17 studies (27, 28, 92, 97, 99-102, 105, 113-117, 121, 124) found no association between vitD exposure and health outcomes of the exposed children.

Figure 7.

VitD associations with growth, separated according to dose and follow-up time (98, 101, 108, 111, 114). *Indicate significant results of vitD supplementation.