In recent years, the widespread use of vitamin D supplementation in pregnant women has been the subject of increasing debate. The available evidence for this practice is summarized, and a guideline for its use is provided. Many of the recent and conflicting studies have not been published in the scientific literature. When the results are compared, however, the overall findings suggest that daily vitamin D supplementation during pregnancy is associated with positive effects on the newborn and mothers, especially when vitamin D doses of at least 1000 IU are administered. The data do not indicate any risks associated with this practice. Supplementation of vitamins and minerals during pregnancy has considerable promise, and the evidence for its benefit is compelling. The guideline is designed to assist practitioners in the development of informed decisions regarding its use.
Vitamin D for Pregnant Women
Vitamin D is one of the important nutrients that play a vital role in bone health, calcium homeostasis, cell growth, and proliferation regulation. What is more, it is now recognized that vitamin D is not just a metabolite of the liver; rather, it has its own physiological actions on various target tissues. In pregnancy, the physiological adaptations to the effects of hypovitaminosis D may result in reduced vitamin D status and elevated parathyroid hormone (PTH). Supplementation in early gestation may be required, especially in those at high risk of gestational diabetes mellitus, preeclampsia, birth defects, chronic hypertension, intrauterine growth restriction, preterm birth, and stillbirth. The same feres to folic acid for pregnancy.
Signs that may indicate a lack of vitamin D levels:
- The fragility of bones – This is affected by a deficiency of calciferol as phosphorus and calcium are not sufficiently absorbed by the body; they are washed out of the bones
muscular hypotension (saggy, full belly);
- Sleep problems;
- Liquid stool;
- The curvature of the skull, spine, and chest;
- Increased neuromuscular excitability (a condition when a person shudders at sharp sounds or flashes of light).
Despite a healthy diet, your body lacks vitamin D during pregnancy; you need to absorb vitamin. But only an obstetrician-gynecologist can prescribe them to a pregnant woman since high doses can also negatively affect a future mom and a baby.
Effect of Vitamin D on Pregnancy
The biological effects of vitamin D are not limited to the modulation of gene expression and, thus, immune function. Many of the effects of vitamin D on the body have been demonstrated to take place through the regulation of processes such as parathyroid hormone (PTH) secretion and, thus, the regulation of calcium and phosphate levels in the blood. The key role of vitamin D in calcium homeostasis in the normal growing child and adult, and the evidence that vitamin D insufficiency is linked to increased risk of chronic disease in the adult population, has led to vitamin D deficiency becoming a focus of attention in public health.
Despite its known adverse effects on pregnancy outcomes, evidence of the benefits of vitamin D supplementation in pregnancy is still controversial. A number of studies have demonstrated that vitamin D supplementation during pregnancy may improve both maternal and neonatal outcomes, including gestational diabetes, pregnancy-induced hypertension and gestational hypertension, and preeclampsia. In addition, there is some evidence that maternal vitamin D supplementation may be associated with a decreased risk of asthma in the offspring. The largest randomized controlled trial, the Vitamin D and Pregnancy Outcome Study conducted in the United Kingdom, has reported that 4,000 iu of vitamin D daily is associated with an increased risk of preeclampsia. However, the trial excluded women who had a prior history of preeclampsia. And so, the findings may not be generalized to women who develop preeclampsia later in pregnancy.
Other trials have not found an association between maternal vitamin D supplementation and improved pregnancy outcomes. However, in all of these trials, the supplementation dosage and dose frequency were only 400 IU of vitamin D daily. Thus, it may be that supplementation at a higher dose may be more beneficial. Similarly, a trial conducted in the Netherlands failed to find any benefit from supplementation with a higher dose of 1000 IU of vitamin D daily. In contrast, a trial conducted by the UK national institute did demonstrate improved maternal outcomes with 800 IU of vitamin D daily. That’s why vitamin D deficient should be avoided.
Dosage of Vitamin D Supplementation During Pregnancy
The optimal dose and the timing of vitamin D supplementation in pregnancy remain controversial. Recent systematic reviews have shown that vitamin D supplementation is associated with a reduced risk of pre-eclampsia and gestational hypertension and improved maternal outcomes, including low birth weight, pregnancy-induced hypertension, and preterm birth. However, the evidence quality is low, which is highlighted by the fact that only half of the trials included in the reviews reported on important outcomes. More importantly, most of the trials, even those that did a report on these outcomes, failed to demonstrate any significant benefit of vitamin D supplementation in pregnancy. While these results need to be interpreted with caution, they do raise the possibility that the potential benefit of prenatal vitamin supplementation may be limited to women with low vitamin D status at the time of supplementation.
The majority of studies from international units that have examined the effect of vitamin D supplementation on maternal and neonatal outcomes have supplemented women during early pregnancy. However, there is increasing interest in addressing vitamin D status in pregnancy. And the literature now includes trials that have supplemented women in late gestation and postpartum. In one study, pregnant women were randomized to receive either no additional calcium (n = 20) or 400 IU of vitamin D daily (n = 21) between 24 weeks’ gestation and delivery. Vitamin D supplementation improved birth weight, with a 466-g mean increase in birth weight in the vitamin D-supplemented group, compared with an increase of 270 g in the control group.
A similar study from college of obstetricians found that mothers receiving 400 IU of vitamin D daily had lower blood pressure and systolic blood pressure than mothers who received no additional calcium during pregnancy. A recent Cochrane review of six trials found that vitamin D supplementation of 600 IU or more daily during pregnancy is associated with a reduction in the risk of gestational hypertension and preeclampsia but not in the risk of preterm delivery or low birth weight.
Pregnant women are especially likely to benefit from folic acid and vitamin D’s role in supporting proper infant development, which is why they should ensure they consume adequate amounts of the vitamin. A high vitamin D intake, especially during pregnancy, may help to keep your baby healthy and developing properly. Check Motherhood Tips for more expert recommendations and future mom tricks.