Researchers studied 40 pregnant women to understand how much vitamin D they ate and how it affected their blood levels and their babies’ blood levels at birth. They found that when pregnant women ate more vitamin D, both they and their babies had higher vitamin D levels in their blood. However, vitamin D intake didn’t seem to strongly affect inflammation markers or iron storage in the blood. This research helps doctors understand the connection between what pregnant women eat and their babies’ health at birth.

The Quick Take

  • What they studied: Whether the amount of vitamin D that pregnant women eat affects vitamin D levels in their blood and their baby’s blood at birth, and whether it affects inflammation and iron levels
  • Who participated: 40 pregnant women from three hospitals in Indonesia who agreed to participate in the study between June and December 2022
  • Key finding: Pregnant women who ate more vitamin D had higher vitamin D levels in their blood, and their babies also had higher vitamin D levels at birth. The connection was moderate and statistically significant, meaning it’s unlikely to be due to chance.
  • What it means for you: Getting enough vitamin D during pregnancy appears to help ensure your baby gets adequate vitamin D at birth. However, this is one small study, and more research is needed before making specific dietary recommendations.

The Research Details

This was a cross-sectional study, which means researchers looked at a group of pregnant women at one point in time rather than following them over months or years. The researchers asked 40 pregnant women about their diet using a food frequency questionnaire—basically a detailed survey about what they typically eat. They then took blood samples from the mothers and from the umbilical cord blood after delivery. These blood samples were tested in a laboratory to measure vitamin D levels, inflammation markers (called interleukin-6), and iron storage (called ferritin). The researchers used statistical tests to see if there were connections between how much vitamin D women ate and their blood levels.

This approach is useful because it shows whether relationships exist between diet and blood levels. However, because it’s a snapshot in time rather than following women over their pregnancy, we can’t be completely sure about cause and effect. The laboratory testing method used (enzyme-linked immunosorbent assay) is a standard, reliable way to measure these substances in blood.

The study was published in Scientific Reports, a reputable journal. The sample size of 40 women is relatively small, which means the results should be viewed as preliminary. All the data followed normal statistical patterns, which is good for the analysis method they used. The study was conducted in real hospital settings with informed consent from participants, which adds credibility.

What the Results Show

The main finding was that vitamin D intake showed a moderate correlation with vitamin D blood levels in both mothers and babies. When mothers ate more vitamin D, their blood vitamin D levels were higher, and their babies’ blood vitamin D levels at birth were also higher. This relationship was statistically significant, meaning it’s unlikely to have happened by chance. The average vitamin D intake was about 16.5 micrograms per day, which is relatively low compared to recommended amounts. Maternal blood vitamin D averaged 14.74 ng/mL and baby blood vitamin D averaged 17.02 ng/mL—both of which are considered low by medical standards (optimal is usually above 30 ng/mL).

The study also looked at inflammation markers and iron storage, but found much weaker connections. Vitamin D intake showed only a weak relationship with inflammation levels in mothers and babies, and this relationship wasn’t statistically significant. There was essentially no meaningful connection between vitamin D intake and iron storage levels in either mothers or babies. This suggests that vitamin D intake primarily affects vitamin D blood levels but may not directly influence these other important pregnancy markers.

Previous research has shown that vitamin D is important for fetal growth and immune system development. This study confirms that maternal diet does affect how much vitamin D reaches the baby, which aligns with what scientists expected. However, the weak relationships with inflammation and iron suggest that vitamin D may work through different pathways than previously thought, or that other factors are more important for controlling these markers during pregnancy.

The study had several important limitations. First, only 40 women participated, which is a small sample size that limits how much we can generalize the findings. Second, it was a snapshot study rather than following women throughout pregnancy, so we can’t determine cause and effect with certainty. Third, the study only measured vitamin D intake through a questionnaire, which relies on women’s memory and may not be perfectly accurate. Fourth, all participants were from Indonesia, so results may not apply to other populations with different diets and sun exposure. Finally, the study didn’t account for other factors that affect vitamin D levels, like sun exposure or supplements.

The Bottom Line

Based on this research, pregnant women should aim to get adequate vitamin D through diet and possibly supplements, as recommended by their healthcare provider. Standard recommendations are typically 600-800 IU daily during pregnancy, though some experts suggest higher amounts. This study suggests that dietary vitamin D does reach the baby, supporting the importance of adequate intake. However, women should consult their doctor about appropriate vitamin D intake for their individual situation.

This research is relevant to pregnant women, women planning pregnancy, and healthcare providers caring for pregnant women. It’s particularly important for women at risk of vitamin D deficiency, including those with limited sun exposure, darker skin tones, or dietary restrictions. The findings are less directly applicable to non-pregnant individuals, though vitamin D remains important for everyone’s health.

Vitamin D levels in blood can change relatively quickly with dietary changes, typically showing measurable differences within weeks to a few months. However, optimal vitamin D status for pregnancy should ideally be established before conception or early in pregnancy, as the baby’s vitamin D status at birth reflects the mother’s status during pregnancy.

Want to Apply This Research?

  • Track daily vitamin D intake in micrograms or IU, including food sources (fatty fish, fortified milk, egg yolks) and any supplements. Set a daily goal based on your healthcare provider’s recommendation and log actual intake to identify gaps.
  • Add one vitamin D-rich food to your daily diet, such as a serving of salmon, fortified milk, or an egg. If dietary sources are insufficient, discuss vitamin D supplementation with your healthcare provider and set a reminder to take it consistently.
  • Monitor vitamin D intake weekly and note any dietary patterns. If possible, work with your healthcare provider to check blood vitamin D levels periodically during pregnancy to ensure adequate status. Track any related symptoms like fatigue or bone discomfort that might indicate deficiency.

This research is preliminary and based on a small study of 40 women in Indonesia. It should not replace personalized medical advice from your healthcare provider. Pregnant women should consult their doctor or midwife before making changes to their diet or starting supplements, as individual needs vary based on health status, location, skin tone, and other factors. This study shows correlation, not definitive cause and effect. Always follow your healthcare provider’s recommendations for vitamin D intake during pregnancy.