According to Gram Research analysis, a 2026 cross-sectional study of 396 pregnant women in Jordan found that 99.7% had dangerously low vitamin D levels (below 20 ng/mL), and their newborns had similarly low levels at birth. Only 19% of the women took vitamin D supplements during pregnancy, and babies born smaller than expected had even lower vitamin D than normal-sized babies, suggesting a possible link between maternal vitamin D deficiency and restricted fetal growth.
A new study of nearly 400 pregnant women in Jordan found that almost all of them had vitamin D levels that were too low. Researchers measured vitamin D in the mothers’ blood and in their newborns’ umbilical cord blood right after birth. They discovered that 99.7% of the mothers and 99.5% of the babies had vitamin D levels below what’s considered healthy. The study also found that babies born smaller than expected had even lower vitamin D levels than other babies. This research suggests that vitamin D deficiency during pregnancy is a major health concern that needs attention.
Key Statistics
A 2026 cross-sectional study of 396 pregnant women in Jordan found that 99.7% had vitamin D levels below 20 ng/mL (deficient), with a median level of just 9.86 ng/mL at delivery.
In the same study of 396 Jordanian mothers and newborns, 99.5% of cord blood samples showed vitamin D deficiency, with newborns having a median level of 10.12 ng/mL.
Only 19.1% of 396 pregnant women in a 2026 Jordanian study reported taking vitamin D supplements, averaging just 1,053 international units daily—below recommended prenatal amounts.
A 2026 study of 396 pregnancies in Jordan found that babies born small for gestational age had significantly lower vitamin D levels (9.3 ng/mL) compared to normal-sized babies (10.19 ng/mL).
The Quick Take
- What they studied: Whether pregnant women and newborns in Jordan have enough vitamin D in their blood, and whether low vitamin D is connected to pregnancy problems and baby health issues.
- Who participated: 396 pregnant women who gave birth at King Abdullah University Hospital in Jordan between November 2021 and July 2022, plus their newborns.
- Key finding: Nearly all the pregnant women (99.7%) and almost all the newborns (99.5%) had vitamin D levels below 20 ng/mL, which is considered deficient. Only 19% of the women took vitamin D supplements during pregnancy.
- What it means for you: If you’re pregnant or planning to become pregnant, especially in regions with limited sun exposure, vitamin D testing and supplementation may be important. Talk to your doctor about whether you need vitamin D supplements, as this study shows deficiency is extremely common in some populations.
The Research Details
This was a cross-sectional study, which means researchers took a snapshot of vitamin D levels at one point in time (at delivery) rather than following women over months. The team collected blood samples from 396 pregnant women and their newborns at King Abdullah University Hospital in Jordan between November 2021 and July 2022. They measured vitamin D using a lab test called ELISA, which detects the specific form of vitamin D in the blood (25-hydroxyvitamin D). The researchers then looked for patterns—did mothers with low vitamin D have babies with low vitamin D? Did low vitamin D connect to smaller babies or other problems?
Cross-sectional studies are useful for identifying how common a problem is and spotting connections between factors, but they can’t prove that one thing causes another. This study is important because it shows how widespread vitamin D deficiency is in a specific population, which helps doctors understand who might need screening and treatment. The findings can guide public health decisions about whether vitamin D supplementation should be recommended during pregnancy.
The study included a reasonably large sample (396 women), used a standard lab test to measure vitamin D, and performed appropriate statistical analysis. However, because it’s a cross-sectional study, it can only show associations, not cause-and-effect relationships. The study was conducted in one hospital in Jordan, so results may not apply to all populations. The researchers did not report information about all factors that might affect vitamin D levels, such as sun exposure or dietary intake beyond supplements.
What the Results Show
The results were striking: the median vitamin D level in mothers was 9.86 ng/mL and in newborns was 10.12 ng/mL. To put this in perspective, health experts generally consider levels below 20 ng/mL as deficient (not enough), and levels between 20-29 ng/mL as insufficient (borderline low). This means 99.7% of mothers and 99.5% of newborns fell into the deficient category. Only 76 women (19.1%) reported taking vitamin D supplements during pregnancy, and those who did took an average of about 1,053 international units per day—which is below the recommended amount for pregnant women. The vitamin D levels in mothers and newborns were positively correlated, meaning mothers with higher vitamin D tended to have babies with higher vitamin D, though the connection was moderate.
The study found that vitamin D levels were lower in babies born small for their gestational age (smaller than expected for how far along the pregnancy was) compared to babies of normal size. Specifically, small babies had a median vitamin D level of 9.3 ng/mL versus 10.19 ng/mL in normal-sized babies. This difference was statistically significant, suggesting a possible link between low maternal vitamin D and restricted fetal growth. The researchers also noted that maternal age, body mass index, and season of delivery were associated with vitamin D levels, though the details of these associations were not fully described in the abstract.
This study adds to growing evidence that vitamin D deficiency during pregnancy is common in certain regions and may be linked to pregnancy complications. Previous research has suggested connections between low vitamin D and problems like gestational diabetes, preeclampsia, and restricted fetal growth. This Jordanian study supports those concerns and highlights that the problem is particularly severe in this population, where nearly universal deficiency was found. The findings align with other research showing that vitamin D status at birth reflects maternal vitamin D status and that supplementation during pregnancy is often inadequate.
This study has several important limitations. First, it’s a snapshot at one moment (delivery), so researchers couldn’t track how vitamin D levels changed during pregnancy or identify when deficiency developed. Second, the study was conducted at a single hospital in Jordan, so results may not apply to other regions or populations with different sun exposure, diet, or genetics. Third, the researchers didn’t collect detailed information about factors affecting vitamin D, such as how much sun exposure women had, their dietary sources of vitamin D, or their skin tone (which affects vitamin D production from sunlight). Fourth, because this is a cross-sectional study, it can show that low vitamin D is associated with smaller babies, but it cannot prove that low vitamin D causes babies to be smaller—other factors could be involved.
The Bottom Line
Based on this research, pregnant women—particularly those in regions with limited sun exposure like Jordan—should discuss vitamin D screening and supplementation with their healthcare provider. Current recommendations suggest pregnant women get 600-800 international units of vitamin D daily, though some experts recommend higher amounts. The study suggests that current supplementation practices are inadequate in this population. Women should not start supplements without medical guidance, but this research supports the importance of vitamin D assessment during pregnancy.
This research is most relevant to pregnant women and women planning pregnancy, especially those living in regions with limited sunlight or with cultural practices that limit sun exposure. Healthcare providers in these regions should consider vitamin D screening as part of prenatal care. The findings are also important for public health officials considering population-wide recommendations. Women with darker skin tones, those who cover their skin for cultural or religious reasons, and those with limited access to vitamin D-rich foods should be particularly attentive to vitamin D status.
Vitamin D supplementation during pregnancy needs to be started early and continued throughout pregnancy to be effective. If you’re planning to become pregnant, discussing vitamin D with your doctor several months before conception is ideal. If you’re already pregnant, it’s never too late to start supplementation, though earlier is better. You won’t notice immediate changes, but adequate vitamin D during pregnancy supports fetal development throughout the nine months.
Frequently Asked Questions
What vitamin D level should pregnant women have?
Health experts consider vitamin D levels of 20 ng/mL or higher as adequate, 20-29 ng/mL as insufficient, and below 20 ng/mL as deficient. A 2026 study found 99.7% of pregnant women in Jordan fell below 20 ng/mL, indicating widespread deficiency in that population.
Can low vitamin D during pregnancy affect the baby?
Research suggests possible connections between maternal vitamin D deficiency and smaller babies at birth. A 2026 study of 396 pregnancies found babies born small for gestational age had lower vitamin D levels than normal-sized babies, though more research is needed to confirm cause-and-effect.
How much vitamin D should I take while pregnant?
Current recommendations suggest 600-800 international units daily for pregnant women, though some experts recommend higher amounts. A 2026 study found pregnant women in Jordan averaged only 1,053 units daily when supplementing, suggesting many need more. Consult your doctor for personalized recommendations.
Does vitamin D pass from mother to baby?
Yes. A 2026 study of 396 pregnancies found moderate correlation between maternal and newborn vitamin D levels, meaning mothers with higher vitamin D tended to have babies with higher vitamin D. This shows the baby’s vitamin D status depends partly on the mother’s.
Who is most at risk for vitamin D deficiency during pregnancy?
Women with limited sun exposure, those who cover their skin for cultural or religious reasons, those with darker skin tones, and those with limited access to vitamin D-rich foods face higher risk. A 2026 study found nearly universal deficiency in Jordan, suggesting geographic and lifestyle factors play major roles.
Want to Apply This Research?
- Track your vitamin D supplementation daily (dose and time taken) and note any prenatal vitamin D lab results. Set a reminder for your vitamin D supplement at the same time each day to ensure consistency.
- If your doctor recommends vitamin D supplementation, add it to your daily routine by taking it with breakfast or another regular meal. If you’re not currently taking prenatal vitamins with vitamin D, discuss with your healthcare provider whether you should start. In sunny climates, aim for 10-30 minutes of midday sun exposure several times per week (without sunscreen) to support natural vitamin D production.
- Request vitamin D testing at your first prenatal visit and again in the third trimester to track your levels. Log your supplement intake in the app and note any prenatal appointments where vitamin D was discussed. Share your supplementation data with your healthcare provider at each visit to ensure you’re meeting recommended intake levels.
This research describes vitamin D levels in a specific population in Jordan and associations between vitamin D and birth outcomes. It does not prove that vitamin D deficiency causes pregnancy complications. Pregnant women should not start, stop, or change vitamin D supplementation without consulting their healthcare provider. This article is for educational purposes and should not replace professional medical advice. If you are pregnant or planning pregnancy, discuss vitamin D screening and supplementation with your doctor based on your individual health status and risk factors.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.