Popping a prenatal vitamin? Double-check that it contains vitamin D, because taking vitamin D during pregnancy could lower your baby’s risk for eczema through their first year, according to a recent study.
The report was published in the "British Journal of Dermatology."
The researchers examined data from more than 700 pregnant women. Of them, 352 took 1,000 international units (IU) of vitamin D from 14 weeks until they gave birth and 351 took a placebo.
Researchers found that babies born to mothers who took vitamin D daily from 14 weeks until delivery had a lower risk for atopic eczema. The result was particularly seen in babies who were later breastfed for more than a month (but not in those who breastfed for less than a month).
Atopic eczema (or atopic dermatitis) is chronic. About 13% of American children have the condition, the National Eczema Association reports. Eczema symptoms can include redness and rash, itching, dry and scaly skin, or open and crusty sores. About 50% of children with moderate to severe cases later develop allergic asthma. Eczema has been linked to food allergies.
Evaluating the effects of vitamin D and eczema
The study was the first randomized controlled trial (considered the gold standard of clinical trials) to show evidence that mothers may be able to reduce the risk of atopic eczema in infants by taking vitamin D while pregnant.
"Our aim was to see whether taking 1,000 IU of vitamin D (cholecalciferol) as a supplement during pregnancy would decrease the risk of atopic eczema in babies. We also wanted to establish whether breastfeeding had any effect on this,” Sarah El-Heis, first author of the paper, said in a statement.
"Our results showed that babies of mothers who received supplements had a lower chance of having atopic eczema at 12 months, which supports recommendations for vitamin D supplements to be routine during pregnancy,” she notes.
At 1 year old, 7.2% of children had eczema of mothers who took the supplement—but it was 12% in those who didn’t.
El-Heis says they didn’t find an effect at 24 and 48 months. This indicates that “other postnatal influences might become more important beyond infancy or that the babies themselves might also need to be supplemented during the postnatal period for a sustained effect,” she said in a statement.
“Interestingly, the preventive effect was particularly seen in babies who were later breastfed for more than a month,” Keith Godfrey, another researcher on the team, tells Motherly, via email. “This suggests that the pregnancy supplement may act by increasing the amounts of vitamin D in breast milk. The research provides yet more evidence of the benefits of measures to support mothers in breastfeeding their infants.”
(Remember, breast milk isn’t the only way for your bundle of joy to get vitamin D, which is naturally low in breast milk. Ask your pediatrician if your baby needs to supplement.)
“There is now an evidence-based global consensus that supplements containing multiple vitamins and minerals have greater benefits during pregnancy than the usual iron and folic acid supplements recommended by many practitioners,” Godfrey adds.
Supplementing individual vitamins is often needed in specific circumstances, but a high proportion of women in Europe and North America may have insufficient levels, especially during winter and early spring, he says. So if you’re pregnant, especially, it’s important to make sure you’re getting enough vitamin D.
How much vitamin D do you need in pregnancy?
If you start taking vitamin D early enough in pregnancy, ideally before conception, then the standard recommendation of 400 IU “may perhaps be sufficient,” Godfrey says. “We need more evidence on this.”
That said, pregnant women should certainly be making sure that their prenatal vitamins contain vitamin D, he adds.
If your doc says you don’t have enough vitamin D, most experts agree that 1,000 to 2,000 IU per day is safe, The American College of Obstetrics and Gynecology reported in 2011. They say all women, pregnant or not, need 600 IU of vitamin D a day.
Regular prenatal vitamins typically contain 400 IU of vitamin D; 600 IUs are actually recommended in pregnancy, says Lauren Demosthenes, MD, the senior medical director at virtual care provider Babyscripts.
Can vitamins do it all?
The study came just weeks after new recommendations from the United States Preventive Services Task Force (USPSTF) say there was “insufficient evidence" that multivitamins and supplements can prevent cardiovascular disease and cancer in healthy, non-pregnant adults.
Don’t be confused, writes Natalie Cameron, an instructor of general internal medicine at Northwestern University Feinberg School of Medicine, in a June 2022 editorial in JAMA. "Pregnant individuals should keep in mind that these guidelines don't apply to them," she says.
Many American women aren’t in the best of shape heart-wise before they get pregnant. Talking to your doctor about vitamin supplementation and improving heart health before conceiving can be an important part of prenatal care to discuss with your doctor.
The bottom line
To sum it up: vitamin D during pregnancy is important. (And recent research shows that it has other health benefits even if you’re not expecting).
Pregnant or not, if you pop a multivitamin thinking it can stave off cancer or cardiovascular issues, don’t rely on the supplement to save you. Incorporate other interventions, like nutrition and exercise, which may be able to work more powerfully.
“After reading this article, I would err on the side of taking the extra 1000 IUs of vitamin D and I would breastfeed for over one month. I see potential good and no harm,” Dr. Demosthenes tells Motherly.
Lauren Demosthenes, MD, the senior medical director at virtual care provider Babyscripts.
Keith Godfrey MBE, BM PhD FRCP MAE FMedSci leads the NIHR Southampton Biomedical Research Centre Lifecourse Nutrition, Lifestyle and Health Theme, is an NIHR Senior Investigator and Professor of Epidemiology & Human Development at the MRC Lifecourse Epidemiology Centre at the University of Southampton.
El-Heis S, et al. Maternal antenatal vitamin D supplementation and offspring risk of atopic eczema in the first 4 years of life: evidence from a randomized controlled trial. British Journal of Dermatology. 2022. doi:10.1111/bjd.21721
Jia J, et al. Multivitamins and supplements—benign prevention or potentially harmful distraction? JAMA. 2022. doi:10.1001/jama.2022.9167