Research led by investigators from the University of Pittsburgh Graduate School of Public Health suggests that women who have a vitamin D deficiency in the first 26 weeks of pregnancy are more likely to develop severe preeclampsia. This is according to a study recently published in the journal Epidemiology.

Preeclampsia is a potentially life-threatening pregnancy complication that usually occurs after the first 20 weeks of gestation or shortly after birth. According to the Preeclampsia Foundation, around 5-8% of pregnancies are affected by the condition.

Early signs of the condition include high blood pressure and albuminuria – excess protein that leaks into the urine.

Some women may also experience swelling of the feet, ankles, face and hands – caused by fluid retention – as well as severe headaches, problems with vision and pain just below the ribs.

Vitamin D is known to be important for regulating and absorbing calcium and phosphorus in the body.

The majority of people are able to get all the vitamin D they need from the sun and various foods, such as oily fish, eggs and fortified fat spreads.

However, according to the Vitamin D Council, pregnancy is a known risk factor for vitamin D deficiency.

Previous research has suggested that vitamin D deficiency during pregnancy may lead to gestational diabetes, increased risk of infections and cesarean section, and low offspring birth weight.

To determine whether there is an association between vitamin D deficiency during pregnancy and risk of preeclampsia, the research team analyzed the blood samples of 700 pregnant women who later developed preeclampsia, alongside the blood samples of 3,000 pregnant women who did not develop the condition.

All samples were collected between 1959 and 1965 from 12 US institutions. The researchers note that the blood samples were well-preserved and they were able to test the samples for vitamin D levels decades after they were collected.

The analysis revealed that women who had insufficient levels of vitamin D during the first 26 weeks of pregnancy were 40% more likely to develop severe preeclampsia, compared with women who had adequate levels of the vitamin in the first 26 weeks’ gestation.

However, the researchers did not find any association between vitamin D and mild preeclampsia.

These results were apparent after taking other factors into consideration that could impact a woman’s vitamin D levels, such as pre-pregnancy body mass index (BMI), race, smoking, diet, the number of previous pregnancies, physical activity and sunlight exposure.

Commenting on the findings, senior study author Dr. Mark A. Klebanoff, of the Center for Perinatal Research at The Research Institute at Nationwide Children’s Hospital and the Department of Pediatrics at The Ohio State University College of Medicine, says:

Scientists believe that severe preeclampsia and mild preeclampsia have different root causes.

Severe preeclampsia poses much higher health risks to the mother and child, so linking it with a factor that we can easily treat, like vitamin D deficiency, holds great potential.”

Dr. Lisa Bodner, of the Department of Epidemiology at the University of Pittsburgh Graduate School of Public Health and lead author of the study, says that if similar results are found in a modern sample of pregnant women, then the role of vitamin D in reducing preeclampsia should be explored further.

“Until then,” she adds, “women shouldn’t automatically take vitamin D supplements during pregnancy as a result of these findings.”

Medical News today recently reported on a study suggesting that mothers who have a higher vitamin D intake during pregnancy are more likely to have children with stronger muscles.