(RxWiki News) One recent study found that too little vitamin D didn't appear to affect baby's bone growth. But there are other risks if expecting moms have too little vitamin D.
Researchers recently reviewed past studies on vitamin D levels during pregnancy. The researchers found that a vitamin D deficiency increased pregnant women's risks of several pregnancy complications.
These complications included gestational diabetes, pre-eclampsia and giving birth to an underweight baby.
Vitamin D can be gained through supplements and through natural exposure to sunlight.
"Attend all prenatal visits."
The study was led by Fariba Aghajafari, an assistant professor of family medicine at the Department of Community Health Sciences at the University of Calgary in Canada.
The researchers reviewed five large medical databases of studies and trials going back to 1966. They only looked for studies that investigated links between pregnant women's blood levels of vitamin D and a number of pregnancy complications.
The pregnancy complications the researchers looked for included gestational diabetes, pre-eclampsia, bacterial vaginosis, cesarean section, small-for-gestational-age babies, birth weight of babies, length of newborns and newborns' head circumference.
Gestational diabetes occurs when a pregnant woman who did not previously have diabetes develops the inability to adequately regulate the hormone insulin.
Pre-eclampsia occurs when a pregnant woman develops high blood pressure and protein in her urine. The only cure is to deliver the baby.
Bacterial vaginosis is an infection of the vagina caused by bacteria. A baby is small for gestational age if the child is underweight given the week of pregnancy when it was born. This measurement is different than having low birth weight.
Overall, the researchers identified 3,357 studies that dealt with vitamin D and these outcomes, but only 31 were determined to be of appropriate quality to include in the final analysis.
The researchers analyzed the data from all the studies together and found that insufficient levels of vitamin D were linked to several poor pregnancy outcomes.
Women with deficient vitamin D levels were 49 percent more likely to develop gestational diabetes, 79 percent more likely to develop pre-eclampsia and 85 percent more likely to have a baby who was small for the week of pregnancy when the baby was born.
Women with low vitamin D levels were also at risk for bacterial vaginosis and having a baby with a low birth weight. These women were not at a higher risk for C-section.
These findings do not mean that being deficient in vitamin D caused these outcomes. It is possible that women who do not have enough vitamin D have poor diets or lifestyles or other factors preventing them from getting necessary vitamins and minerals in general for their bodies and developing babies.
Pregnant women should not take any dietary supplements without first discussing the risks and benefits of doing so with her doctor.
The study was published March 26 in the journal BMJ. The research was funded by the University of Calgary Institute for Public Health, Alberta Innovate Health Solutions, the Canadian Institute of Health Research and the Canadian Foundation for Healthcare Improvement. The authors declared no conflicts of interest.