Could low vitamin D levels lead to preeclampsia? Some researchers say yes.
A study done by the University of Pittsburgh Schools of the Health Sciences found that vitamin D deficiency early in pregnancy is associated with a five-fold increased risk of preeclampsia. Preeclampsia, also known as toxemia, is a common complication of pregnancy. Many of the women included in the study reported taking prenatal vitamins, which typically contain 200 to 400 International units (IU) of vitamin D, which alarmed researchers.
What is Preeclampsia?
Preeclampsia is marked by high blood pressure along with a high level of protein in the urine. The hands, feet, and legs of women with preeclampsia often swell up. It occurs during the latter part of the second half of pregnancy, or in the third trimester. If left untreated there is a risk for eclampsia and seizures, coma or even death of the mother, baby, or both. Advanced preeclampsia prevents the uterus from getting enough blood, which can restrict the growth of the baby. It is also the No. 1 cause of premature birth.
The Vitamin D Connection
Dr. Lisa M. Bodnar, an assistant professor of Epidemiology, Psychiatry, and OB-GYN for the Graduate School of Public Health and School of Medicine at the University of Pittsburgh, is also one of the authors of the study that connects vitamin D and preeclampsia. Dr. Bodnar says that vitamin D is a pro-hormone that is produced either in the skin through exposure to sunlight or ingested orally through diet or supplements.
"Vitamin D has diverse functions in the body," Dr. Bodnar says. "It was previously thought to be related to skeletal health (bone mineralization and calcium homeostasis), but recently, research has shown that vitamin D is important for countless cell systems in the body. Vitamin D is not just important for maternal and fetal bone health. Our research shows that a deficiency in vitamin D in the first half of pregnancy is associated with an increased risk of preeclampsia, a serious pregnancy complication that has implications for maternal and fetal health and well-being."
Dr. Bodnar says vitamin D is a regulator of genes important for the development of the placenta and the maternal blood circulation to the placenta and fetus. It is also a regulator of the immune response, and has anti-inflammatory properties. All of these things are thought to be abnormal in preeclampsia.
Michelle Collins, an instructor in Clinical Nursing, Nurse-Midwifery Specialty, at the Vanderbilt University School of Nursing, read the literature on the study. "The risk noted in this particular research was five times greater that a pregnant woman could develop preeclampsia, if she were vitamin D deficient, when compared to women who were not deficient in vitamin D," Collins says. "It is not yet clear what the association is between vitamin D deficiency and preeclampsia, but researchers feel that the deficiency plays a role in the pathway of preeclampsia."
According to Collins, a vitamin D deficiency can also cause other complications. "If a woman is deficient in vitamin D, she is at risk for developing osetomalcia, which literally means soft bones," Collins says. "Her new baby will also be at risk of developing rickets, which is a softening of the baby's bones. Since the fetus' level of vitamin D is dependent upon its mother's vitamin D level, a deficiency in the mother could obviously affect the fetus in a negative way. Though uncommon in the US, it is still seen."