A study has found that pregnant women who take an average of more than 400 IU of vitamin D supplements daily reduce their risk of preeclampsia by 44.8% and preterm birth by 30%.
Preeclampsia, also known as pregnancy-induced hypertension, is a condition that occurs after 20 weeks of pregnancy and involves high blood pressure and proteinuria. It can lead to seizures and convulsions, and in severe cases, it can cause intrauterine growth restriction, oligohydramnios, or even fetal death. Treatment typically involves delivering the baby after 34 weeks of pregnancy, while antihypertensive and anticonvulsant medications are used before that point.
On Monday, Professor Khaled Moghib of Cairo University’s Faculty of Medicine in Egypt and his research team published their analysis of 33 studies released in August.
Pregnant participants in the high-dose vitamin D group took daily supplements ranging from 400 to 20,000 IU. In contrast, the control group consisted of pregnant women who consumed less than 400 IU of vitamin D daily. The IU (International Unit) measures biologically effective substances like hormones, vitamins, and vaccines and does not represent their absolute weight. The American Academy of Pediatrics recommends 400 IU of vitamin D per day for infants under six months old and 600 to 4,000 IU per day for adults.
The researchers measured the rates of preeclampsia and preterm birth between pregnant women who took vitamin D supplements and those who did not.
The serum 25-hydroxyvitamin D level, which indicates the vitamin D status in the blood, was approximately 32.42 nmol/L higher in the high-dose group than in the control group.
Based on this data, the research team further found that the high-dose group had a 44.8% lower risk of preeclampsia compared to the control group. The risk of preterm birth was also reduced by 30%.
However, there were no significant differences between the high-dose and control groups in the rates of low birth weight or the Apgar scores of newborns five minutes after birth.
The Apgar score assesses a newborn’s health immediately after delivery, evaluating factors such as skin color, pulse, respiration, muscle tone, and reflex responses. The score ranges from 0 to 10, with higher scores indicating better health.
The researchers explained, “Vitamin D can affect vascular endothelial dysfunction by improving vascular structure, elasticity, and intima-media thickness, decreasing blood pressure, and reducing oxidative stress.”
They added that this study is the first to show that vitamin D supplementation during pregnancy significantly reduces the risk of preeclampsia and preterm birth. However, they noted that further research is needed to clarify the effects of vitamin D on newborn health.
The study was published in the December issue of the international journal BMC Pregnancy and Childbirth.