Medics have discovered a way to significantly reduce the risk of preterm labor

During pregnancy, women are at risk of developing various complications. Preeclampsia, one of the most important causes of maternal and perinatal morbidity and mortality, occurs in 2-8% of cases. Large doses of calcium have been recommended to reduce the risk of developing this pathology. Now scientists have tested whether they can be reduced while maintaining effectiveness.

Preeclampsia is a complication of the second half of the gestational process, that is, it does not develop before the 20th week of pregnancy. This pathology is characterized by an increase in vascular pressure and the appearance of protein in the urine. In some pregnant women, preeclampsia can manifest with arterial hypertension and symptoms of functional failure of one of the vital organs (kidneys, heart, brain, placenta). Maternal mortality is 12 times higher when the pathology develops before the 28th week of pregnancy. 

It is known that sometimes even the most unexpected lifestyle changes can significantly reduce its frequency - for example, it is known that oral sex with certain features correlates with a significantly reduced risk of pre-eclampsia.

To reduce the risk, the World Health Organization has recommended that pregnant women from populations with low dietary calcium intake take 1,500 to 2,000 milligrams of the substance per day as a supplement, divided into three doses. The organization estimates that this halves the risk of preeclampsia in pregnant women and reduces the risk of preterm birth by 25 percent. However, the complexity of the dosing scheme has led to difficulties in implementation.

Now, researchers from the Harvard T. Chan School of Public Health have conducted two independent randomized trials in India and Tanzania. They compared the effectiveness of a daily dose of 500 milligrams of calcium versus a dose of 1,500 milligrams. The results are published in The New England Journal of Medicine.

The study involved 11,000 pregnant women from India and the same number from Tanzania. All had a first pregnancy, which increased the risk of pre-eclampsia. Beginning in the 20th week of pregnancy, the women received a supply of daily calcium supplements. In one group, participants took three 500-milligram pills; in the other group, they took one 500-milligram calcium tablet and two placebo pills. The medics monitored their health during clinic visits every month, during labor and six weeks after the baby was born.

The scientists concluded that low doses of calcium are as effective as high doses. In a study in India, the incidence of preeclampsia was 3 percent among women who took 500 milligrams of calcium a day and 3.6 percent among women who took 1,500 milligrams of calcium. In a study in Tanzania, the incidence of pre-eclampsia was 3% and 2.7%, respectively.

Data on preterm labor have been mixed. In a study in India, the incidence of preterm birth was 11.4% in women taking 500 milligrams of calcium per day and 12.8% in women taking 1500 milligrams of calcium, indicating a similar effect of both doses.

In the Tanzania study, the preterm birth rates were slightly different: 10.4% and 9.7%, respectively. However, when the researchers combined the data from both studies, they found that the effect of low-dose supplementation on preterm labor was not significantly different compared to taking high doses.  

Earlier, a team of scientists from the UK, US, Croatia and Sri Lanka found that nausea and vomiting in pregnant women is linked to the maternal body's hypersensitivity to the hormone GDF15, which is produced in large amounts in fetal tissues.