A study conducted by a team of researchers from St. John’s Research Institute and Medical College has found that the required dose of calcium for risk-reduction of preeclampsia in pregnant women could be reduced to 500 mg/day, provided there is good compliance.
This is in contrast with the World Health Organisation’s (WHO) recommendation of 1,500-2,000 mg of calcium per day during pregnancy, particularly in populations with low dietary calcium intake, such as India. The study was recently published in the New England Journal of Medicine.
Preeclampsia (PE) is a hypertensive disorder that typically starts after the 20th week of pregnancy, and manifests with an increased blood pressure and the appearance of protein (albumin) in the mother’s urine. The incidence of PE during pregnancy varies from 5% -15% in India.
The severe form of preeclampsia is eclampsia, which varies from 0.18% to 3.7 % in India and is characterised by seizures, and even mortality in some cases. Preterm births (PTB) occur in up to 10%-20% of pregnancies in India. Preeclampsia and eclampsia rank second to haemorrhage (an acute loss of blood) as a specific, direct cause of maternal mortality. Preeclamptic mothers are at a higher risk of developing cardiovascular diseases such as chronic hypertension, ischemic heart disease, and stroke later in life.
11,000 women
The study was conducted on 11,000 nulliparous pregnant women from 2019 to 2022 by a team of researchers led by Pratibha Dwarkanath and Anura Kurpad from St. John’s Research Institute and St. John’s Medical College, respectively.
The Indian study was part of two independent trials on similar numbers of women - the other trial was conducted in Dar es Salaam, Tanzania. Both trials were funded by the Bill and Melinda Gates Foundation, in collaboration with the Harvard T.H. Chan School of Public Health.
The study found that the required dose of calcium for risk-reduction of preeclampsia could indeed be reduced to 500 mg/day, which only requires the intake of one tablet/day. “Going by the WHO recommendation, the supplementation of 1,500 mg/day means taking three tablets a day as each calcium tablet only can contain 500 mg of calcium,” Dr. Dwarkanath told The Hindu.
The study found that low-dose calcium supplementation was as effective as high-dose calcium supplementation in preventing the risk of PE and PTB. “In the India trial, the incidence of preeclampsia was 3% among women taking 500 mg of calcium per day and 3.6% among women taking 1,500 mg of calcium per day,” she said.
“The striking findings of this large-scale non-inferiority trial, showing no difference on risk-reduction of PE between daily doses of 500 and 1,500 mg of calcium, is both cost-effective and easy to comply with,” she said.
She also pointed out that there are further benefits of calcium, beyond blood pressure. Since calcium supplementation could reduce uterine smooth-muscle contractility, it could also lower the risk for preterm labour.
Prof. Kurpad said that reducing the dose of calcium would itself improve compliance, which is critically important in populations which have a low calcium intake. “Given that this effective dose of 500 mg of calcium is a single tablet, and less than the current national recommendation of 1,000 mg/day, this trial should inform the policy on reducing the dose of calcium, specifically to minimise the incidence of PE and PTB in pregnancies in India and worldwide,” he said.
“Apart from the low-dose calcium supplementation for risk reduction, efforts to motivate women for institutional deliveries, nutritional counselling, and their compliance with the supplementation program are pivotal,” he added.
Published - January 16, 2024 09:14 pm IST