Populations at risk of preeclampsia should be taking calcium supplements, but the pill-taking regimen can be complex. A recent study investigates whether the introduction of a much simpler regimen could increase adherence and supplement intake.

Preeclampsia is a complication during pregnancy involving the onset of high blood pressure and often leads to liver and kidney damage. If left untreated, preeclampsia can lead to serious and often fatal, complications for both the mother and baby. It is a major contributing factor to maternal and perinatal mortality.

While the complete pathogenesis of preeclampsia remains unknown, women living in populations with inadequate calcium intake have an increased risk of preeclampsia. The World Health Organization (WHO), based on evidence elucidated from systemic reviews of efficacy trials, highly recommends women in these populations to take calcium supplements daily as part of an existing antenatal care.

However, poor adherence is common due to a complicated recommended calcium supplement regimen, which includes a daily dose of elemental calcium of 1500 – 2000 mg divided into three doses and preferably taken with food. The situation gets even more complicated, however, as iron-folic acid supplementation has already been widely implemented. Calcium inhibits the absorption of iron in the body, and the two minerals should not be taken together. To reduce the negative effects of iron-calcium interaction on the absorption of iron, it is suggested that iron and calcium supplements are taken separately, leading to the complex pill-taking protocol.

A team of international scientists recently published a study in the Journal of Nutrition examining whether simpler regimens with lower daily dosages could potentially increase adherence and therefore lead to an increased supplement intake overall. The study compared the average daily supplement intake of two different regimens in a randomized trial which included 990 pregnant women between 16 and 30 weeks of gestation from 16 primary health care facilities in rural Kenya.

The standard regimen involved taking 500 mg calcium supplements three times per day, whereas the low-dose included 500 mg calcium supplements taken only two times per day. Both included taking a separate iron-folic acid supplement. The primary outcome was measured by pill counts after four and eight weeks from the time of recruitment.

With an 80% adherence rate, the results initially showed no difference in adherence between the two regimens. The overall difference in intake was 388 mg of elemental calcium, with women who were assigned the standard regimen with a higher dose of calcium consumed an average of 1198 mg of elemental calcium, compared to the lower-dose regimen women who consumed an average of 810 mg of elemental calcium.

The rates of adherence after the eight-week follow-up did, however, decrease for the standard regimen group compared to the lower-dose group. The WHO guidelines recommend calcium supplementation should be adhered to for the last 20 weeks of pregnancy, therefore, a limitation of this study is the second follow-up was after only eight weeks. It is unknown if the adherence rate would continue to decline with time and if there was a difference between the two groups.

The results showed that contrary to the hypothesis, a simpler regimen did not result in higher supplement intake, nor did it affect the adherence rate. Instead, it resulted in a significantly lower intake than the WHO guidelines which recommended a daily dose of 1500 – 2000 mg elemental calcium. However, it was noted by the authors that the standard higher dose regimen may have been more effective given it was administered under the clinical setting of the trial.

Future studies are necessary to elucidate the relationship between calcium supplementation and the risk of preeclampsia. Further studies should examine the cost-effectiveness and adherence levels of implementing simpler antenatal regimens and the impact this has on addressing perinatal deaths due to preeclampsia in low-income countries such as Kenya, where calcium intake among the population is typically low.

Written by Lacey Hizartzidis, PhD


Omotayo MO, Dickin KL, Pelletier DL, Mwanga EO, Kung’u JK, Stoltzfus RJ. A Simplified Regimen Compared with WHO Guidelines Decreases Antenatal Calcium Supplement Intake for Prevention of Preeclampsia in a Cluster-Randomized Noninferiority Trial in Rural Kenya. J Nutr. 2017 Sep 6. pii: jn251926. doi: 10.3945/jn.117.251926.

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