Imdad et al. BMC Public Health 2011, 11(Suppl 3):S18 http://www.biomedcentral.com/1471-2458/11/S3/S18 Page 11 of 13 Figure 7 Funnel plot of studies evaluating effect of calcium supplementation during pregnancy in reducing risk of pre-eclampsia in developing countries. severe morbidities (Additional File 1). It is important to note that maternal calcium supplementation during pregnancy is not only effective in reducing neonatal mortality but also morbidities later in childhood. A review by Bergel and Barros had reported that offspring of women who were supplemented with calcium during pregnancy had low incidence of hypertension in child- hood [52]. Our review has certain limitations. In two of the included studies [45,46], the comparison group did not receive the placebo but the participants were simply observed as controls. This could have biased the results in favor of intervention [16]. We did not look at the side effects related to calcium supplementation during pregnancy. The previous reviews, however, have shown that it is not associated with any particular harmful effects [10]. Findings of this review and those of previous reviews gave conclusive evidence on effectiveness of calcium supplementation during pregnancy in reducing maternal gestational hypertensive related disorders in populations with low baseline calcium intake [8,11]. Future research should focus on delivery platforms, regimens and programmatic aspect of the intervention. It would be relevant to assess the bioavailability of calcium when delivered for example via dietary modification or food fortification. It is important for example to determine effectiveness of calcium supplementation by dietary modification at places where baseline calcium intake is from dairy products compared with those where it is mostly taken in from vegetarian sources. It is also important to calculate an internationally accepted value to define adequacy given the large variations in calcium recommendations in different countries of the world. Implementation of recommendation of calcium sup- plementation to all pregnant women in developing countries poses a major challenge to policy-makers and program managers of these countries. It is impor- tant to take steps for procurement of the preparation, storage, distribution, quality-control, and compliance assurance with daily supplements to large numbers of pregnant women. It is also important to consider cul- tural, financial, and educational barriers to changing policy and lessons should be learnt from practices of previous programs like iron+folic acid supplementation schemes in these countries. Lack of infrastructure and