Five studies (n=7,225) were included in the review: 2 RCTs (n=5,783) and 3 observational studies (n=1,442).
The small number of included studies meant that the funnel plot was not informative, so publication bias could not be excluded. Loss to follow-up was considerable in 4 of the 5 included studies.
There was greater heterogeneity among studies conducted in children under 12 months of age (I-squared 53%) than those conducted in older children (I-squared <10%). Studies were therefore stratified by age, with only studies in children aged over 12 months (4 studies: 2 RCTs, 2 observational studies) being statistically pooled. These gave a pooled estimate of a -1.92 mmHg reduction (95% CI: -3.14, -0.71) in offspring systolic BP associated with calcium intake.
Three heterogeneous studies (1 RCT, 2 observational studies) in children aged less than 12 months all showed generally favourable effects on offspring systolic BP, though only two of these effects (both from observational studies) were statistically significant.