Calcium supplementation in pregnancy and its impact on blood pressure in children and women: Follow up of a randomised controlled trial

Background: Follow up of participants in trials of antenatal calcium supplementation has reported an impact on blood pressure among mothers and children. Aims: To determine whether blood pressure at 4-7 years follow up would be lower for calcium-supplemented mothers in the Australian Calcium Trial (ACT) and for their children. Methods: This follow up targeted 414 of the original ACT participants with liveborn infants who lived in South Australia. Mothers and their children attended the Women's and Children's Hospital for anthropomorphic examination. Information on lifestyle factors was collected by questionnaire. Descriptive statistics examined differences between respondents and non-respondents and multiple regression models examined associations with blood pressure. Results: Blood pressure and body measurements were available on 45 and 43% of eligible women and children, respectively; questionnaire data were available on 50% of this cohort. At follow up, there were no differences between treatment groups in blood pressure in the women or their children. Both children of women who had high blood in pregnancy (pre-eclampsia or pregnancy-induced hypertension) and the women themselves had higher systolic and diastolic blood pressure at follow up. Among children, there was a trend towards an interaction with the treatment group with both systolic and diastolic blood pressure at follow up. Conclusion: There is no evidence that the impact of calcium supplementation in reducing the risk of high blood pressure in pregnancy is sustained 4-7 years after the index pregnancy either in woman or in their children; however, calcium supplementation may lower blood pressure in children of pregnant women with hypertension.