Maternal Calcium Intake at 36 Weeks' Gestation and Pre-Eclampsia Risk—A Cohort Study

Objective

The objective of this study is to examine the association between dietary calcium intake (Ca) and pre-eclampsia (PE).

Design

Cohort study.

Setting

Inner-city hospital.

Population

A total of 2838 women with singleton pregnancies at 35⁺⁰–36⁺⁶ weeks' gestation, including 96 (3.4%) who subsequently developed PE.

Methods

Online 24-h dietary recall questionnaire was used to measure Ca intake. In the low (< 700 mg/d) vs. adequate (≥ 700 mg/d) Ca intake groups, we compared the prevalence of PE-associated maternal risk factors and the incidence of PE. In multivariate regression, we examined the low Ca intake and PE relationship, adjusted for established PE risk factors (including blood pressure and angiogenic biomarkers) and any additional factors associated with low Ca intake specifically.

Main Outcome Measure

PE.

Results

Overall, 405 (14.3%) women had low Ca intake. Low (vs. adequate) Ca intake was associated with a higher incidence of PE (6.2% vs. 2.9%; odds ratio 2.2, 95% confidence interval 1.3–3.7), as well as more prevalent risk factors for PE, including Black ethnicity (34.1% vs. 11.8%), South Asian ethnicity (10.1% vs. 7.2%), high body mass index (29.8 vs. 28.3 kg/m²) and more deprived index of multiple deprivation (54.3% vs. 35.5%). In multivariate regression adjusting for other PE risk factors, low Ca intake was no longer associated with PE (OR 1.7, 95% CI 0.9–3.2).

Conclusions

Although some contribution from low Ca to the development of PE cannot be ruled out, after accounting for maternal characteristics, medical history and deprivation, low Ca intake did not make an independent contribution to the development of PE in this population of mixed-ethnicity women.