A randomized, triple-blind, placebo-controlled trial is currently being conducted to evaluate the effectiveness of calcium carbonate supplementation in preventing preeclampsia among high-risk pregnant women. The study, taking place in Brazil, is comparing two different sources of calcium carbonate, including a novel source derived from oyster shells.
Trial Design and Intervention
The trial includes three groups: two intervention groups (EG I and EG II) and a control group. All participants receive 100 mg of acetylsalicylic acid daily. EG I receives 1000 mg of commercial-grade calcium carbonate, while EG II receives 1000 mg of calcium carbonate derived from Crassostrea sp. oysters. The control group receives a placebo.
The calcium carbonate from oyster shells is being developed through a collaboration between the Federal University of Sergipe and the Federal University of Alagoas. This approach aims to utilize sustainable resources, as these shells are often discarded by fishing communities. The capsules undergo rigorous testing to ensure quality, adhering to Brazilian Pharmacopoeia guidelines.
Participant Monitoring and Adherence
Participants are closely monitored for adverse reactions, and they have the right to withdraw from the study at any time. To enhance medication adherence, pharmacists provide ongoing support and address any concerns. Weekly phone calls are made to track treatment progress. Adherence is measured using the Brief Medication Questionnaire (BMQ).
Participants who were on other medications prior to or during pregnancy continue their treatments, provided there are no interferences with the study interventions. Potential drug-drug interactions are evaluated on a case-by-case basis. Non-adherence to the allocated intervention results in withdrawal from the trial.
Outcomes and Sample Size
The primary outcome of the trial is the incidence of preeclampsia. Secondary outcomes include maternal and fetal health indicators that may be related to the effects of calcium carbonate. Data collection spans from May 2024 to March 2026, with participant recruitment continuing until June 2025.
The study aims to recruit at least 519 patients to account for a 10% dropout rate, ensuring adequate power to detect a statistically significant difference. The sample size calculation is based on detecting a 50% reduction in preeclampsia incidence, assuming a 30% incidence rate in high-risk pregnant women. A two-sided t-test with a familywise α level of 0.05 is used, with Sidak correction applied for multiple comparisons.
Post-Trial Care
All participants who complete the study, whether regularly or prematurely, are referred to the healthcare team for continued monitoring and full support.
