Maternal Serum Vitamin D Levels and Pre-eclampsia among Kenyan Pregnant Women: protocol for a matched case-control pilot study

Abstract

Background Preeclampsia is considered among the top causes of avoidable maternal death in low- and middle-income countries (LMICs), making it a significant social, economic, and healthcare system burden. Maternal vitamin D deficiency could be a key factor in the pathophysiology of pre-eclampsia. Worldwide, the link between vitamin D deficiency and pre-eclampsia still has mixed results, with minimal data on this topic from Africa. This pilot study aims to determine the association between maternal serum vitamin D levels in pregnancy and the risk of preeclampsia in a Kenyan population. Methods This case-control study will be single-centered and conducted at Moi Teaching and Referral Hospital (MTRH), Kenya. A total of 120 women with confirmed viable intrauterine pregnancies at ≥28 weeks’ gestation will be included. Sixty with pre-eclampsia (PE) as cases and 60 normotensive controls matched by parity, age, and gestation. Open Peer Review Approval Status AWAITING PEER REVIEW Any reports and responses or comments on the article can be found at the end of the article. VeriXiv Page 1 of 8 VeriXiv 2026, 3:6 Last updated: 21 MAY 2026Corresponding author: Kimbley Asaso Omwodo (kimbleyomwodo@alumni.harvard.edu) Author roles: Omwodo KA: Conceptualization, Formal Analysis, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Writing – Original Draft Preparation, Writing – Review & Editing; Kimani JN: Data Curation, Investigation, Project Administration, Resources, Software, Visualization; Nicodemus K: Data Curation, Investigation; Kioko DM: Data Curation, Investigation; Georgieva A: Supervision, Validation Competing interests: No competing interests were disclosed. Grant information: This work was supported by the Bill & Melinda Gates Foundation [grant ID: INV-033705] awarded to Kimbley Asaso Omwodo as part of the Supporting Women in Science (SWIS) program at the Aga Khan University-Institute for Global Health and Development. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Copyright: © 2026 Omwodo KA et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. How to cite this article: Omwodo KA, Kimani JN, Nicodemus K et al. Maternal Serum Vitamin D Levels and Pre-eclampsia among Kenyan Pregnant Women: protocol for a matched case-control pilot study [version 1; peer review: awaiting peer review] VeriXiv 2026, 3:6 https://doi.org/10.12688/verixiv.2676.1 First published: 02 Jan 2026, 3:6 https://doi.org/10.12688/verixiv.2676.1 Serum 25-hydroxyvitamin D [25(OH)D] will be quantified. The proportion of vitamin D deficiency (25(OH) D ˂30 nmol/L) among the study sample will be assessed. The vitamin D status among pregnant women with and without pre-eclampsia will be compared. Results We anticipate an enrollment of 120 pregnant women, 60 cases with PE and 60 matched controls. We hypothesize that pregnant women with PE will exhibit a significantly higher proportion of vitamin D deficiency compared to normotensive controls. Multivariable logistic regression is expected to demonstrate a significant association between vitamin D deficiency and odds of pre-eclampsia. Conclusion Maternal serum Vitamin D levels and any relationship with Preeclampsia among this cohort will be clarified