Vitamin D Deficiency in the Pregnant Population at University Hospital Birmingham: Does It Justify Universal Screening?

TL;DR

This study finds high vitamin D deficiency in pregnant women in Birmingham, suggesting universal screening may be needed due to limited effectiveness of current risk-based approaches.

Contribution

The study provides evidence that traditional risk factors poorly predict vitamin D deficiency in pregnant women, supporting the case for universal screening.

Findings

61.7% of pregnant women tested had insufficient or deficient vitamin D levels.

23% of women had severe vitamin D deficiency, exceeding expected rates.

Multiparity was the only significant risk factor for vitamin D deficiency.

Abstract

Background: Vitamin D deficiency is a growing global health concern, particularly among pregnant women, due to its associations with adverse maternal and neonatal outcomes. Birmingham represents a unique high-risk population with substantial ethnic diversity and socioeconomic deprivation, both of which may predispose to low vitamin D levels. This study aimed to determine the prevalence of vitamin D deficiency among pregnant women attending antenatal care at a large tertiary hospital and to evaluate whether risk-based screening adequately identifies deficient individuals.

Methods: This retrospective observational study included pregnant women who underwent serum 25-hydroxyvitamin D (25(OH)D) testing at University Hospital Birmingham between January and December 2022. A total of 2,757 records were reviewed to determine the overall prevalence. A randomly selected cohort of 300 women (100 normal, 100 mildly deficient, and 100 severely deficient) with complete clinical data was used to evaluate demographic and clinical risk factors. Vitamin D status was categorized according to the UK Public Health/National Institute for Health and Care Excellence (NICE) criteria. Statistical analyses included one-sample t-tests and chi-squared tests, with p < 0.05 considered significant.

Results: Among 2,757 women tested, 1,701 (61.7%) had insufficient or deficient vitamin D levels, significantly exceeding the 60% threshold (p = 0.034). Severe deficiency (<25 nmol/L) was present in 634 women (23%), also significantly higher than the hypothesized 21% prevalence (p = 0.006). In the 300-patient comparison cohort, the mean age was 29.94 ± 6.73 years, and the mean body mass index (BMI) was 29.33 ± 7.72 kg/m². Distribution of age, BMI, ethnicity, deprivation index, and comorbidities did not differ significantly across vitamin D categories, with all p-values > 0.05. No traditional risk factor showed a significant association with vitamin D status. Parity was the only variable significantly associated with vitamin D status (p = 0.002).

Conclusion: Vitamin D deficiency is highly prevalent among pregnant women in this ethnically diverse Birmingham population. Most classical risk factors did not reliably predict deficiency, although multiparity emerged as a significant contributor. Given the high burden of deficiency, low cost of testing, and limited discriminatory value of existing risk-based criteria, universal vitamin D screening at booking may be justified. Further prospective studies are needed to evaluate the impact of universal testing and targeted supplementation on maternal and neonatal outcomes.