Joint Associations of Plasma Nutritional Biomarkers and Uterine Fibroids with Hypertensive Disorders of Pregnancy

Background: Hypertensive disorders of pregnancy contribute substantially to maternal morbidity and mortality, and occur with increased frequency among women with uterine fibroids. Biomarkers involved in oxidative stress and endothelial function, including folate, vitamin B12, vitamin D, and homocysteine, have been studied in relation to hypertensive disorders of pregnancy, but their relationship to fibroid-associated risk has not been well characterized, particularly in racially and ethnically diverse populations. Study Design: This study was a retrospective analysis of the Boston Birth Cohort, a prospective cohort recruited at a large urban medical center. The analytic sample included 722 women with complete data on hypertensive disorder status, uterine fibroid status, and plasma biomarker measurements. Uterine fibroids and hypertensive disorders of pregnancy were ascertained through physician-assigned diagnostic codes and ultrasound report review. Plasma folate, vitamin B12, vitamin D, and homocysteine were measured in maternal or cord blood and analyzed as continuous variables and quartiles. Multivariable logistic regression models were used to estimate independent associations, evaluate interaction terms, and assess joint exposure categories. Results: Of the 722 participants, 12% (86/722) had uterine fibroids and 10% (72/722) had a hypertensive disorder of pregnancy. Plasma micronutrient concentrations did not differ significantly by fibroid status. Women with hypertensive disorders of pregnancy had higher plasma homocysteine concentrations compared with those without (p=0.028). Hypertensive disorders of pregnancy were more common in the lowest folate quartile compared with the highest quartile (p=0.018) and in the highest homocysteine quartile compared with lower quartiles (p=0.031). In joint-effects analyses, higher odds of having a hypertensive disorder of pregnancy were observed among women with both uterine fibroids and low folate compared with women without fibroids and with adequate folate (p=0.027). No significant joint associations were observed for vitamin D, vitamin B12, or homocysteine. Conclusion: In this cohort, the co-occurrence of uterine fibroids and lower folate concentrations was associated with hypertensive disorders of pregnancy. This joint exposure delineates a subgroup that may be clinically relevant for future studies aimed at refining maternal risk characterization and exploring targeted nutritional supplementation strategies.