Blood pressure in 3-year-old girls associates inversely with umbilical cord serum 25-hydroxyvitamin D: an Odense Child Cohort study.

Background Low foetal vitamin D status may be associated with higher blood pressure (BP) in later life. Objective To examine whether serum 25-hydroxyvitamin D2+3 (s-25OHD) in cord and pregnancy associates with systolic and diastolic BP (SBP; DBP) in children up to 3 years of age. Design Prospective, population-based cohort study. Methods We included 1594 singletons from the Odense Child Cohort with available cord s-25OHD and BP data at median age 3.7 months (48% girls), 18.9 months (44% girls) or 3 years (48% girls). Maternal s-25OHD was also assessed at gestational ages 12 and 29 weeks. Multiple regression models were stratified by sex a priori and adjusted for maternal educational level, season of birth and child height, weight and age. Results In 3-year-old girls, SBP decreased with -0.7 mmHg (95% CI -1.1; -0.3, P = 0.001) and DBP with -0.4 mmHg (95% CI -0.7; -0.1, P = 0.016) for every 10 nmol/L increase in cord s-25OHD in adjusted analyses. Moreover, the adjusted odds of having SBP >90th percentile were reduced by 30% for every 10 nmol/L increase in cord s-25OHD (P = 0.004) and by 64% for cord s-25OHD above the median 45.1 nmol/L (P = 0.02). Similar findings were observed between pregnancy s-25OHD and 3-year SBP, cord s-25OHD and SBP at 18.9 months, and cord s-25OHD and DBP at 3 years. No consistent associations were observed between s-25OHD and BP in boys. Conclusion Cord s-25OHD was inversely associated with SBP and DBP in young girls, but not in boys. Higher vitamin D status in foetal life may modulate BP in young girls. The sex difference remains unexplained.