Associations of Cord Blood Vitamin D and Preeclampsia With Offspring Blood Pressure in Childhood and Adolescence.Importance
 Maternal preeclampsia may be one of the early risk factors for childhood and adolescence elevated blood pressure (BP).  It is unknown whether the intergenerational association between maternal preeclampsia and offspring BP differs by cord blood vitamin D levels.


 Objective
 To assess the associations between maternal preeclampsia and offspring systolic BP (SBP) across childhood and adolescence and to test whether these associations vary by cord blood 25-hydroxyvitamin D [25(OH)D] concentrations (a biomarker of in utero vitamin D status).


 Design, Setting, and Participants
 This prospective cohort study analyzed 6669 SBP observations from 754 mother-child pairs from the Boston Birth Cohort, who were enrolled from December 1998 to June 2009.  Data were analyzed from October 2019 to March 2020.


 Physician-diagnosed maternal preeclampsia.  Plasma 25(OH)D concentrations measured in cord blood samples collected at delivery.


 Main Outcomes and Measures
 The SBP percentile was calculated based on the 2017 American Academy of Pediatrics hypertension guidelines.  Mean difference in SBP percentile in children born to mothers with vs without preeclampsia was compared across different cord blood 25(OH)D levels.


 There were 6669 SBP observations from the 754 children; 50.0% were female and 18.6% were born preterm.  Of the 754 mothers, 62.2% were Black and 10.5% had preeclampsia.  Median cord blood 25(OH)D was 12.2 (interquartile range, 7.9-17.2) ng/mL.  Maternal preeclampsia was associated with 5.34 (95% CI, 1.37-9.30) percentile higher SBP after adjusting for confounders.  This association varied by quartiles of cord blood 25(OH)D concentrations: the differences in SBP percentile comparing children born to mothers with vs without preeclampsia were 10.56 (95% CI, 2.54-18.56) for quartile 1 (lowest), 7.36 (95% CI, -0.17 to 14.88) for quartile 2, 4.94 (95% CI, -3.07 to 12.96) for quartile 3, and -1.87 (95% CI, -9.71 to 5.96) for quartile 4 (highest).  When cord blood 25(OH)D was analyzed continuously, children born to mothers with preeclampsia had 3.47 (95% CI, 0.77-6.18) percentile lower SBP per 5 ng/mL 25(OH)D increment.  These associations did not differ by child sex or developmental stages.


 Conclusions and Relevance
 In this study of a US high-risk birth cohort, maternal preeclampsia was associated with higher offspring SBP from early childhood to adolescence.  These associations were attenuated by higher cord blood 25(OH)D levels in a dose-response fashion.  Additional studies, including clinical trials, are warranted.
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