Specific airway resistance according to early maternal vitamin D status during pregnancy in children aged 5 to 6 years old from the FEPED cohort (RESPIFEPED).

There are conflicting results on the association between maternal vitamin D concentrations during pregnancy and respiratory outcomes for their offspring. However, published studies have mainly focused on the second and third trimesters of pregnancy or on high-risk population. The main objective of this study was to evaluate the association between vitamin D plasma concentrations in the first trimester (T1) of pregnancy and effective specific airway resistance (sR_eff) for children aged 5 to 6. Secondary objectives were to evaluate this association in the third trimester (T3) and in cord blood as well as the association between vitamin D plasma concentration and interrupter resistance (Rint), bronchiolitis, asthma, and allergen sensitization at the same time points. This multicenter study included 140 children born from women enrolled in the FEPED cohort. Associations between sR_eff and maternal vitamin D plasma concentration at T1, T3 of pregnancy, and in cord blood were assessed. sR_eff was analyzed according to in-utero and postnatal exposure to tobacco smoke and the occurrence of an episode of bronchiolitis before 6 months of age. The impact of maternal vitamin D status on the secondary outcomes was similarly assessed. sR_eff values were not associated with the maternal vitamin D status at T1 and T3, nor asthma status or allergen sensitization.

Conclusion: In a cohort of young children, airway resistance and asthma were not associated with early vitamin D deficiency during pregnancy.

Trial registration: This study is registered with the ClinicalTrials.gov identifier NCT03229317.

What is known: • There are conflicting results on the association between maternal vitamin D concentrations during pregnancy and respiratory outcomes for their offspring. However, published studies have mainly focused on the second and third trimesters of pregnancy or on high-risk population.

What is new: • In a cohort of 5- to 6-year-old children assessed prospectively, there was no significant difference in sReff or any other lung function measurements depending on maternal vitamin D status during the first trimester of pregnancy.