Association between maternal vitamin D status during late pregnancy and acute lower respiratory tract infections and acute diarrheal disease during infancy - A cohort study.

Background: Acute lower respiratory tract infection (ALRI) and acute diarrheal disease (ADD) are the leading causes of mortality in children globally. There is emerging evidence of an association between maternal hypovitaminosis D and ALRI/ADD during infancy.

Objective: To determine whether maternal hypovitaminosis D (25(OH)D [<20 ng/ml] during late pregnancy is associated with increased risk of ALRI/ADD in their offspring during infancy.

Methods: This South Indian hospital-based, ambispective cohort study included 140 mother-baby dyads with known maternal vitamin D status before delivery in late third trimester (72 mothers with hypovitaminosis D and 68 mothers with adequate vitamin D level). Babies with cord blood vitamin D deficiency were treated as per consensus guidelines and those with adequate levels were supplemented with 400 IU vitamin D daily for 1 year. All infants were followed up at 6,10,14 weeks and 6, 9, 12 months for the occurrence, frequency, and severity of ALRI (pneumonia, bronchiolitis, viral induced wheezing) and ADD.

Results: Overall incidence of ALRI was 0.23 per child year during infancy. Incidence of ALRI was 0.12 per child year in adequate maternal vitamin D group versus 0.32 per child year in maternal hypovitaminosis D group (p value = 0.024) and that of bronchiolitis/viral wheeze was 0.07 per child year in adequate maternal vitamin D group versus 0.21 per child year in maternal hypovitaminosis D group (p value = 0.047). Cox regression analysis with maternal hypovitaminosis D level as predictor variable, adjusted for gestational age at birth and other covariates, revealed a hazard ratio of 3.18 (95 % CI: 1.17-8.65, p = 0.023) and 3.63 (95 % CI 1.36-9.65, p = 0.010) for ALRI and ADD respectively. No increased risk for occurrence of pneumonia was observed and none had severe pneumonia.

Conclusion: Maternal hypovitaminosis D is associated with increased risk of ALRI and ADD in their babies during infancy. Routine screening of pregnant women at risk for hypovitaminosis D and supplementation based on 25(OH)D level may decrease the burden of ALRI, for which further studies are needed.