Pet keeping has been linked with decreased risk of allergic sensitization, which has been associated with the Hygiene Hypothesis, and more recently, by ourselves and others, to particular home microbiome patterns. Another factor possibly associated with pet ownership is increased Vitamin D among family members as pet keeping may be correlated with lifestyles involving increased outdoor exposure, such as dog walking. Prenatal vitamin D inadequacy has been hypothesized as a risk factor for pediatric atopy and asthma.
Methods:
To investigate potential relationships between household pet exposure and cord blood vitamin D concentrations, we analyzed information from a large, geographically-based, general risk birth cohort. Household pets were assessed during pregnancy and serum level of 25 (OH)D (25-hydroxyvitamin D) in cord blood was used as the measure of vitamin D and a marker of maternal level. Because of notable differences in vitamin D concentrations between African Americans and Whites, analyses were stratified by race.
Results:
A total of 1055 newborns were included in the study: 62.4% were African Americans and 49.4% were female. For Whites, but not African Americans, having no pet compared to 1 or >1 pet during pregnancy was associated with lower cord blood vitamin D concentrations (37.7, 45.2, 47.0 nmol/L, respectively, p=0.001). Considering type of pet, the relationship for no pet compared to 1 or >1 dog (37.7, 46.1, 49.9 nmol/L, respectively, p=0.001) was similar to that for no pet versus 1 or >1 cat (37.7, 43.0, 46.5 nmol/L, respectively, p=0.065).
Conclusions: In a large ethnically diverse cohort of newborns, the presence of a pet in the home during the prenatal time period was associated with higher cord blood vitamin D, but only among Whites. This racial difference may reflect an impact on pet owner behavior resulting in increased outdoor exposure that is limited to lighter skinned individuals. However, as the effect doesn’t vary by cats versus dogs, differences by race in factors correlated with pet ownership or variations in pet keeping styles may be more important. Vitamin D should be considered in studies of pets and atopic conditions.