Want an asthma-free child Get a pet while you are pregnant
Babies who have indoor prenatal pet exposure have a pattern of lower levels of an antibody linked to asthma and allergies
Mothers who spend time with pets during their pregnancy are less likely to have children with allergies and asthma, a study has revealed.
But the race of the child – and how they were delivered – also plays a part.
Researchers at the Henry Ford Hospital in Detroit found that babies who have indoor prenatal pet exposure have a pattern of lower levels of the antibody Immunoglobulin E, or IgE, between birth and their second birthday.
IgE is linked to the development of allergies and asthma.
Levels of the antibody were, on average, 28 per cent lower during infancy in babies who had indoor prenatal pet exposure compared to babies from pet-free homes.
However IgE levels were 33 per cent lower in those babies from European, Asian or Middle Eastern descent compared to 23 per cent in kids who were African-American.
And the levels were also lower in infants who had indoor prenatal pet exposure and were born vaginally, compared to those born by caesarean section.
Dr Christine Cole Johnson, chair of Henry Ford's Department of Public Health Sciences and senior author of the study said: 'We believe having a broad, diverse exposure to a wide array of microbacteria at home and during the birthing process influences the development of a child's immune system.'
Dr Johnson added that the findings support the so-called hygiene hypothesis.
This is the theory that early childhood exposure to infectious agents affects the immune system's development and onset of allergies and asthma.
Dr Johnson theorised that babies born through the birth canal are exposed to a higher and more diverse burden of bacteria, further boosting the immune system's protection against allergies.
The Detroit hospital's findings support the so-called hygiene hypothesis, which theorises that early childhood exposure to infectious agents affects the immune system's development and onset of allergies and asthma
She said that 'genetic variants' could explain the higher levels of IgE levels in African American newborns.
She added: 'Our findings may provide insight into the biological mechanisms that increase the risk for allergic disorders.'
Henry Ford researchers followed 1,187 newborns August 2003 and November 2007 and collected blood samples for measuring IgE levels at birth, six months, one year and two years.
Of the birth mothers, 62 percent were African American and 33 percent were European Americans.
Of the babies born, 751 were delivered vaginally and 436 were delivered cesarean.
There was at least one indoor pet in the homes of 420 mothers.
The findings are published online at the Journal of Allergy and Clinical Immunology.