Dr. Bianca Schaub, leader of the research team at University Children's Hospital in Munich, Germany, conducted a study that showed that mothers who spent time on a farm, where they were exposed to animals and local milk, conferred more protection against allergies and asthma to their babies than mothers who were not exposed to farms. Schaub proposed that the greater number of microbes in a farm environment passed on to the baby via the mother, might build up the baby's immune system.
"The fetus in the womb is really an extension of mom," Doshi said. "Everything the mom is exposed to the fetus is exposed to."
But genetic makeup remains the classic starting point in determining what a child will and will not be susceptible to.
In one study combining genetics with circumstance, researchers from the University of South Carolina, determined that birth order correlates with the likelihood of having asthma or allergies. First-born children are more likely to have a different version of a gene involved in allergic development, one that leaves the oldest sibling more susceptible to developing asthma or allergies than their younger siblings. The chance of developing asthma or allergies persisted in the oldest child until at least age 10.
But one study showed that certain situations, not just physical environments, could also affect a child's immune system such that they were more or less susceptible to asthma and allergies.
Researchers at the University of California at San Francisco found a correlation between birth by Caesarean section and a weaker immune response that could put children at risk for developing asthma and allergies.
According to Doshi, it will also be key to continue these studies on the children as they grow older. Patterns of asthma or allergies in babies or young children are different than in older children. Continuing this research over time could help researchers understand how severe or lasting the prenatal effects are, could be the first step in developing effective preventive strategies, or even vaccines, for asthma and allergic diseases.
"We're beginning to learn more and more that genetics plays a v large role in asthma and allergies. And so does environment," Doshi said. "When you start combining [them] together, we are finding out that these go more and more hand in hand."