Can a cold during pregnancy affect your unborn baby?

Moms-to-be should take extra precaution around those who are sniffling and sneezing this winter, experts say.

According to a new study published in Annals of Allergy, Asthma and Immunology (ACAAI) , the more colds and viral infections a woman has during pregnancy, the higher the risk of her baby developing allergy and asthma in childhood.

“We know that allergy and asthma can develop in the womb since genetics play a factor in both diseases,” said Dr. Michael Foggs, ACAAI president, in a news release.

Past studies have shown that having two parents with allergies means a child has a 75 percent chance of developing allergies. Even if only one parent has allergies, a child’s risk is still nearly 40 percent.

“But this study sheds light about how a mother’s environment during pregnancy can begin affecting the children before birth,” Dr. Foggs says.

Researchers recruited over 500 pregnant women and followed them over a five-year period. Each year, the mothers completed questionnaires and each child went through a health assessment.

The results revealed that the more illnesses a woman had during pregnancy, such as repeated common colds, the more likely her child would have asthma. Additionally, babies exposed to allergens were more likely to be sensitive to them.

“Children who had early exposure to allergens, such as house dust and pet dander, had increased odds of becoming sensitized [to the allergens] by age 5,” said Dr. Mitch Grayson, ACAAI deputy editor, in a news release.

The researchers concluded that a mother’s colds shape the baby’s utero environment and have lasting effects through childhood development.

And while it’s unlikely that just one cold will harm your baby, make sure you’re doing what you can to protect yourself from infections, says Dr. Robert Rosenberg, medical director of obstetrics and gynecology at Advocate Condell Medical Center in Libertyville, Ill.

“Get plenty of sleep, wash your hands often, stay away from people who are sick, and get an annual flu vaccine as the CDC recommends,” Dr. Rosenberg says.