Cleaning with disinfectants during pregnancy may increase a baby's risk of asthma and eczema, study suggests

• The more pregnant people use disinfectants at work, the more likely they are to have kids with asthma, a study found.
• The study included nearly 80,000 parent-child pairs in Japan between 2011 and 2014.

Pregnant women who use disinfectants regularly at work are more likely to have children who develop asthma or eczema by age 3, a large study out of Japan found.

While past research has linked disinfectant use with asthma and skin irritation in adults, the study is among the few that has looked at how sanitizing sprays and gels may affect pregnant women's future children.

The study can't prove that disinfectant use in pregnancy causes asthma and allergies, but given the products' increased used during the coronavirus pandemic, "it is of great public health importance to consider whether prenatal disinfectant exposure is a risk for the development of allergic diseases," the study authors write.

More disinfectant use was linked to a higher likelihood of asthma and eczema

To conduct the study, researchers looked at 2011-2014 data from 78,915 mother-child pairs to see if there was an association between occupational disinfectant use in pregnancy and allergic diseases in the children at age 3.

Nearly 88% of mothers reported no disinfectant exposure during pregnancy, and only 1.7% reported daily exposure. About 21% were healthcare professionals.

Overall, 7.7% reported an asthma diagnosis and 7.3% reported an eczema diagnosis in their children at 3 years old.

The study authors found that moms with daily exposure to disinfectants were 26% and 29% as likely to have toddlers with asthma and eczema, respectively, than moms never exposed to disinfectants. Moms who used the products occasionally — 1 to 6 times a week — were 18% as likely to have kids with asthma.

After further analysis, the authors found the increased risk didn't seem to be accounted for by other factors like family allergy history, smoking and alcohol consumption, maternal stress, night-shift work, occupation, household income, breastfeeding, daycare attendance, and whether moms returned to work after a year. (Just under half of them did.)

The study, led by Dr. Reiji Kojima of the University of Yamanashi, was published Monday in the journal Occupational and Environmental Medicine.

Disinfectants may affect the developing fetus's immune system

The study authors offered a few explanations for their findings. For one, disinfectants can change the bacteria on a mom's skin, which may influence the newborn's gut microbiome. Another possibility: the products may affect the fetus's immune system, making them vulnerable to asthma upon toddlerhood.

Finally, the results could simply reflect that the moms more likely to use disinfectants are also more likely to get their kids early diagnoses of conditions like asthma.

There's room for error in the findings, too, since the study relied on mom's self-reports of disinfectant use and medical diagnoses. It also didn't differentiate between types of disinfectants.

Still, the authors write, their findings suggest disinfectant exposure during pregnancy "exerts an effect on allergies in offspring regardless of whether the mother returns to work when the child is 1 year old, and suggest an effect by exposure during pregnancy alone."