A mother who pulls out a bottle of hand sanitizer or a father who washes everything with a baby wipe might actually be doing more harm than good.

A study published by Dr. Charlotte Braun-Fahrlander on March 19 in The New England Journal of Medicine adds to the growing evidence supporting the relatively new “hygiene hypothesis.”

The premise for the hypothesis is that modern advances like indoor plumbing, antibiotics and cleaner homes may be contributing to higher levels of allergy, asthma and eczema by decreasing childhood infection.

The new study, headed by Dr. Braun-Fahrlander of the Institute of Social Preventive Medicine in Basel, Switzerland, found that children raised on farms were less likely to develop asthma and allergies than children who did not come from farms.

Furthermore, previous studies also uphold the notion that children who grow up with pets, come from large families or who attend daycare — all breeding grounds for germs — are less likely to develop asthma.

The study included 812 children, ages 6-13, 319 from farms and 493 from non-farming homes in rural parts of Austria, Germany and Switzerland.

Among the farm children, 4.1 percent reported hay fever, and 3.1 percent reported any type of allergy-related asthma. Among the children not from farms, 10.5 percent developed hay fever, and 5.9 percent had an allergy-related asthma.

Part of the study included measuring substances called endotoxins in the children’s mattresses. Endotoxin is a component of most bacteria; levels of endotoxins tend to be higher on farms.

The children whose mattresses had the lowest endotoxin levels ­— all of which were found in non-farming homes — had the highest rate of hay fever — about 15 percent.