If you're thinking about adding a dog to the family, you have two good reasons to say "yes," say researchers from the University of Alberta. Their study found that babies from families with pets — 70 percent were dogs — had higher levels of two microbes that protect against allergies and obesity.

There is a catch, though. "There's definitely a critical window of time when gut immunity and microbes co-develop, and when disruptions to the process result in changes to gut immunity," said pediatric epidemiologist Anita Kozyrskyj.

Her team's research found that exposure to pets in the womb or up to three months after birth increases the amount of two bacteria, Ruminococcus, which has been linked to a reduced risk of childhood allergies, and Oscillospira, which has been linked to a lower risk of obesity.

"The abundance of these two bacteria were increased twofold when there was a pet in the house," said Kozyrskyj, adding that the pet exposure was shown to affect the gut microbiome indirectly — from dog to mother to unborn baby — during pregnancy as well as during the first three months of the baby's life. In other words, even if the dog had been given away for adoption just before the woman gave birth, the healthy microbiome exchange could still take place.

The study also found that the immunity-boosting exchange occurred even in three birth scenarios known for reducing immunity: C-section versus vaginal delivery, antibiotics during birth, and lack of breastfeeding.

In addition, the study suggested that pets in the house reduced the likelihood of the transmission of vaginal GBS (group B Strep) during birth, which causes pneumonia in newborns and is prevented by giving mothers antibiotics during delivery.

Kozyrskyj theorizes that one day there may be a "dog in a pill" to help prevent allergies and obesity.

"It's not far-fetched that the pharmaceutical industry will try to create a supplement of these microbiomes, much like was done with probiotics," she said.

Previous research has also found that children raised in homes with pets have fewer allergies. A study published in Clinical & Experimental Allergy found that children who were exposed to pets before the age of six months had fewer allergy-related conditions such as asthma, hay fever, eczema, and upper respiratory infections as they grew older. Another study found that babies who lived in homes with pets had fewer colds and ear infections during their first year of life than babies living in homes without pets.

Pets are also good for mom and dad. Dogs have been found to lower the risk of heart disease, stress, depression, and chronic pain.