When babies come into this world, they are exposed to bacteria for the very first time.

But not all bacteria is bad. In fact, some can keep babies healthy and prevent sickness in the future.

As a baby grows inside the womb, he gets almost everything from the mother, but what he picks up on the way out can be just as important.

“When a baby is delivered vaginally going through the birth canal, they actually get populated on their skin with that mom's flora, the bacteria that live in mom’s body,” explains Dr. Elizabeth Meade, Assistant Chief of Pediatrics at Swedish Medical Center.

The bacteria collects in the baby's gut and creates what is called the microbiome - an army of bacteria living in our bodies that protect us from birth. Meade says new studies enforce the importance of bacteria sharing between moms and babies.

“There is some research now that suggests any disruption in that diversity of that bacteria early on in life can have a negative effect later, one of them being a higher likelihood of developing allergies and asthma,” says Meade.

One of those studies was led by a gastroenterologist at the University of California, San Francisco.

Researchers tracked 298 children from birth, looking at the different types of bacteria in their stool at one month old. They found that those with the lowest amounts were more likely to show signs of allergy by their second birthday.

“The more of that you are exposed to then potentially the healthier or stronger immune system you have,” says Meade.

Another way to fill your baby's belly with all that good bacteria? When they drop their pacifier, pop it in your mouth to clean it. What about cesarean-born babies who do not pass through the birth canal? Doctors are looking at ways they can spread that biodiverse bacteria by hand.

“They are actually putting a piece of sterile gauze inside the mom's vagina about an hour before the baby is born, and when the baby comes out they are swabbing the babies skin with a piece of gauze,” describes Meade.

While that may not be standard of care just yet, Meade also says breastfeeding and keeping a dog in the home can help baby build up all that beneficial bacteria.