Like many women pregnant for the first time, I looked forward to every doctor's appointment with a mix of excitement and trepidation. Having the chance to hear my son's heartbeat filled my own heart with joy, and finding out how he was developing made the reality that I was about to become a mother feel even more concrete. At the same time, I worried that a routine visit would reveal a health problem with my son. As each appointment passed without concern, however, I started to relax, and I entered my last month of pregnancy feeling more ready than worried.
Then came the appointment when my doctor performed the routine screening for group B strep—and the results came back positive. My doctor immediately reassured me that this infection was both common and easy to treat. She was right, of course; about 25 percent of healthy, adult women have this bacteria, and the treatment to protect a baby from becoming infected during birth—intravenous antibiotics during delivery—is simple to administer and highly effective.
What my doctor didn't mention, however, was that these antibiotics would naturally wipe out not only the Group B strep bacteria but also the good bacteria. I spent the remaining weeks of my pregnancy reading up on the potential effects of a group B strep infection on my newborn son; little did I know that my real concern should have been the effect that the antibiotics would have on my son's ability to build one of his greatest lifelong defenses against illness: a strong microbiome.