That was a group B strep culture. It's to screen your for the presence of a type of strep bacteria in your vagina. Some women carry this bacteria all their lives with no ill effects. But when the baby passes through your vagina, the bacteria can infect the eyes, ears, or upper respiratory system, which can lead to serious complications in a newborn. Moms who test positive for group B strep are usually given a fairly large dose of penicillin when they come to the hospital to deliver, which kills off the bacteria long enough to safeguard the baby.
You will need to know whether you are group B positive or negative, in case you go into labor unexpectedly. This is something they will ask you at the hospital.
