Group B strep is a bacteria that can come and go naturally in your body, but which can be detrimental to your baby if you are not treated. An antiobiotic can be given to a woman while she is in labor but not before. Check with your doctor and request a GBS test when you are 35-37 weeks pregnant. The test is described as an "easy swab of the vagina and rectum"......check out the CDC site for further info.