Antibiotics taken late in pregnancy can increase risk for inflammatory bowel diseases in offspring. When mice that are genetically susceptible to developing inflammatory bowel disease (IBD) were given antibiotics during late pregnancy and the early nursing period, their offspring were more likely to develop an inflammatory condition of the colon that resembles human IBD, report scientists. Source 1h.
I would be apprehensive about taking anything during pregnancy that may affect the embryo or fetus because you can't know how it might affect you. No matter how many studies are done there is always that small percentage risk of something going awry.