Premature births still a medical mystery

While recent medical advancements mean most preemies will survive, preventing early birth in the first place is a different story. Doctors have no way of knowing which pregnancies will be preterm, and in about half of all cases, they don’t know why a mother delivers early. However, science is beginning to divulge some clues, such as social stress, bacterial infection and hereditary influences, which might be tied to early births.