Though there is a slight increase in infant mortality rates for babies born at 37 weeks compared to babies born at 40 weeks, most babies born at 37 weeks do well, explains WebMD. If labor starts naturally after 37 weeks, doctors usually allow it to continue.
Studies on babies' development during the last weeks of pregnancy show that risks decrease as the pregnancy nears 41 weeks and begin to increase again at 42 weeks, states WebMD. Babies' brains, lungs and other organs continue to grow and develop between 37 and 40 weeks. Women who seek elective delivery should wait until 39 weeks to reduce health risks to their babies.