Preterm labor

Preterm birth is defined as the birth of a baby at less than 37 weeks of gestational age. The earlier a baby is born, the greater the risk, variety, and severity of complications to the infant's health, particularly to the respiratory system. The earliest gestational age at which a baby has at least a 50% chance of survival is approximately 24 weeks. Signs of preterm labor include frequent and painful uterine contractions, vaginal bleeding, cramping, and lower back pain.