Labor beginning before the 37th or 38th week of gestation or before the fetus has reached a weight of 2,000 grams. Premature labor may occur spontaneously without apparent cause, or it may result mom trauma, chronic disease, infection in the mother, placental problems, or other causes; predisposing factors are poor nutrition, low weight gain, smoking, and multiple pregnancies. In some cases labor can be inhibited and the pregnancy prolonged to allow further development of the fetus.
Labor that begins after the 28th week but before the 40th week of pregnancy is considered preterm. From the 28th week onwards, there is a possibility, albeit slight, that the baby will survive outside the womb. However, if labor commences before the 28th week, the baby’s chances of survival are minimal, and this event is typically termed a miscarriage or spontaneous abortion.