A full-term pregnancy allows the baby time to gain essential weight and to fully develop organs, but one in 10 infants in the US is born too early, weeks before they reach important developmental and fetal growth milestones. Premature birth occurs when a baby is born three weeks before the estimated due date. There are several reasons why some babies arrive too soon. Health communities have a much better understanding of the causes of premature births than they did a decade ago, and the number has steadily declined.


1. Preterm or Premature Babies

A full-term pregnancy is 40 weeks. Premature births are those that occur before the 37th week. These newborns are much smaller in size; while the median weight of a full-term baby is seven pounds, 14 ounces, a baby born at 35 weeks gestation weighs between two and three pounds less. Most preterm babies are born during the late preterm stage, between 34 and 36 weeks. Extremely preterm infants may be born at or before 25 weeks of pregnancy. However, they have a 90 percent chance of survival in developed countries thanks to modern technologies and specialized pediatric medical fields that focus on issues affecting premature infants.

preterm premature birth baby andresr / Getty Images

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