Definition of Premature Birth
A premature birth is defined as babies born alive before 37 weeks of pregnancy are completed. There are sub-categories of preterm birth, based on gestational age:
- Extremely preterm (<28 weeks)
- Very preterm (28 to <32 weeks)
- Moderate to late preterm (32 to <37 weeks).
Small for gestational age (SGA):
Babies are those whose birth weight lies below the 10th percentile for that gestational age.
Low birth weight (LBW):
Is used to define a baby that weighs less than 5 lb 8 oz (2500 g) regardless of gestational age.
Very Low Birth Weight (VLBW):
Babies weigh less than 3 lb 5 oz (1500 g)
Extremely Low Birth Weight (ELBW):
Babies weigh less than 2 lb 3 oz (1000 g).
Survival Rates (approx.)
Babies born at 23 weeks have a 29% chance of survival (50% of them have no disability at age 3).
Babies born at 24 weeks have a 46% chance of survival (60% of them have no disability at age 3).
Babies born at 25 weeks have a 69% chance of survival (70% of them have no disability at age 3).
Babies born at 26 weeks have a 78% chance of survival (80% of them have no disability at age 3).
Babies born at 27 weeks have a 90% chance of survival.
Babies born between 28-31 weeks gestation have at 90-95% chance of survival.
Babies born between 32-33 weeks have a 95% chance of survival.
Most babies born 34 weeks onwards have the same likelihood of survival as a full term infant.
Rate of Preterm Birth
Globally over 15 million infants are born too early, too small and too sick each year: that’s one in 10 babies. Here in Ireland the figure stands around 4,500 and that equates to one baby born prematurely every 116 minutes. Despite the high number of preterm births in the world, there is little known about prevention of preterm delivery and the problems and risks for the development of preterm babies so far.