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).

 

Table showing 'Preterm Birth Weight' for Boys on the left and girls on the right. Gestation periods are listed bi weekly from 24 - 36 Weeks with corresponding weights in Grams and Lbs.

 

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 13.4 million infants are born too early, too small and too sick each year: that’s one in 10 babies.  Here in Ireland the figure  is approx.  3,500.  The following is an overview of the number of annual births and preterm births in Ireland for the past 5 years.

YEAR               BIRTHS          PREMATURE BIRTHS             %

2022                54,467

2021                60,804                       3,587                              6.9%

2020               57,064                        3,982                              7.0%

2019               59,084                        3,657                               6.2%

2018               60,744                         3,600                              5.9%