There are many factors which will determine the preemies chances for survival.  Here are just a few very important factors:

	Gestational age at birth (number of completed weeks of pregnancy)
	The weight of the baby
	Indications of breathing problems or not
	The presence or absence of congenital abnormalities or malformations
	The presence of any severe diseases, especially infection

Nanelle born 26w holding dad hand when she is a couple of days old

Gestational age is usually most important because it determines if the infant's organs, particularly the lungs, have developed enough to allow the baby to live within the limits of current technology. 

Your baby's doctor will be able to give you the best estimate of your infant's chances since he/she can take into consideration many of the above factors. 

...But, no estimate is perfect. Some babies suddenly get sick and die unexpectedly; others defy all odds. General estimates of survival for live born infants who receive neonatal intensive care in the USA in the late1990's are:

* Most babies at 22 weeks are not resuscitated because survival without major disability is so rare.

A baby's chances for survival increases 3-4% per day between 23 and 24 weeks of gestation and about 2-3% per day between 24 and 26 weeks of gestation. After 26 weeks the rate of survival increases at a much slower rate because survival is high already.

What other factors influence survival?

Other factors may influence survival by altering the rate of organ maturation or by changing the supply of oxygen to the developing fetus.

	Rupture of the fetal membranes before 24 weeks of gestation with loss of amniotic fluid markedly decreases the baby's chances of survival even if the baby is delivered much later.
	Male infants are slightly less mature and have a slightly higher risk of dying than female infants.
	For a given weight, African-American babies have a slightly better survival than Caucasian; most other races are intermediate between the two
	Diabetes in the mother, if not well controlled, slows organ maturation and these infants have a higher mortality.
	Severe high blood pressure before the 8th month of pregnancy may cause changes in the placenta, decreasing the delivery of nutrients and/or oxygen to the developing fetus and leading to problems before and after delivery.