<P> There is no sharp limit of development , gestational age , or weight at which a human fetus automatically becomes viable . According to studies between 2003 and 2005 , 20 to 35 percent of babies born at 23 weeks of gestation survive , while 50 to 70 percent of babies born at 24 to 25 weeks , and more than 90 percent born at 26 to 27 weeks , survive . It is rare for a baby weighing less than 500 g ( 17.6 ounces ) to survive . A baby 's chances for survival increase 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 . </P>
<P> There is no sharp limit of development , gestational age , or weight at which a human fetus automatically becomes viable . According to studies between 2003 and 2005 , 20 to 35 percent of babies born at 23 weeks of gestation survive , while 50 to 70 percent of babies born at 24 to 25 weeks , and more than 90 percent born at 26 to 27 weeks , survive . It is rare for a baby weighing less than 500 g ( 17.6 ounces ) to survive . A baby 's chances for survival increase 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 . </P>
percentage of babies born at 24 weeks that survive
percentage of babies born at 24 weeks that survive
50 to 70 percent
50 to 70 percent