An infant born before 36 weeks gestation is premature. Anatomic structures are all present, but with decreased lung maturity, decreased body fat, poor postural control, underdeveloped fat pads (sucking pads), and underdeveloped sensorimotor systems. These infants may have difficulty coordinating suck, swallow, and breathing. Extreme prematurity is less than 28 weeks gestation. Survival at 23 weeks gestation is possible, but infants are usually not ready to feed orally until 31 or 32 weeks at the earliest, often closer to 34 weeks gestation, and some up to 37 weeks.