Dr. Anna Zimmerman is a neonatologist in Denver and says pre-term births happen and they are not the fault of moms. She says the conception in the U.S. is you get pregnant and you are going to have a healthy baby. Most of the time it goes that way for more than 90% of mothers. A pre-term baby is one that is born before 37 weeks. Babies born from 22 weeks up until 26 weeks are considered extremely preterm deliveries.