When is the earliest my baby can be born without being "premature? "

37 weeks. But you cannot round up! neonatologists have taught us that every day counts for a premature baby. So most consider preterm birth to occur before 37 "completed" weeks. Many perinatologists evaluate in terms of those extra days also. Expectant parents can consider a baby term when it is born 259 days from day 1 of last normal menstrual period or 245 days after conception spontaneously or by ivf.
37 weeks. Babies born after 37 weeks are considered term. A baby born before 37 weeks will be considered premature/preterm.