What is considered preterm?
The duration of pregnancy is calculated from the first day of your last menstrual period. Your due date is calculated as being 40 weeks from your last period, but every delivery occurring beyond the 37th week is considered full term. To understand what preterm is, it is necessary to divide the pregnancy into three stages: first state, from the first day of the last menstrual period to the 19th week; second state, from the 20th to the 36th week; and third state, from the 37th to the 40th week of pregnancy. If pregnancy ends prior to 20 weeks of gestation, it is considered miscarriage or an abortion (spontaneous or therapeutic). If pregnancy ends after the 20th week, it is considered delivery. If the delivery occurs during the period from 20 to 36 weeks, it is a preterm birth. If delivery occurs at or beyond 37 weeks of pregnancy, it is a term birth.