Preterm Birth. Reasons and Risks
November is prematurity awareness month, and I felt the need to shed the light on its importance from an obstetric instead of a neonatal point of view, but before talking about preterm births, let us define a “full term pregnancy”. A full term pregnancy means a pregnancy ending at or after 40 weeks of gestation, and this number is calculated from a preset due date. But how is this date even set? In the setting of a spontaneous pregnancy, a due date is either calculated from the date of last menstrual period (using Naegele’s formula) or based on the baby’s measurements on ultrasound during early pregnancy. The latter method is becoming the norm now (especially in eminent centers around the world), because the date of the last menstrual period is not helpful in dating a pregnancy in women with late ovulations or irregular cycles. In the setting of a pregnancy following in vitro fertilization, the dating depends on the embryo transfer date and the age of the embryo at the time of the t...