Pregnancy is typically measured as 40 weeks long, starting from the first day of the woman's last menstrual period (LMP) to the estimated due date. This 40-week period is divided into three trimesters:

• First trimester: Weeks 1 to 12
• Second trimester: Weeks 13 to 26
• Third trimester: Weeks 27 to 40

It's important to note that a full-term pregnancy can range from about 37 to 42 weeks. Babies born before 37 weeks are considered preterm, and those born after 42 weeks are post-term. If you want, I can help you calculate the estimated due date based on a specific date!