how many weeks pregnant

The number of weeks pregnant is typically calculated from the first day of the last menstrual period (LMP). Pregnancy normally lasts from about 37 to 42 weeks, with an average duration of approximately 40 weeks or 280 days. The counting starts with Week 0 on the first day of the last period and continues until the estimated due date (EDD), which is usually 40 weeks later. Pregnancy week counting can also be adjusted if the conception date or early ultrasound scans are known, which can provide a more accurate estimate. Healthcare providers often offer a 12-week scan to better estimate the exact number of weeks pregnant. In summary, how many weeks pregnant someone is calculated by counting the number of weeks since the first day of their last menstrual period, with the typical pregnancy length being about 40 weeks.