Plain-English guides to the questions that come up most during pregnancy.
Due dates are calculated by adding 280 days (40 weeks) to the first day of your last period, using Naegele's rule. See how it works and when ultrasound changes it.
Read →Your pregnancy week is counted from the first day of your last menstrual period. Learn how weeks are counted, what each stage means, and how to find your current week.
Read →Pregnancy is divided into three trimesters: weeks 1-13, 14-27, and 28-40. See what happens in each stage and what to expect at every milestone.
Read →Only about 4 to 5% of babies are born on their exact due date. Most arrive within a 2-week window. Learn why due dates are estimates, and how ultrasound affects accuracy.
Read →Your conception date is roughly 14 days after your last period in a 28-day cycle, or about 266 days before your due date. Use this guide and the calculator to estimate it.
Read →Full term is defined as 39 to 40 weeks of pregnancy. Births from 37 to 42 weeks are within the normal range. Early term is 37 to 38 weeks, and late term is 41 weeks.
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