Pregnancy Due Date Calculator
Enter the first day of your last menstrual period to estimate your due date, current gestational age, and key pregnancy milestones.
Understanding Your Due Date
How Are Due Dates Calculated?
Due dates are most commonly estimated using Naegele's rule, which adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This method assumes a regular 28-day cycle with ovulation occurring on day 14. While this calculation has been the standard for over 200 years, it is an estimate. Only about 5% of babies are born on their exact due date. Most babies arrive within two weeks before or after the estimated date. Your healthcare provider may adjust your due date based on early ultrasound measurements, which can be more accurate for women with irregular cycles.
The Three Trimesters of Pregnancy
Pregnancy is divided into three trimesters, each spanning roughly 13 weeks: First trimester (weeks 1-12): The baby's major organs begin to form. You may experience morning sickness, fatigue, and breast tenderness. This is the most critical period for development. Second trimester (weeks 13-26): Often called the "golden period," many women feel their best during these weeks. The baby begins to move, and you may start to show. Key anatomy scans are done during this time. Third trimester (weeks 27-40): The baby gains weight rapidly and organs mature. You may experience back pain, difficulty sleeping, and Braxton Hicks contractions as your body prepares for delivery.
What to Expect as Your Due Date Approaches
As you near your due date, your body will begin preparing for labor. You may notice signs like "lightening" (the baby dropping lower into the pelvis), increased Braxton Hicks contractions, and changes in your cervix. A full-term pregnancy is considered 39-40 weeks. Babies born between 37-38 weeks are "early term," while those born at 41+ weeks are "late term." Your provider will discuss induction options if you go past your due date. Tracking your pregnancy milestones and symptoms with an app like Cyla can help you stay informed and share accurate information with your healthcare team.
Frequently Asked Questions
Track Your Pregnancy Journey
Cyla helps you monitor your cycle, predict fertile windows, and understand your body. Free to download.
