Pregnancy Calculator & Due Date Estimator
Our Pregnancy Calculator is the first step on your incredible journey. Use this tool to get an accurate estimate of your due date and a personalized pregnancy timeline. Discover key milestones, track fetal development, and prepare for parenthood with confidence.
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Understanding Your Pregnancy Journey: A Week-by-Week Guide
A typical pregnancy lasts about 40 weeks from your last menstrual period (LMP). This pregnancy timeline is divided into three trimesters, each marking significant steps in fetal development and changes in your body.
The Three Trimesters of Pregnancy
First Trimester (Weeks 1-13): The Foundation
This critical period is when your baby's foundational structures are formed. While you may just be discovering you're pregnant, incredible development is already underway.
- Baby's Development: The brain, spinal cord, and heart begin to form. By the end of this trimester, all major organs are developing, and tiny fingers and toes have appeared.
- Common Symptoms for Mom: You may experience early signs of pregnancy such as fatigue, morning sickness, breast tenderness, and frequent urination as your hormones shift.
Second Trimester (Weeks 14-27): The Golden Period
Often the most comfortable trimester, this is a time of rapid growth and exciting milestones for both you and your baby.
- Baby's Development: Your baby's senses—hearing, sight, and touch—are developing. They can now swallow and may even respond to external sounds. You'll likely feel their first movements, known as "quickening."
- Common Symptoms for Mom: Nausea and fatigue may decrease, replaced by a growing baby bump, increased energy, and possibly some backaches or round ligament pain.
Third Trimester (Weeks 28-40+): The Final Stretch
In this final phase, your baby matures and prepares for birth, and your body gets ready for labor and delivery.
- Baby's Development: The baby gains weight rapidly, and their lungs and brain continue to mature. They will settle into a head-down position in preparation for birth.
- Common Symptoms for Mom: You may experience shortness of breath, heartburn, and Braxton Hicks contractions. Your prenatal care schedule will become more frequent.
How Is My Due Date Calculated?
While only about 5% of babies are born on their exact due date, an estimated date is crucial for monitoring your baby's health. Our calculator uses several methods to provide the most accurate estimate.
Last Menstrual Period (LMP) Method
This is the most common method for calculating your due date, based on Naegele's rule.
- How it works: We add 280 days (40 weeks) to the first day of your last period.
- Best for: Individuals with a regular, 28-day menstrual cycle.
Conception Date Method
If you know the exact date of conception, this method can be more precise.
- How it works: We add 266 days (38 weeks) to your known conception date.
- Best for: Those who tracked ovulation or used fertility treatments like IVF.
Ultrasound Dating Method
An early pregnancy ultrasound is considered the most accurate way to determine a due date.
- How it works: A doctor measures the baby's size (crown-rump length) to determine the precise gestational age.
- Best for: Everyone, especially those with irregular cycles or an unknown LMP.
Next Steps: What to Do After a Positive Pregnancy Test
Seeing that positive result is an unforgettable moment. Here are the first steps to take on your new journey:
- Schedule Your First Prenatal Appointment: Call your doctor or midwife to confirm the pregnancy and establish a prenatal care schedule. This is the most important first step for a healthy pregnancy.
- Start Taking a Prenatal Vitamin: If you haven't already, begin taking a daily prenatal vitamin containing at least 400 micrograms (mcg) of folic acid to support your baby's neural tube development.
- Review Your Lifestyle: Evaluate your diet, exercise, and daily habits. It's time to avoid alcohol, smoking, and certain foods, and to discuss any medications you're taking with your doctor.
- Rest and Hydrate: Your body is working hard. Prioritize getting enough sleep and drinking plenty of water throughout the day.