Question 1

How do I calculate my pregnancy week from my due date?

Accepted Answer

To calculate your pregnancy week from your due date (EDD), subtract 280 days from your EDD to find your Last Menstrual Period (LMP). Then count the weeks from your LMP to today's date. For example, if your EDD is 40 weeks away, you're at week 0; if it's 20 weeks away, you're at week 20. Our calculator does this automatically and shows your exact week and days.

Question 2

Why does my doctor use EDD from ultrasound instead of LMP?

Accepted Answer

Ultrasound dating, especially in the first trimester (NT scan at 11-14 weeks), is more accurate than LMP-based calculations. LMP assumes a 28-day cycle with ovulation on day 14, but many women have irregular cycles. Ultrasound measures the baby directly, providing accuracy within 5-7 days in the first trimester, compared to up to 2 weeks variance with LMP dating.

Question 3

What is gestational age vs fetal age?

Accepted Answer

Gestational age is counted from the first day of your last menstrual period (LMP), which is typically 2 weeks before conception. Fetal age (also called embryonic age) is the actual age of your baby from conception. So at 10 weeks gestational age, your baby's fetal age is approximately 8 weeks. Medical professionals use gestational age for pregnancy tracking and due date calculations.

Question 4

How accurate is a due date from NT scan?

Accepted Answer

The NT (Nuchal Translucency) scan, performed between 11-14 weeks, provides highly accurate dating with a margin of error of only 5-7 days. This is more accurate than second or third trimester ultrasounds, which have larger margins of error. If your NT scan date differs from your LMP-based date by more than 5-7 days, most doctors will adjust your EDD to match the ultrasound.

Question 5

What trimester am I in based on my pregnancy week?

Accepted Answer

First trimester: Weeks 1-12 (conception through 12 weeks). Second trimester: Weeks 13-27 (development and growth phase). Third trimester: Weeks 28-40+ (final growth and preparation for birth). Each trimester has different milestones, symptoms, and medical checkpoints. Our calculator automatically shows your current trimester and remaining weeks.

Question 6

Can my due date change during pregnancy?

Accepted Answer

Yes, your due date may be adjusted, usually after a first-trimester ultrasound. If the ultrasound-based gestational age differs from LMP-based age by more than 7 days, doctors typically update the EDD. However, once established in the first trimester, the EDD generally shouldn't change based on later ultrasounds, as these are less accurate for dating.

Question 7

What percentage of babies are born on their due date?

Accepted Answer

Only about 4-5% of babies are born exactly on their due date. Most babies (80%) arrive between 38 and 42 weeks. Your due date is an estimate, not a deadline. Full-term is considered 39-40 weeks, early term is 37-38 weeks, and late term is 41-42 weeks. Post-term pregnancy begins after 42 weeks.

Question 8

How do I calculate my conception date from EDD?

Accepted Answer

To calculate your conception date from EDD, subtract 266 days from your due date (EDD - 266 = conception date). This is because pregnancy is counted as 280 days (40 weeks) from LMP, but conception typically occurs 14 days after LMP. Our calculator automatically shows your estimated conception date when you enter your EDD.

Pregnancy Week Calculator — Find Your Current Week from EDD

Understanding Your Pregnancy Timeline

First Trimester

Second Trimester

Third Trimester

Key Pregnancy Milestones

Week 6-7

Week 11-14

Week 18-22

Week 24

Week 28

Week 37-40

Frequently Asked Questions

Medical Review & Sources

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