Educational content, not medical advice. Clinical review of this page is in progress.
Quick answers to the questions people ask most often about gestational age.
Related Reading
- Traditional vs. IVF Dating — how the starting point changes
- When Gestational Age Gets Adjusted — why a due date can change
- Due Date Calculator — estimate when your baby may arrive
- Due Date Guide — how due dates work
Also see our calculator FAQs, pregnancy FAQs and pregnancy terms glossary.
Frequently Asked Questions
Why does gestational age start before conception?
Because it’s counted from your last menstrual period, roughly two weeks before ovulation typically occurs, not from the moment of conception.
How many weeks is full term?
Full term is 39 weeks 0 days through 40 weeks 6 days gestational age.
Can two people with the same LMP have different due dates?
Yes, if ultrasound measurements or known conception dates lead a provider to adjust one person’s dates but not the other’s.
Is gestational age the same worldwide?
Yes, gestational age (counted from LMP) is the international clinical standard, even though everyday conversations sometimes use fetal age informally.
How is gestational age different from how many weeks since conception
Gestational age counts from the first day of your last menstrual period, so it runs about two weeks ahead of the time since conception. See Gestational Age vs. Fetal Age.
How long is a full-term pregnancy
A pregnancy is about 40 weeks of gestational age. Births from 39 weeks 0 days to 40 weeks 6 days are considered full term; earlier or later timing has its own terms, which your provider can explain.
Why did my ultrasound give a different due date
Early ultrasound measurements can be more precise than a remembered last-period date, especially with irregular cycles. Providers may adjust the date if the difference is large enough. Read When and Why Gestational Age Gets Adjusted.
Is my calculator result my exact due date
No. Only a small share of babies arrive on the estimated due date. Use the result as a planning guide with the Due Date Calculator and confirm dating with your provider.
How is gestational age calculated after IVF
IVF dating uses the embryo transfer date and embryo age, which is more exact than counting from a last period. See our IVF Due Date Calculator.
Where can I check my week-by-week milestones
Our guide to pregnancy milestones by gestational age and the Pregnancy Week by Week tool are good starting points.
Related Resources
Sources and Further Reading
This page is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your OB-GYN or midwife about your own pregnancy.