Pregnancy Week-by-Week
Track your pregnancy week by week. Enter the first day of your last period to see your current gestational week, your trimester, and a short note on what’s developing now.
Pregnancy Week-by-Week
Track your pregnancy week by week. Enter the first day of your last period to see your current gestational week, your trimester, and a short note on what’s developing now.
Informational only — not medical advice or a diagnosis. Every pregnancy and cycle is different, and these results are estimates. Always consult your OB-GYN or midwife.
Gestational age is counted from the first day of your last period.
Enter your dates above to see your result.
This is an educational estimate, not medical advice. Consult a qualified professional. For pregnancy and cycle decisions, follow your OB-GYN — guidance reflects the American College of Obstetricians and Gynecologists (ACOG).
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How pregnancy weeks are counted
Gestational age is counted from the first day of your last menstrual period (LMP) — not from conception. That means you are considered about two weeks "pregnant" before conception actually happens, which is why a 40-week pregnancy reflects roughly 38 weeks of fetal development.
This calculator works out how many weeks and days have passed since your LMP and shows the developmental milestone typical for that week, from the first heartbeat in early weeks to the rapid brain growth of the third trimester.
The three trimesters
The first trimester (weeks 1–13) is when all the major organs form — a period of rapid, delicate development. The second trimester (weeks 14–27) is often the most comfortable, when many people first feel movement and learn the sex if they wish. The third trimester (weeks 28–40) is mainly growth and maturation, especially of the lungs and brain.
Each week brings change, but development is a continuum: the notes here describe what is typical, and healthy babies vary in size and timing.
Using the milestones
The weekly notes are a friendly guide to what’s generally happening, not a checklist your baby must match. Your routine antenatal appointments, blood tests and scans are what actually confirm that your pregnancy is progressing well.
If you ever notice reduced movements, bleeding, severe pain or other worrying symptoms, contact your maternity team straight away rather than waiting for your next appointment.
Frequently asked questions
Why is pregnancy counted from the last period?
Counting from the last menstrual period gives a consistent starting point that everyone can identify, even though conception happens about two weeks later. It is the standard clinicians use.
How many weeks is a full-term pregnancy?
Full term is 39–40 weeks, and birth any time from 37 to 42 weeks is considered normal. Your due date marks the end of week 40.
Are the weekly milestones exact?
No. They describe what typically develops each week, but healthy babies vary in size and timing. Your scans and appointments confirm how your own pregnancy is progressing.
Sources & references
Not medical advice. This result is an educational estimate from HealthyLifeStyles (Trusted Wellness), based on population formulas — not a diagnosis or treatment. Always consult a qualified healthcare professional about your health.
https://www.healthylifestyles.com/tools/pregnancy-week-calculator