Pregnancy Week by Week: Trimesters, Scans and Key Dates
Updated: 2026-11-09
This overview shows what usually happens in each stage of pregnancy and when common appointments take place. Schedules vary by country and by individual, so always follow your own midwife or doctor.
How weeks are counted
Pregnancy is counted from the first day of your last period, so conception usually happens around week 2. A full pregnancy is about 40 weeks. Work out your dates with the due date calculator.
First trimester (weeks 1–13)
- Weeks 4–5: a home pregnancy test can show positive around the time of a missed period.
- Weeks 6–8: tiredness, nausea and breast tenderness are common. Many women book their first antenatal appointment.
- Weeks 10–14: the dating scan confirms how far along you are and often includes screening tests offered in your country.
- Health services recommend taking folic acid (400 micrograms a day) from before conception until week 12.
Second trimester (weeks 14–27)
- Nausea often eases and energy returns.
- Weeks 18–21: the anomaly or anatomy scan checks the baby's development.
- Around weeks 16–24: many women first feel the baby move.
- Weeks 24–28: a glucose test for gestational diabetes may be offered.
Third trimester (week 28 to birth)
- More frequent check-ups to monitor growth, blood pressure and the baby's position.
- Week 37: the baby is considered full term (early term until 39 weeks).
- Week 40: the estimated due date. Only a small share of babies arrive that day.
- Weeks 41–42: your care team will usually discuss options such as induction.
When to call your midwife or doctor urgently
Seek help straight away for vaginal bleeding, severe abdominal pain, severe headache or vision changes, sudden swelling of the face or hands, fluid leaking from the vagina, a change in or loss of the baby's movements, or fever. In an emergency, call your local emergency number.
Sources: NHS, "Your pregnancy and baby guide"; ACOG, "Definition of Term Pregnancy" (Committee Opinion 579); WHO recommendations on antenatal care for a positive pregnancy experience (2016).
Guides
These tools give general information, not medical advice. Talk to a doctor about your health. See our medical disclaimer.