Pregnancy Timeline by Due Date
Enter your due date or the first day of your last period to generate estimated trimester dates, scan windows, and practical UK planning milestones.
This page is for general pregnancy planning and date guidance only. It is not medical advice, diagnosis, or treatment. Pregnancy dates are estimates and can change after a scan or advice from your midwife, GP, or maternity team.
If you have symptoms, concerns, or questions about your pregnancy, speak to your midwife, GP, or maternity team. For urgent help, use NHS 111; call 999 in an emergency. Read how we source and review content in our editorial policy.
Build your pregnancy timeline
Use the date you already know to see estimated trimester dates, scan windows, and practical UK planning milestones.
Your UK Pregnancy Timeline
Your pregnancy is divided into three trimesters. Each phase brings different developmental milestones for your baby and physical changes for you.
- First Trimester (Weeks 1-12): Early development and the dating scan.
- Second Trimester (Weeks 13-27): Often called the "honeymoon period", this includes your 20-week anomaly scan.
- Third Trimester (Weeks 28-40+): Final growth stages and preparation for birth.
Maternity Planning Reminders
In the UK, you should receive your MATB1 certificate from your midwife or doctor around week 20 of your pregnancy. You must tell your employer about your pregnancy and the date you want to start your Statutory Maternity Leave at least 15 weeks before the beginning of the week your baby is due.
Sources and further reading
Checked for UK pregnancy timeline planning guidance in July 2026.
We prioritise official NHS and GOV.UK guidance, then relevant professional-body information where needed.
Source links are checked on the review date shown above. Your midwife, GP, maternity team, fertility clinic, or employer can give advice that is more specific to your circumstances.