Your Estimated Due Date

Pregnancy normally lasts between 37 and 42 weeks. You can roughly calculate your baby’s due date using the date of the first day of your last period. You can do this at:

Pregnancy due date calculator – NHS (

This will give you an estimated due date for your baby. Remember, it’s just a guess. Your baby might come a little earlier or later than the due date. Your due date may change after your baby is measured during your ultrasound scan (dating scan) at 10-14 weeks.

Pregnancy in often discussed as being split into “Trimesters”.

  • The first trimester begins on the first day of your last period and lasts until the end of week 12.
  • The second trimester is from week 13 to the end of week 26.
  • The third trimester is from week 27 to the end of the pregnancy.
Infographic showing the stages of pregnancy