Pregnancy trimesters: a gentle overview

Pregnancy is counted from the first day of your last period, not from the day the egg meets the sperm. So by the time you get a positive test you might already be “4 weeks pregnant”. Yes, it is confusing. Everyone thinks so.

It is split into three trimesters. Every pregnancy is different, so think of this as a rough map, not a checklist. Your due date is an estimate, and plenty of healthy babies arrive before or after it.

First trimester (up to week 12)

Huge changes happen quietly. Early signs usually start around 4 to 6 weeks: tiredness, feeling sick, sore breasts and needing to pee more. Your first midwife (booking) appointment is usually at 8 to 12 weeks, and the dating scan at 11 to 14 weeks. Folic acid is advised until week 12.

Second trimester (weeks 13 to 27)

The NHS describes this as the stage when you are hopefully past the worst of early symptoms. Most people first feel their baby move somewhere between 16 and 24 weeks. The mid-pregnancy scan is at 18 to 21 weeks, and the whooping cough jab is offered from 16 weeks.

Third trimester (week 28 to birth)

Your bump grows fast. Backache, heartburn, tiredness and poor sleep are common. This is the time to plan for birth and feeding, and to learn the signs of labour. The RSV jab is offered from 28 weeks. In later pregnancy, avoid lying flat on your back for more than a few minutes, as it can make you dizzy.