The first trimester starts on the first day of the previous menstrual period you had, which means by the time you realise that you are definitely pregnant you will most likely be more than 4 weeks pregnant.
The first trimester is a time of intense activity and the baby will experience its fastest rate of growth during this period. By the end of your first trimester, (13 weeks) your baby will roughly be the size of your little finger.
This busy period of development for the baby can be a tiring stage of pregnancy for the mum-to-be. Often the nausea, tiredness and emotions of this first trimester can take a woman by surprise, particularly as you don't actually look pregnant yet, but it is perfectly normal. For most women, the difficult side effects of the first trimester tend to subside towards the end of the first 13 weeks, although for some it can take a little longer.
- Fertilization and the start of your baby's life
- 4 weeks in to your first trimester
- 5 weeks in to your first trimester
- 6 weeks in to your first trimester
- 7 weeks in to your first trimester
- 8 weeks in to your first trimester
- 9 weeks in to your first trimester
- 10 weeks in to your first trimester
- 11 weeks in to your first trimester
- 12 weeks in to your first trimester
- 13 weeks in to your first trimester
Changes you should be making:
Being pregnant is a big responsibility. It is important that you do everything you can to look after yourself and your baby during your pregnancy. There are a lot of things you can easily change in your lifestyle in order to maximise your chances of a healthy pregnancy and you should make these changes as early as possible. Take a look at our do's and don'ts of pregnancy section to see what you can and can't do when it comes to food, drink, pets, jacuzzis and more.
Make sure that you are keeping on top of what happens during pregnancy week by week because there is a lot to take in!
We have listed your trimester week by week so you can see what exactly you and your baby should be going through.