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First trimester of pregnancy

Your first trimester begins the day you conceive and lasts until week 12. Because it can take a while to start noticing any pregnancy symptoms and to work out just how far along you are, most things worth mentioning start at week six. There's still plenty of time to get used to the news and think about what's to come in the next nine months, but at this stage you're bound to have lots more questions than answers about what to expect in early pregnancy.

By Mumsnet HQ | Last updated Mar 21, 2023

It's no secret that the first trimester can be a little trying. Between the tiredness, the sickness and the emotional rollercoaster (thanks, pregnancy hormones), many women find the first stage of pregnancy the toughest. But it does get easier – we promise – and in the meantime, there are plenty of amazing developments and changes taking place to keep your mind off the nausea/fatigue/heartburn (delete as appropriate). So, what happens during the first trimester?

How long is the first trimester?

Your first trimester begins at conception and ends at week 12. Since you're generally not aware you're pregnant for the first few weeks, as far as most women are concerned, the first trimester starts the moment you get that big, fat positive sign on the pregnancy test.

Your questions about the first trimester answered

First trimester symptoms

  • Morning sickness
  • Tiredness
  • Weird cravings
  • Headaches and migraines
  • Heartburn and indigestion
  • Bleeding gums
  • Constipation
  • Swollen feet and ankles
  • Back pain

Things to do in the first trimester

Thinking ahead to later in pregnancy

What Mumsnetters say about the first trimester…

"First of all, congrats! And welcome to the weirdest few weeks of your life. Eat well now, as you might not be able to for much longer. Take folic acid/a good prenatal vitamin. See a doctor or self-refer to midwives to get in the system. And then just take care of yourself. It can be a difficult time, lots of waiting and worrying and not feeling amazing."

"A lot of people find they have to eat regularly to stave off nausea and sickness, so get lots of healthy snacks in. It's obviously great to try and eat healthily, but if the only way to not be sick is to eat bread and sweets all day long then don't worry about it – anything to get through. Tiredness is also a common symptom, so batch cooking and freezing is also great for those days when you really don't have the energy. And you don't need to worry about pressure on your tummy too much. Until about 12 weeks, the baby is safely tucked behind the pelvic bone out of trouble."

"Eat as well as you can (subject to any sickness), but if you just fancy tea and toast, have it. You'll go through phases about what you do and don't want to eat and it will probably even out. Relax as much as you can – your body will tell you if you need to rest."

"I found it a real mental challenge getting through the first trimester. The worry can be crazy and while this never really goes away (so far, but I'm only 20 weeks with my first) I think the best thing for a reduced stress first baby/first trimester is to stay away from Dr Google. Good luck. It's an awesome journey!"

"It was a long 12 weeks for me…all I can suggest is to do gentle exercise (I went for long walks), eat well and try not to worry too much. I told my parents and one close friend, as it helped to be able to talk to someone about it, even if it's just to moan!"

"I can recommend ginger, Gaviscon and getting as much rest as you can. The second trimester is easier."