At 1-4 weeks pregnant, it’s very early days. However, that doesn’t mean there isn’t plenty going on! Your body is working hard, and getting ready to support your growing baby during your first trimester and your entire pregnancy. 

From what’s going on in week 1 and 2 to spotting the signs of pregnancy in week 4, let’s take a look at those first few weeks.  

There’s a lot going on when you’re 1-2 weeks pregnant. In the first days after fertilisation, your fertilised egg divides rapidly, planting itself into the wall of your uterus, where it becomes an embryo¹. 

At 4 weeks pregnant, your baby is protected by an amniotic sac². For now, it gets all the nourishment it needs from a tiny ‘yolk sac’. This will eventually develop into your placenta, which will take over the vital job of providing your growing baby with oxygen and nutrients.

Your baby isn’t technically a foetus at 4 weeks – it’s still an embryo. You probably won’t hear your healthcare professionals calling your baby a foetus until you’re around 8 weeks pregnant³.

At 4 weeks pregnant, your little embryo is about the size of a poppy seed at only 2mm long². However, your baby is growing quickly inside your womb and is changing and developing at a rapid rate.

It’s unlikely that you’ll look pregnant at this stage, especially if you’re a first-time mum. In fact, you probably won’t start showing until around week 12². Your bump might show a little sooner if you've been pregnant before.

You might not ‘feel’ pregnant at week 4 of pregnancy either, but that’s likely to change once the pregnancy hormone human chorionic gonadotrophin (hCG) starts to build up and work its way around your body².

At this point in your pregnancy, you’re also starting to grow a whole new organ – your placenta – which won’t be fully formed for another few weeks². The placenta’s job is to pass oxygen, nutrients and antibodies to your baby to help them grow and develop throughout pregnancy, and will also produce hormones like hCG⁴.

Most women don’t notice the signs of pregnancy in week 4. A missed period is one of the most obvious tell-tale signs, and if your period doesn’t arrive, you might want to take a pregnancy test².

When it comes to the symptoms and signs of pregnancy at week 4, you might notice²:

• A metallic taste in your mouth
• Sore or tender breasts
• Nausea (also known as morning sickness)
• Feeling more tired than usual
• Changes in your taste and sense of smell
• Needing to pee more than usual
• Light spotting (usually around 1-2 weeks pregnant as the fertilised egg attaches to your uterus wall)
• Milky white vaginal discharge
• Cramps that might feel like period pains
• Bloating (due to an increase in progesterone that relaxes the digestive muscles)
• Thicker, shinier hair - everybody loves a good hair day!
• Patches of darker skin on your face (also called cloasma faciei or ‘the mask of pregnancy’)

Remember, every person and every pregnancy is different. At 4 weeks pregnant, symptoms that you notice (or don’t notice!) will likely be different to other people you know who have been pregnant before.

The best way to check whether you’re pregnant is to take an at-home pregnancy test. Some can tell you whether you’re pregnant as early as 3 and a half weeks with up to 99% accuracy.²

Here are some things you can do if you think you might be around 4 weeks pregnant.

If your at-home pregnancy test is positive, it’s time to book an appointment with your GP⁵. They’ll be able to confirm that you’re pregnant and help you work out your due date. In the meantime, why not try our due date calculator?

They can also give you some advice about folic acid supplements, vitamins and nutrition and talk to you about booking your first midwife appointment (also called a booking appointment).

You’ll need to start taking some prenatal vitamins, to help you and your baby stay healthy during your pregnancy.

Start by taking a folic acid supplement every day from now until week 12. Folic acid supports your baby’s developing nervous system and can help protect against conditions like spina bifida².

You should also vitamin D supplement throughout your entire pregnancy to help keep your bones and muscles healthy². If you have darker skin (if you're ethnicity is African, African Caribbean or south Asian, for example), you may be advised to take a higher dose of vitamin D by your midwife⁶. Your midwife will give you a blood test to check your vitamin D levels at your booking appointment.

Your GP or midwife will tell you more about what vitamins you’ll need throughout your pregnancy, and how to make sure you’re getting enough of them.

It’s a popular myth that pregnant women need to ‘eat for two’, but really you don’t need to eat any more than normal for now. Just make sure you’re getting a nice healthy balanced diet with lots of fruit and veg^{2, 7}.

It’s also a good idea to stay active during pregnancy. That doesn’t mean you have to become an Olympian overnight – just a brisk, 10-minute walk a day is a great start².

Finding out that you’re pregnant is a huge moment – whether you planned it or not – and can come with a whirlwind of emotions. Excitement, yet, but it’s also normal to feel anxious or overwhelmed⁸.

Remember to keep checking in with yourself and your mood, and talking to the people around you about how you feel. If you’re feeling anxious or low, talk to your GP or midwife about what extra support might be available.

You can take most at-home pregnancy tests from the first day of your missed period. If you’re not sure when your next period is due, wait until at least 21 days after you last had unprotected sex⁹. 

In the first 1-2 weeks of pregnancy, you might get some light spotting called ‘implantation bleeding’ when your fertilised egg implants itself into the wall of your uterus¹⁰.

If you think you could be pregnant and are experiencing heavier bleeding, get in touch with your GP or midwife straight away¹⁰.

Nausea during pregnancy (commonly called ‘morning sickness’ even though it can happen any time of day) usually begins early in pregnancy – between 4 weeks pregnant and 7 weeks pregnant¹¹. Most people who get morning sickness find it settles by around week 16-20, but for some people it might last longer.

At 4 weeks pregnant, your baby is still an embryo growing in your uterus or womb².

By week 12 of pregnancy, your baby (or foetus) will look fully formed and will be getting nutrients from the placenta. From then on, they’ll keep growing and developing everything they need for life outside the womb¹².

Find out what to expect week by week with our pregnancy calendar.