3 weeks pregnant: Baby’s development, symptoms, and tips

In this week, the fertilised egg will burrow into the lining of the uterus (womb) in a process called implantation. This usually occurs about 5 – 6 days after ovulation, so it may fall into the fourth week of your pregnancy depending on your cycle.

Implantation can come with some symptoms, including light bleeding and abdominal cramps. For some people this can be really noticeable, but other people will not feel anything at all as their baby gets comfy in its new home.

There is not yet a foetus at 3 weeks, as the cells that make up your growing baby are still so small and in such an early stage of development that they are not even quite an embryo yet. If you were to try a regular ultrasound scan at this point, there would be nothing much to see and no heartbeat to detect. However, there is lots going on during this point of the first trimester, as the main structures of the body and organs begin to form.

It is possible to test positive in the third week of pregnancy, as your body starts producing the hormone Human Chorionic Gonadotrophin (HCG), which stops you having a period and shows in your urine – this is what home pregnancy testing kits can detect when you miss your first period.

However, if you have arrived at this page after doing a pregnancy test that tells you you’re 3 weeks pregnant, you might be further along than you think. Those tests date from the point of conception, so you can probably add two weeks or even more.

You can check our due date calculator to work out when your baby is due.

The most likely symptoms this week will relate to ovulation and implantation. All the dramatic body changes are happening on a very small scale inside your fallopian tubes and womb. You can expect your usual symptoms of ovulation, alongside possible light bleeding and cramps. As the HCG hormone starts to be produced, you may also get some more typical pregnancy symptoms, like tiredness and nausea – but most likely this won’t start for another few weeks.

At this early stage, your pregnancy won’t disrupt your routine too much, but there are some do’s and don’ts.

It’s best to avoid smoking, drugs and alcohol at this stage – though if you had a glass or two before you found out you were pregnant, don’t panic. Do try to start those healthy habits, like eating well, getting to bed at a reasonable hour, and staying active. There are no exercises you need to avoid at 3 weeks pregnant.

Preparing for your booking-in appointment

If you’ve just found out you’re pregnant, you might be wondering when you should speak to a doctor or midwife. Booking-in appointments are usually at around 8 weeks, but you can call earlier to get the appointment in the diary and start noting down any questions you’d like to ask them.

Folic acid supplements

If you haven’t already, it’s time to start taking folic acid supplements, which help support normal development of your baby. Folic acid can also be found in foods like leafy greens, but the supplement will ensure you have plenty. There are also other supplements recommended for your first trimester and throughout your pregnancy – read our guide to vitamins and supplements for more information.

There is plenty of advice out there about which foods to avoid and how to maintain a healthy diet during pregnancy. The most important thing to remember is to try to eat a balanced diet across each week – the occasional treat is fine.

As morning sickness develops over the next couple of weeks, eating well could become more difficult – so start making healthy choices now and try to turn them into healthy habits for the duration of your pregnancy.

In terms of what not to eat, we have a guide to foods to avoid during pregnancy. Though there are some foods and drinks to avoid altogether, many of the recommendations are to limit your intake – e.g., of certain fish, caffeine, etc.

Is 3 weeks too early to detect pregnancy?

No – in fact, this is when many people find out they are expecting. After conception, the HCG hormone will start to be produced, which is what will enable a home pregnancy test to indicate a positive result.

How are you supposed to feel at 3 weeks pregnant?

There is no ‘supposed to feel’ at 3 weeks pregnant – or, you could argue, at any point during pregnancy (or life). Everybody is different.

Some people get ‘a feeling’ that they’re pregnant, which is then proved right by the presence of a positive pregnancy test. Some people feel like they’re getting their period, without actually getting their period. Some people feel nothing at all. All of those feelings are normal and valid.

Is cramping at 3 weeks normal?

Some people experience abdominal cramping during implantation, or even as a side-effect of ovulation. These are usually light cramps and may coincide with some light bleeding or spotting. This does not happen to everyone, and it should not be a cause for concern if you don’t experience cramping. If cramping is more severe, talk to a medical professional.

Is morning sickness at 3 weeks normal?

Morning sickness doesn’t usually begin until you are around 6 weeks pregnant. However, morning sickness is thought to derive in part from the rise in pregnancy hormones, which will begin to be released following fertilisation of the egg. Therefore, some people might find their morning sickness starts earlier than expected.

What should I avoid at 3 weeks pregnant?

Avoid foods like raw shellfish or unpasteurised cheese, both of which present a risk of bacterial infection that could harm your baby. As soon as you find out you’re pregnant, you should also avoid smoking, alcohol, drugs, and reduce caffeine intake in accordance with the guidelines. For more information, view our guide on foods to avoid.

Got questions? At the HiPPBabyClub, we bring you real-world advice and support from HiPP parents, midwives, nutritionists and more. Join our Baby Club to find out more.