Pregnancy calendar

weeks pregnant

4 weeks pregnant - what to expect

Congratulations on your exciting news! Tommy’s midwives are here to guide you through every stage of your pregnancy and help you get to know your growing baby.

4 weeks infographic.

Each week we’ll offer advice on how to cope with pregnancy symptoms (the good, the bad and the ugly), and take you through the practical bits, like booking appointments.

Before week 4

If your periods are usually regular, conception is likely to happen in the middle of weeks one to four. You are very unlikely to know you're pregnant at this stage.

Pregnancies are measured from the first day of your last period rather than the day you actually conceived your baby. This is because it's not always easy to be sure of the exact date you became pregnant.

“I spent the entire week my period was due running to the loo, just to double check I didn’t have my period. My boobs felt tender - but that can be a sign of PMT too. I took an early test in the end and couldn’t believe it when it showed positive.” Ayida, mum of one

Although a fertilised egg may have implanted in your womb just two weeks ago, if the first day of your last period was four weeks ago, you are officially four weeks pregnant! This may seem odd if you think you can definitely date the pregnancy more recently.

Get weekly updates on your baby's development from our expert midwives straight to your inbox.

What does my baby look like?

The tiny person inside you is the size of a poppy seed. A little dot, measuring about 2mm.

They may be miniscule but big things are happening: The fertilised egg has snuggled into the side of your womb. It divides into layers of cells that will eventually become different parts of your baby’s body.

Your baby’s nervous system and heart are developing. Amazingly your tiny dot already has some of its own blood vessels and blood is starting to circulate. A string of these blood vessels connects you to your baby. This will eventually become the umbilical cord.

Right now, your poppy seed is known as an embryo. They get their energy and nourishment from a yolk sac (until the placenta takes over in a few weeks). Your baby is surrounded by amniotic fluid within the amniotic sac, providing a comfy cushion for them throughout your pregnancy.

Your symptoms - what to expect

Noticed some light spotting?

You might notice some very light bleeding, or ‘spotting’, known as implantation bleeding. This can be caused by your little seed burrowing into the lining of your womb. It often happens around the time your period would have been due and is relatively common.

You may also have some period-like cramping in these early weeks.

If you notice any bleeding at any stage of your pregnancy, though, it's important to get it checked out by your doctor or midwife.

Sore boobs

This week, a surge in progesterone can start to make your boobs feel tender, heavy and sore - a bit like how they might feel before your period.

Remarkably, these are pregnancy hormones already preparing your body to produce milk. This tenderness usually eases off by the end of the first trimester.

Find out how to deal with first trimester pregnancy complaints here.

Actions to take

Say bye bye booze

It’s time to quit cigarettes and wave wine ’o’ clock goodbye for a few months.

Here’s our guide to alcohol and pregnancy.

Find out more about the effects of smoking in pregnancy.

And if you’re still struggling to stop smoking, these ten steps towards quitting could help.

If you use street or recreational drugs, stop or ask your doctor for advice on stopping safely.


Sexually transmitted infections (STIs) such as chlamydia, gonorrhoea, syphilis and genital herpes can affect your baby's health during pregnancy or birth.

If you think you or your partner might have an STI, go for a check-up as soon as you can. Your doctor or midwife can tell you where you can find your nearest sexual health clinic.

Don't worry, nobody will judge you and it's important to be checked as soon as possible.

Start taking your supplements

There are two vitamins that are very important in pregnancy and that you can take as supplements: Folic acid and vitamin D.

Folic acid (folate) is naturally present in leafy vegetables, fruits and berries, beans and wholegrain products - but keep taking folic acid supplements too, until at least week 12.

Folic acid helps in the formation of your baby's nervous system and reduces the risk of spina bifida, which is where the baby's spine doesn't close up properly.

You should take:

  • 10 micrograms of vitamin D each day throughout your pregnancy and if you breastfeed
  • 400 micrograms of folic acid each day – you should take this from before you are pregnant until you are 12 weeks pregnant

Find out more about important supplements in pregnancy here.

Book a GP appointment to let them know your news

Once you know you’re pregnant, make an appointment to see your doctor or a midwife to get any advice you need and to be booked in for your pregnancy care appointments.

This is an important time to talk about any health issues you have to make sure your pregnancy goes well. Tell your doctor about any medication you may be on, especially long-term medicines for conditions related to diabetes, hormone therapy, heart problems and so on.

Find out what questions you'll be asked at the booking appointment here.

If you have an existing mental health problem

If you have a pre-existing mental health condition and take medication, tell your doctor and the person who prescribed the medication that you’re pregnant as soon as possible.

They will talk to you about whether your medication is safe in pregnancy or whether you should consider a different treatment.

Find out more about your mental wellbeing in pregnancy here.

What are my chances of miscarrying?

It’s a sad thing to think about, but up to one in five pregnancies will end in miscarriage in the first three months.

If you do experience light bleeding, spotting or stomach pains, this doesn't mean you are going to miscarry. However, you should always speak to your doctor or midwife and ask for advice.

Find out when you should contact your midwife immediately here.


1. You and your baby at 0–8 weeks pregnant, NHS Choices:  [accessed 7 May 2015] (last reviewed: 9 February 2015; next review due: 9 February 2017)

2. You and your baby at 0–8 weeks pregnant, NHS Choices: [accessed 28 February 2015] (last reviewed: 9 February 2015; next review due: 9 February 2017)

3. You and your baby at 0–8 weeks pregnant, NHS Choices: [accessed 28 February 2015] (last reviewed: 9 February 2015; next review due: 9 February 2017)


5. Signs and symptoms of pregnancy

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Last reviewed on April 1st, 2015. Next review date April 1st, 2018.

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  • By Anonymous (not verified) on 15 Jan 2017 - 17:13

    how do I know how long I av been pregnant without going for scan cos i missed my period since two months ago

  • By Midwife @Tommys on 16 Jan 2017 - 09:28

    Hi there. You can work it out by pinpointing the first day of your last menstrual period. For ease, you can use a pregnancy calculator like the one i have posted for you below.

  • By Anonymous (not verified) on 10 Jan 2017 - 13:25

    my due period was on 4 January 2017 then Its late by 2 days. its came on 6 this month could I be pregnant

  • By Midwife @Tommys on 10 Jan 2017 - 13:37

    It is not unusual for period dates to vary by a few days and for your cycle to be a little irregular. If you have had your period this month, a pregnancy is extremely unlikely. Best wishes

  • By Anonymous (not verified) on 27 Dec 2016 - 09:22

    On the 27th of November my boyfriend came in me after that I started bleeding and I was bleeding heavily with clots for about 2 weeks. We recently had sex again this weekend and he came in me both days. I'm now experiencing clear discharge with a little blood but i started bleeding a little more.
    What's going on ? Am I pregnant or ?

  • By Midwife @Tommys on 6 Jan 2017 - 09:19

    Hi, Sorry to hear you are experiencing such confusing and difficult symptoms. I would advise for you to do a pregnancy test if you have not done so already. If this is positive and you are bleeding then I would advise to make contact with your GP for a review. If the pregnancy test is negative and the bleeding has stopped and you feel well then rest up and just monitor how you are feeling. If the bleeding continues or you feel unwell or have other symptoms then again see your GP if you are sure it is not your period.

  • By Midwife @Tommys on 30 Nov 2016 - 10:07

    If your period is late you can do a pregnancy test. The brown discharge you mention may be implantation bleeding. The breast tenderness, cramps and backache may be a pre menstrual symptoms or early pregnancy but you wont know until you take a pregnancy test. Please feel free to call us here at Tommy's 0800 0147 800 anytime weekdays 9-5 pm.
    Tommy's Midwives

  • By Anonymous (not verified) on 30 Nov 2016 - 09:35

    few week I've been discharging brownish my breast sore, stomach cramp for a week n backpain now I've missed my period in 2days n now am discharging white creamy

    help me pls

  • By Anonymous (not verified) on 29 Nov 2016 - 06:06

    4 weeks i havent my meanstration and i feel something different in my stomoch, did im pregnant?

  • By Midwife @Tommys on 29 Nov 2016 - 09:40

    If you have missed the first day of your menstrual period then you can take a pregnancy test. If you get a positive test result on the first day of your missed period, it's probably about two weeks since you conceived. Please feel free to contact one of our Midwives for a chat on our helpline 0800 0147 800 if you want more advice. A Midwife is always here from 9am till 5pm, Monday to Friday

  • By Anonymous (not verified) on 19 Oct 2016 - 01:43

    I am four pregnant when start feel movement

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