Week-by-week guide to pregnancy

happy couple looking at pregnancy test results
When you're pregnant, you have lots of questions. Our week-by-week pregnancy guide is packed with lots of useful information. From what's happening inside your body, to how your baby is developing, and tips and advice on having a healthy pregnancy – this is your one-stop pregnancy guide!

1st trimester

Our week-by-week pregnancy guide is full of essential information. From early pregnancy symptoms to how your baby is growing and developing, you'll find it all here.

Week 4 – your 1st trimester

What's happening in my body?

You probably don't look pregnant yet. If it's your first pregnancy you might not start showing until at least week 12. However, if this isn't your first baby, you may start showing sooner, as the muscles in your uterus (womb) and belly may have been stretched from your last pregnancy.

Pregnancy is dated from the first day of your last period. Read about you and your pregnancy at 1 to 3 weeks on the NHS website.

Am I pregnant?

Wondering when to take a pregnancy test? Some of the home tests can tell you if you're pregnant after about 3 and a half weeks – and are 99% accurate.

Early pregnancy symptoms (at 4 weeks)

To start with, you may not have any symptoms at all. When the pregnancy hormone “human chorionic gonadotrophin” starts to kick in, you may experience early pregnancy symptoms.

During your 1st trimester, which is up until week 12, you may experience:

  • a missed period (often one of the first signs of pregnancy)
  • a metallic taste in your mouth
  • sore breasts
  • nausea - also known as morning sickness, although you can experience it at any time (read about morning sickness in week 6)
  • tiredness
  • new food likes and dislikes
  • a heightened sense of smell
  • needing to pee more frequently
  • a milky white pregnancy discharge from your vagina
  • light spotting as the fertilised egg burrows into your uterus (see your doctor if you get bleeding during pregnancy)
  • cramping, a bit like period pains
  • darkened skin on your face or brown patches – this is known as chloasma faciei or the “mask of pregnancy”
  • thicker and shinier hair
  • bloating (read about dealing with bloating in week 10)

If you think you could be pregnant but haven't noticed any symptoms, you still might be. Everyone's different and nobody else will have a pregnancy just like yours.

What does my baby look like?

Your baby, or embryo, is about 2mm long (about the size of a poppy seed) and growing rapidly in your womb. It's protected by an amniotic sac, which is filled with cushioning fluid, and attached to a tiny yolk sac that provides all the nourishment it needs. The outer layer will later develop into the placenta and provide your baby with oxygen and nutrients.

Action stations

Share the news with your GP or ask for an appointment with a midwife at your doctors' surgery. Alternatively you can refer yourself to your local hospital - look for contact details on their website.

You'll need to arrange a booking appointment . This usually takes place between weeks 8 and 12, and takes around an hour. You can talk about the options for your pregnancy and the birth. Plus you'll be offered screening tests for infectious diseases, and conditions such as Down's syndrome. You could ask about the Maternity Transformation Programme and how it could benefit you.

You will get your first dating scan at 8–14 weeks.

If it's your first pregnancy you will probably have around 10 appointments and 2 scans in total. Ask if it's possible to see the same carer for your entire pregnancy, to give you continuity.

Ask your midwife or doctor about online antenatal classes – they may be able to recommend one. The charity Tommy's has lots of useful information on antenatal classes and preparing you for birth.

Antenatal classes will give you the chance to meet other people and prepare you for parenthood. The NCT offers online antenatal classes with small groups of people that live locally to you.

Take prenatal vitamins. You're advised to take 400mcg of folic acid every day, until at least week 12. This helps to form your baby's nervous system and offers some protection from conditions such as spina bifida.

To keep bones and muscles healthy, we need vitamin D. From late March/early April to the end of September, most people make enough vitamin D from sunlight on their skin. However, between October and early March, consider taking a daily vitamin D supplement because we cannot make enough from sunlight. Some people should take a vitamin D supplement all year round - find out if this applies to you on the NHS website. You just need 10 micrograms (it's the same for grown-ups and kids). Check if you're entitled to free vitamins.

Do you think you or your partner could have a sexually transmitted infection (STI)? If so, get checked out, as this could affect your baby's development. Talk to your midwife or GP, or visit a sexual health clinic.

It's recommended that you do 150 minutes of exercise a week while pregnant . You could start off with just 10 minutes of daily exercise - perhaps take a brisk walk outside. Check out Sport England's #StayInWorkOut online exercises (scroll to the pregnancy section). Listen to your body and do what feels right for you.

There's no need to eat for 2. If you pile on the pounds, you could put yourself and your baby at risk of health problems such as high blood pressure. Eat healthily, with plenty of fresh fruit and veg, and avoid processed, fatty and salty foods. You may be able to get free milk, fruit and veg through the Healthy Start scheme.

If you have a long-term health condition, then let your specialist or GP know you're pregnant as soon as possible. Don't stop taking any regular medication without discussing it with your doctor first.

How are you today? If you're feeling anxious or low, then talk to your midwife or doctor. They can point you in the right direction to get all the support that you need. You could also discuss your worries with your partner, friends and family. You may be worried about your relationship, or money, or having somewhere permanent to live. Don't keep it to yourself. It's important that you ask for help if you need it.

You and your family should follow the government and NHS guidance on coronavirus (COVID-19):

  • read government guidance on how to stay safe from COVID-19
  • get NHS advice about COVID-19
  • use the NHS COVID-19 app for England and Wales – it's the fastest way of knowing when you've been exposed to COVID-19
  • To find out about about COVID-19 and pregnancy, childbirth and breastfeeding, have a look at advice on the:

  • NHS website
  • Breastfeeding Network
  • World Health Organization
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