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Week-by-week guide to pregnancy

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!

First 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. Happy reading!

Week 4 - your first trimester

Congratulations, you're pregnant! Whether that bundle of cells inside you was planned or unexpected, we hope you have a very happy and healthy pregnancy.

What's happening in my body?

You probably don't look pregnant at all. Most first-time mums don't start showing until at least week 12. However, if this isn't your first baby, then 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. For around the first 15 days your body will be going through its normal routine – thickening the womb and releasing an egg or two. You're not technically pregnant then. But around week 2 or 3, if an egg meets sperm and fertilisation occurs, then it's showtime!

The fertilised egg then travels down a fallopian tube, dividing and redividing, until it reaches the womb. It will then bury itself into the wall (implantation) where your little bundle will make itself very comfy for the next nine months. At four weeks, your egg is now an embryo – and you are pregnant!

Am I pregnant?

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

Early pregnancy symptoms (at 4 weeks)

To start with, you might have no symptoms at all – but then the pregnancy hormone, human chorionic gonadotrophin starts to kick in.

During your first trimester (which is up until week 12, you might experience early pregnancy symptoms, such as…

  • 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 it can strike at any time)
  • tiredness
  • new likes and dislikes – anyone for blueberry muffins with pickle? You can read our advice in week 5
  • a heightened sense of smell
  • needing to wee 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 and the feeling of being bloated

If you think you could be pregnant but haven't noticed any symptoms, you still might be. You could just be lucky. Some women sail through their pregnancy feeling on top of the world. 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

This would be a good week to do the following...

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. This is a highlight for many women.

In total, most first-time mums will have around 10 appointments and two scans. Ask if it's possible to see the same carer for your entire pregnancy, to give you continuity.

Ask your midwife or doctor about antenatal classes in your area, as they get booked up very quickly. You could also contact your local branch of the National Childbirth Trust. They may offer classes such as yoga for pregnancy and birth workshops.

It’s early days, but ask your partner if they would like to go with you when the time comes (usually after week 28). This is the start of a new phase of your lives. These classes will give you the chance to meet other people – and prepare you for parenthood.

Do your best to stop smoking, give up alcohol and go easy on the cappuccinos. We know – easy to say but hard to do. Ask your midwife or GP for support.

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.

During the winter months, you should also consider taking a daily dose of 10mcg of vitamin D, as it’s hard to get this sunshine vitamin when the skies are grey. It’s worth checking 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.

Get moving! It’s recommended that pregnant women do 150 minutes of exercise throughout the week. You could start off with just 10 minutes of daily exercise. Perhaps take a brisk walk in the park or go for a swim. If you start any classes, make sure the instructor knows you’re pregnant. Listen to your body and do what feels right for you.

Don’t eat for two! That’s a big myth. 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 bottle it up – you’re important, so ask for help if you need it.

This week's treat

Find yourself a favourite non-alcoholic tipple. Here are some easy mocktail recipes by Drinkaware. Enjoy!

Go to week 5

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