This early on in your pregnancy, your newly fertilised egg is made up of a single cell called a ‘zygote’⁽¹⁾. Around 90 hours after fertilisation, the cells within the zygote will divide, and will continue to do so until they form a tiny mass known as a blastocyst. This will then travel from your fallopian tubes to your uterus, where it will implant itself into the lining of your womb to grow and develop⁽¹⁾. Once this happens, your baby will be referred to as an embryo⁽²⁾. 

It’s not uncommon to experience some spotting or light bleeding at around the same time your period would have been due, and this is known as implantation bleeding⁽³⁾.

Although the early signs of pregnancy (except for perhaps some implantation bleeding) may not have kicked in just yet, there’s plenty going on. In fact, your baby is developing faster now than it will at any other point during your pregnancy⁽⁴⁾.

At 4 weeks pregnant, your baby will be around the size of a poppy seed and protected by the amniotic sac, which is filled with cushioning fluid⁽⁵⁾. This is attached to a tiny yolk sac that will give your baby the nourishment they need for now. Later on, the outer layer of the sac will become the placenta, providing your baby with vital oxygen and nutrients as your pregnancy progresses^(5).

The symptoms of early pregnancy are often very subtle, and it may be that you’re not noticing any at all right now. Everyone is different. Whilst some women experience the early signs of pregnancy, others won’t experience any symptoms at all. There's really no way to tell what your experience will be. 

One of the first and most reliable signs of early pregnancy is a missed period, especially if your menstrual cycle is fairly regular. It’s possible that you’ll also experience some spotting or lighter bleeding at around the time your period would have been due, which is the result of the embryo embedding itself into your uterus⁽⁶⁾. At this point, you may be wondering if you’re pregnant and decide to take a pregnancy test.

The hormonal changes you’re going though may also result in mood swings⁽⁷⁾ - another common early pregnancy symptom. Be sure to keep an eye on how you’re feeling throughout your pregnancy, as well as after the birth of your baby. Make sure you’re taking care of yourself, and reasting when you need to. If you have any worries at all about your mental and emotional health, always speak to your doctor or midwife. You can learn more about this here.

Some other common symptoms of early pregnancy include (ref): 

• Tiredness and fatigue. This is thought to be due to the hormonal changes in your body, and it’s not uncommon to feel tired or even exhausted, especially in the first trimester⁽⁸⁾. 
• Sore and swollen breasts. One of the early signs of pregnancy, and one that can sometimes be mistaken as being connected with your menstrual cycle. This is because it can often occur just before your period is due to start⁽⁶⁾. 
• A need to wee more frequently. This is a pregnancy symptom that, in early pregnancy, is thought to be due to the increased levels of the pregnancy hormone human chorionic gonadotrophin (hCG)^(9). In later pregnancy, this symptom is usually a result of your growing baby pressing on your bladder. If you also notice a burning sensation when you wee, chills, cloudy wee or blood in your wee, please speak to your doctor as this may indicate a urinary tract infection, sometimes referred to as a UTI⁽¹⁰⁾.
• Changing tastes in food. During your pregnancy, you may find yourself craving foods that you wouldn’t normally eat, and developing a dislike of the ones you do. Whilst it’s been suggested that this might be due to hormonal changes, further research is needed here⁽⁸⁾.
• A metallic taste in your mouth. Following on from the above, some women describe experiencing a metallic taste in their mouth in early pregnancy. 
• Morning sickness. Perhaps the most well-known pregnancy symptom, morning sickness, usually starts around week 4 and is thought to be caused by pregnancy hormones. 
• A milky white discharge from your vagina. It’s perfectly normal to experience an increased level of vaginal discharge during early pregnancy, as this helps to protect your womb from infections. A milky white discharge is healthy, but always speak to your doctor if it becomes itchy and painful, changes colour or smells unpleasant⁽⁹⁾.
• Headaches and dizziness. Headaches are a common symptom of early pregnancy and usually improve with time. Try to get plenty or rest to help ease any discomfort. However, headaches can also be a sign of preeclampsia, so if your symptoms get more severe, always seek medical advice⁽¹²⁾. 
• Cramping. This can sometimes be mistaken for period pain in early pregnancy and is usually nothing to worry about. Cramping can be caused by constipation, bloating and trapped wind, as well as the ligaments in your tummy adapting and changing to support your growing baby⁽¹³⁾. 
• Acne or changes to your skin. This might include something called chloasma or ‘the mask of pregnancy’, which causes darkened patches of skin on your face.
• Bloating. A common early sign of pregnancy, the pregnancy hormone progesterone is relaxing the muscles in your womb, ready to accommodate your growing baby. As a result, you may feel bloated, and experience excess wind⁽¹⁴⁾.
• Congestion. This is most likely caused by the hormonal changes your body is going through⁽¹⁵⁾. 

Whilst the above are all common early pregnancy symptoms, if you’re worried about anything you’re experiencing, don’t hesitate to have a chat with your doctor or midwife so that they can help to put your mind at ease.

At this point in your pregnancy, it’s unlikely that you’ll look pregnant or have a noticeable baby bump. Most first-time mums don’t start showing until at least week 12, towards the end of the first trimester⁽⁵⁾. However, if you’ve been pregnant before, you may start showing a little sooner, as the muscles in your uterus have been stretched by a previous pregnancy.

By week 4, your body is starting to grow the placenta, a brand-new organ that will supply your baby with the oxygen and nutrients needed to grow and develop. The placenta will also ensure that antibodies are passed to your baby, helping them to build a level of resistance to infection in the final stages of pregnancy⁽¹⁶⁾.

Another function of the placenta is hormone production⁽¹⁷⁾. The hormones produced by the placenta support your baby to grow and develop in the womb, helping to maintain a healthy pregnancy. They also support the physical changes that are happening to your body. Progesterone and relaxin, for example, both have a relaxant effect on your muscles, allowing your uterus to adapt and make room for your growing baby⁽¹⁸⁾.

It’s unlikely that you’ll feel pregnant before you miss a period, especially if your menstrual cycle is regular and reliable. In all likelihood, you’re more likely to start experiencing some of the early signs of pregnancy when the ‘pregnancy hormone’ human chorionic gonadotrophin (hCG) starts to become active⁽⁵⁾.

Most pregnancy tests will provide a reliable result from the first day of your missed period. However, if your menstrual cycle is irregular, then the NHS advises that you take a pregnancy test 21 days after having unprotected sex⁽¹⁹⁾. You may want to try a home pregnancy test that you can use before you’ve even missed a period. 

When it comes to which pregnancy test to use, there are plenty of choices available. As long as you use them correctly and follow the instructions, home pregnancy tests are accurate and reliable.

Once a pregnancy test has confirmed that you’re pregnant, you should make an appointment to see your doctor or midwife. That way you can ensure that you’re getting the antenatal care you need for a healthy pregnancy as soon as possible⁽²⁰⁾. 

The first appointment with your midwife is known as a ‘booking appointment’ and will usually happen before you reach week 10 of your pregnancy⁽²¹⁾. During the appointment, your midwife will ask you some questions, which will help them learn more about you and your circumstances. They’ll also⁽²¹⁾:

• Take blood tests so that they can check your health and find out your blood group, as well as to test for certain conditions such as HIV or hepatitis B
• Take height and weight measurements
• Check your urine for any sign of preeclampsia and check your blood pressure

Your midwife may also discuss things like a healthy pregnancy diet, exercise during your pregnancy, and the type of birth you’re planning to have.  Remember that this is also an opportunity for you to ask any questions that you might have. 

Reviewed by Bahee van de Bor

You won’t need to follow a special or particular diet during your pregnancy unless you’ve been advised to do so by your doctor or midwife⁽²²⁾. The important thing is to ensure that you’re eating a variety of different foods every day, as that’s the best way to ensure that you and your baby are getting all of the vitamins and minerals you need. 

From the moment you find out that you’re pregnant, or if you’re trying for a baby, there are certain foods that you’ll need to either avoid entirely or reduce the amount you eat. This includes things like:

• Raw and uncooked meat
• Unpasteurised milk and certain cheeses
• Foods that contain a high level of vitamin A⁽²³⁾. 

Read more about the foods you’ll need to avoid in pregnancy here.

It’s also important to ensure that you’re taking a folic acid supplement every day - the recommended intake is 400mcg. Folic acid supports the development of your baby’s nervous system and can help to protect against spina bifida⁽²⁴⁾. We cover the importance of folic acid in more detail in week 5.

Vitamin C also helps the body to absorb iron⁽²⁸⁾. This is very important during pregnancy, as iron helps to support the development of your baby’s cognitive function⁽²⁹⁾, as well as ensuring that they get the necessary nutrients and oxygen from the bloodstream⁽³⁰⁾. 

It’s not uncommon for pregnant women to experience an iron deficiency, which is why it’s important to get plenty of it from your diet. Iron can be found in a number of foods, including⁽³⁰⁾:

• Red meat.
• Beans and pulses.
• Green leafy vegetables

If you’re concerned about your iron levels, speak with your doctor or midwife who can provide you with further advice.  

As a rule of thumb, pregnant women gain anywhere between 10 and 12.5kg during their pregnancy⁽³¹⁾. Most of this weight gain will happen after week 20 as your baby gets bigger and your body prepares for breastfeeding. 

It’s not advisable for you to go on a diet or restrict your food intake during pregnancy. Rest assured that as long as your doctor and midwife are happy with your weight and how your pregnancy is progressing, all you need to do is make sure that you’re eating a healthy and balanced diet full of a variety of foods.