You and Your Baby at Week 3 of Your Pregnancy

(10 minute read)

Article at a glance

  • How big is you baby at 3 weeks?
  • What are the early signs of implantation?
  • Your body at week 3: changes and developments
  • Common symptoms at week 3
  • Top tips for week 3 of your pregnancy

Pregnancy is miraculous, and week 3 marks a significant early milestone. This is because week 3 is crucial for your baby's development and your early pregnancy experience. Understanding what happens during this week can help you prepare for the many changes that are to come.

At week 3, you are technically pregnant as your egg has been fertilised, and the implantation process occurs. This is where the fertilised egg moves through the fallopian tubes into your uterus, where it attaches to the lining of the uterus and eventually grows into your baby.

How big is your baby at 3 weeks?

At Week 3, your baby is still at the very initial stage of development. Technically, the baby is not yet an embryo but a rapidly dividing cluster of cells known as a blastocyst. Your baby at this stage is incredibly small, approximately the size of a pinhead, measuring about 0.1 to 0.2 mm. Despite this minuscule size, this is a crucial stage for the baby as it travels from the fallopian tube to the uterus and begins the implantation process.

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What are the early signs of implantation?

Implantation is a significant event of Week 3. You may experience bloating, light spotting (bleeding), changes to your breasts and mild cramping. It can easily be mistaken for your period! As discussed previously, the fertilised egg (the blastocyst) arrives in the uterus and attaches itself to the uterine lining. This process is vital for the continued growth and development of the baby and triggers hormonal changes in the mother's body that support pregnancy. This is the start of your pregnancy journey. In 40-ish weeks you will be meeting your brand new baby - how amazing is that!

Your body at week 3: changes and developments

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While the baby is too small to cause physical changes in the body, hormonal changes start to occur. The body begins to produce human chorionic gonadotropin (hCG), the hormone detected by pregnancy tests. Additionally, oestrogen and progesterone levels increase to support the pregnancy.

Common symptoms at week 3

Every body, every baby and every pregnancy is different. You may experience all or some of the below common symptoms during early pregnancy. If you're ever worried about symptoms or changes to your body then do consult your GP.

Implantation Bleeding: You might experience light spotting known as implantation bleeding. It's usually lighter and shorter than a regular period, perfectly normal, and nothing to worry about. Some women don't experience any bleeding so please don't worry if you don't notice any spotting at week 3. Some women also worry that bleeding is a sign of miscarriage which is completely understandable. If you are at all worried about miscarriage, then please speak to your GP, and if helpful, share your fears with those closest to you.

Breast Changes: Hormonal fluctuations can make breasts tender or slightly swollen. Breasts can also go up in size, and this can happen rapidly! Changes in breast size and condition is normal as your hormones increase to support your changing body. If you are at all worried about changes to your breasts then please speak to your GP for an assessment.

Mild Cramping: Mild uterine cramping can occur, often mistaken for the onset of a menstrual period. Week 3 can be a confusing time as it's unlikely you would have a positive pregnancy test this early on in your pregnancy. Cramping and light spotting can easily be mistaken for a period when in actual fact it's your baby finding it's place within your womb!

Fatigue: Increased progesterone levels can lead to tiredness. Tiredness in the 1st trimester is common, and this is due to the fact that your placenta hasn't developed enough to take over supporting your pregnancy. Tiredness should subside once your placenta has taken over (around the 12-week mark). Many women find new levels of energy in the 2nd trimester - until then, rest as much as you need!

Heightened Sense of Smell: Some women report a heightened sense of smell, which can lead to food aversions or nausea. You may also experience food aversions and nausea without any heightened sense of smell. It can be surprising how you are suddenly turned off particular foods or suddenly have an urge to consume foods you've not been interested in before.

Bloating: Hormonal changes can cause bloating similar to premenstrual symptoms, which makes this time very confusing. Bloating can make you feel slightly uncomfortable but is a normal part of the early pregnancy process.

Emotional changes

Finding out you are pregnant or waiting for a positive test can bring on a whole host of emotions. This is exasperated by the surge in hormones, which will be new to your body and can be the cause of fluctuations in mood. Our advice during this period is to take it easy. If you're waiting for a positive pregnancy test and you don't get the result you're hoping for then try not to blame yourself. Getting pregnant is surprisingly hard for lots of women; for most, it takes 6-12 months. If it takes longer than 12 months, then be sure to check in with your GP. If you have just had a positive pregnancy test and you're experiencing changes to your body that you didn't expect then this can really throw you. Be sure to rest and if you can, enjoy the changes as your body prepares to do something utterly incredible - growing a brand new human!


Top tips for week 3 of your pregnancy

Take a Pregnancy Test: Perhaps you've been trying for a baby or perhaps you are suspicious of changes in your body. Whatever the reason, week 3 is a good time to take a pregnancy test. Remember, you can have a false negative test but not a false positive test. This means that if you get a negative result, then it could be that it's too early to pick up the pregnancy, so just try again in a few days. Our top tip here is to not spend lots of money on pregnancy tests - they are all the same, and a cheap home test will be the same as a fancy digital test.

Start Prenatal Vitamins: If you haven't already, start taking prenatal vitamins, particularly folic acid. Folic acid is crucial for your baby's neural tube development and helps prevent birth defects such as spina bifida. It's recommended that you start taking folic acid before you start trying for a baby so that the prenatal vitamin is within your system from the very start of conception. Please don't worry if you've just found out you're pregnant and haven't been taking folic acid; just start as soon as possible and take it daily. You can get folic acid from any high street pharmacist.

Healthy Lifestyle Choices: Continue or start a healthy diet. Obviously, if you smoke, now would be a good time to quit. Alcohol and too much caffeine are also big no-nos throughout pregnancy as these cross the placenta and can impact your baby's development. If you drink lots of caffeine, then now would be a good time to work out how you will reduce your intake to minimise the side effects of having less caffeine on top of pregnancy symptoms.

Stay Hydrated: Drink plenty of water to stay hydrated! Continue this throughout your pregnancy, try and drink to thirst rather than having lots and lots of water. Staying hydrated will also be beneficial when postnatal - especially if you plan on breastfeeding.

Rest and Relaxation: Ensure you get enough rest as your body begins to support a new life. The early stages of pregnancy can be absolutely exhausting so do take it easy as you get through the first 12-ish weeks which is when your placenta takes over and you will probably experience renewed energy.

Consult a Healthcare Provider: Schedule your first prenatal appointment. You need to tell your GP that you are pregnant who will then refer you to your local midwifery team to schedule your booking appointment and first scan.

Week 3 of pregnancy is a time of significant yet invisible changes. Understanding these early stages of pregnancy can help you prepare for the journey ahead. Remember, every pregnancy is unique, so experiences can vary widely. Always consult with a healthcare provider for personalised advice and support.



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