This is the week your period is normally due – or late. In this case, you might begin to wonder if, or even suspect you might be pregnant.
It’s common for women to use home pregnancy tests around this time. But if you’ve already had a positive pregnancy test: congratulations!
Some women opt for a blood test to confirm their pregnancy. But rest assured, when done as per the instructions, pregnancy test kits have a very high accuracy rate, over 99%.
It’s normal to feel a combination of excitement and nervousness.
If you’re still waiting for that positive pregnancy test, try not to stress too much.
Be sure to read when to take a pregnancy test for more information.
Want to double check your estimated due date? You may want to try our due date calculator.
Remember, when the estimated due date is calculated, you need to know the first day of your last period. This day will become day 1 of pregnancy. So, around the time you miss a period, you’ve already considered to be in your fourth week of pregnancy. Find out why, here.
4 weeks of pregnancy – what to expect
By the fourth week of pregnancy, the fertilized egg has likely attached to the inside wall of your uterus.
The egg, now an embryo, is surrounded by fluid in the amniotic sac.
The placenta is still developing, but is sending out tiny hair-like tendrils.
These wrap around the abundant small blood vessels in the lining of your uterus.
Usually, the placenta will completely take over the role of sustaining your baby by 12 weeks gestation.
Under normal circumstances, your blood and your baby’s blood don’t mix.
You each have quite separate circulatory systems.
The closeness of your blood vessels to those of the placenta, however, allows the exchange of oxygen, nutrients and waste products.
4 weeks pregnant symptoms
Not all women experience early pregnancy symptoms. Ironically, many of these symptoms could be mistaken for the usual pre-menstrual symptoms you get before your period.
Things to look out for are:
- Bloating. You might experience fluid retention around the beginning of your period.
- Mood swings. Fluctuating pregnancy hormones are the cause of this and are most noticeable in the first trimester. You might experience moodiness in the week leading up to your period.
- Breast tenderness. Your breasts (sometimes nipples too) may feel sore or tender to touch.
- Cramping. Severe cramping should be investigated.
- Implantation bleeding. This can happen when the fertilized egg burrows into the uterus lining. A small amount of blood can appear.
Morning sickness during week 4
Nausea, vomiting and food aversions aren’t usually a problem just yet – it often kicks in from around 6 weeks of pregnancy. It’s around this time when the pregnancy hormone (hCG, which is short for human chorionic gonadotropin) rises. Find out more in our article about morning sickness.
Find out what other early symptoms you might experience.
Cramping at week 4 of pregnancy
If you’re experiencing cramping around week 4 of pregnancy, it can cause a great deal of anxiety. Fears of miscarriage or something going wrong can be nerve racking! However, it’s usually nothing serious.
When the fertilised egg implants, it can cause mild cramping, similar to mild menstrual cramps in your lower pelvis or back.
So around week 4 of pregnancy, any cramping, especially if not accompanied by blood, is usually the result of implantation.
If you experience any severe pain or blood loss, do see your healthcare provider.
Folate in early pregnancy
During this stage of early pregnancy, your baby’s nervous system is beginning to develop.
A layer of cells folds to form the neural tube. This becomes the baby’s brain and spinal cord.
You might have heard it’s important to get enough folate during pregnancy.
Folate helps your baby’s neural tube to develop properly and it helps to avoid birth defects.
More specifically, folate helps prevent the occurrence of spina bifida by up to 70%.
Above all, it’s important to make sure your dietary intake of folate is adequate.
Dietary sources of folate include:
- Dark leafy greens
Here are 9 top foods which contain folate.
Most prenatal vitamin supplements include the synthetic form of folate (folic acid). Find out more about what you need to know about folic acid vs folate.
The best supplement to take instead is folinic acid, especially if you’ve had problems with fertility, pregnancy complications, or miscarriage.
Effects of cigarette smoke when you’re pregnant
All women should ideally quit smoking before becoming pregnant.
If you smoke cigarettes and have become pregnant, certainly now is a good time to quit. Find out how in our article about how to quit smoking during pregnancy.
Even if you’re not a smoker, exposure to cigarette smoke has negative effects on the health of pregnant women and their unborn babies.
Second-hand cigarette smoke contains thousands of dangerous chemicals. Exposure to second-hand smoke during pregnancy increases the risk of:
- Fetal growth restriction
- Preterm birth
- Low birth weight.
You can also be exposed to toxins left in places where people frequently smoke – for example, on furnishings, paintwork, clothes, etc.
This type of exposure is third-hand smoke. Usually if a room or item smells like tobacco, it’s likely toxins are present. These toxins can make their way into your bloodstream and into your baby’s.
There’s research to show third-hand smoke can have very serious effects on your baby’s developing lungs.
Try to minimise your exposure to second-hand and third-hand smoke as much as possible.
Your baby at week 4 of pregnancy
At week 4 of pregnancy, your baby is officially classed as an embryo.
A yolk sac will nourish your developing baby, and is usually the first structure visible inside the gestational sac.
The yolk sac can usually be seen at week 5 of pregnancy, and will disappear around week 12 of pregnancy, when it will be absorbed into the gut of the embryo.
The embryo has made the journey to your uterus, and is now embedded in the rich lining of the uterine wall, dividing into two groups of cells.
One group of cells has become the embryo and the other has become the placenta.
The placenta is truly an impressive support system for your baby.
Read more in What Is A Placenta? 10 Amazing Placenta Facts.
The heart and circulatory system form rapidly. The neural tube also forms in the first 4-6 weeks of pregnancy.
The next six weeks are a critical stage of development for your growing baby.
For example, the major organs begin to develop and some organs will even begin to work!
At week 4 of pregnancy, your baby is 1mm long and about the size of a poppy seed.
Here are some articles that might be helpful if you’re 4 weeks pregnant: