Track your pregnancy week-by-week

Pregnancy week by week

4 Weeks Pregnant

Length of baby: 0.2cm (2mm)
Do start taking folic acid supplements, because folic acid has been proven to help prevent birth defects.


It is sometime this week that you will be able to find out if you are pregnant. To be most accurate, wait for a couple of days or even till a week after you miss your period before you take a home pregnancy test. If your test is positive, congratulations!

Take the time to celebrate this amazing news with your partner, but you might not want to tell everyone…..yet.

What you should do next is to start looking for a suitable OBGYN Doctor and schedule your prenatal visit. However, your first prenatal appointment should occur closer to week 8, unless yours is a high risk pregnancy or that you are suffering from some pregnancy complications such as unexplainable severe cramping or bleeding.



How big is baby at 4 weeks? Your tiny baby, now officially an embryo, is the size of a poppy seed, which is about 2mm (0.2cm).

At this stage your baby is called a blastocyst, which is basically a ball of cells.



You are still in your first trimester, so you do not need to gain much weight. By the end of the first trimester (week 12), you should be expected to gain anywhere between 0.5kg to 2kg



While many people do not experience pregnancy symptoms at week 4, your pregnancy hormones could cause some typical 4th week symptoms. However from this point on, brace yourself, because nausea and other typical pregnancy symptoms may be hitting you soon. Being 4 weeks pregnant, here are some signs and symptom that your body might be experiencing:

  • Mood Swings. Your pregnancy hormones are starting to rev up, coupled with the stress of being a new mum, your mood may be erratic. Pregnancy mood swings are the worst during the first 12 weeks, which will get better there after. 
  • Fatigue. You may feel extremely tired as your body is working hard to grow that teenie weenie ball of cells into an embryo.  
  • Bloating. Thanks to the pregnancy hormone progesterone, you will feel swollen so it is good to start to wear loose clothing.
  • Cramping. Mild cramping might hit you, but it is actually a sign that the baby has properly implanted itself onto the wall of your uterus. However should you experience severe cramping, you see your doctor right away to rule out any complications.
  • Sore breasts. Ouchh! Your breasts might start to sore and be tender to the touch as your body prepares for the arrival of the baby. Those pregnancy hormones are telling your breast to prepare the milk ducts to feed your baby!
  • Spotting. You might experience light bleeding as a result of the baby implanting itself onto your uterus. This is normal. However, should you experience a lot of blood like a period, see your doctor right away.


Start looking around for a suitable OBGYN this week, though you will probably only have your first prenatal appointment around week 8 of pregnancy.



For a 4 weeks pregnant belly, you certainly won’t look pregnant. This means that you are really far away from people giving up their seat to you on the bus or MRT. However, you need to start giving lots of love and care to your body and the tiny baby-to-be.

The baby is undergoing an important development, so start taking your prenatal vitamin with at least 400 micrograms of folic acid (Some women will require a higher dose, so do consult your doctor on this). This is very very important! Folic acid has been proven to help prevent birth defects, and you want to ensure the best health of your baby.

As you start to get bigger and your clothes seem to get smaller, start wearing loose clothing to feel comfortable. There are many maternity clothing brands that will give you comfort and afford you the style.



During week 4 of pregnancy, the ball of cells will split into the embryo and placenta.

The embryo consist of two layers: the epiblast and the hypoblast, from which all of the organs and body parts will develop.

The still-developing placenta is also made up of two layers. The cells are tunnelling into the lining of the uterus, and in the process creating space for the blood to flow so that the developed placenta will be able to provide nutrients and oxygen from your body to the baby.

The baby’s neural tube, brain, backbone and the building block of the spine is already formed.

The amniotic sac, which will house the baby, together with the amniotic fluid which will cushion your baby as she grows, is now present. The yolk sac, which produces the baby’s red blood cells and delivers nutrients until the developed placenta is ready to take over this role, is also now present.



Reminders for the week:

  • Find an Obstetrician and make your first prenatal appointment
  • Start taking your daily prenatal vitamin with at least 400 microgram of folic acid
  • Quit all activities that will be harmful to your baby, such as smoking and drinking
  • If you just got the news, go celebrate with your partner