4 Weeks Pregnant ─ Pregnancy Symptoms

During Week 4 the Implanted Egg in your Uterus Starts to Develop

258 DAYS TO GO. . .


Breast Pain
52% of women experience breast pain and tenderness as a symptom during week 4 of pregnancy. More >>
51% of women experience fatigue as a symptom during week 4 of pregnancy. More >>
40% of women experience bloating as a symptom during week 4 of pregnancy. More >>

The embryo is implanted into your uterine wall, and pregnancy hormones are being produced. However, it may be difficult to detect these hormones quite yet with a pregnancy test, so although it is hard, you should wait before you do a test. Pregnancy tests detect the levels of hCG in your urine, but at this stage your levels of hCG may not be high enough to render a positive result.

Pregnancy 4 weeks pregnant egg development


The Uterus Lining produces hormones and creates a clot to prevent blood loss.

The Yolk Sac provides nourishment for the embryo.

The Embryo currently consists of a few layers of cells that will be changing rapidly to form the baby's body.

The Placenta cells will begin to penetrate the lining of the uterus.

The Amniotic Cavity will later become the amniotic sac that protects the baby.

Week 4 baby embryo size sesame seed
Embryo Size
Your baby is about the size of a sesame seed during week 4.

LENGTH: 0.05 in / 0.13 cm
WEIGHT: 0.004 oz / 0.11 g

View Weekly Growth Chart >>

This waiting game can be very stressful, and you might find yourself analyzing every feeling in your body. You may even have some light spotting, but try to remain calm, this can happen. As the blastocyst becomes completely embedded in the wall o f your uterus, some light bleeding may occur around the time that you would normally start your period. There is no cause for alarm, but it would not hurt to see your doctor for a checkup.

The blastocyst is beginning to form two sacs within itself. The smaller sac will become the amniotic sac, while the larger will become the yolk sac that feeds the early embryo. The umbilical cord will develop close to the amniotic sac that is forming at this stage. You may be noticing that you are feeling a bit irritable and tired and that your breasts are tender, these may be signs that you are pregnant. You may want to talk to a friend or relative who has gone through a pregnancy. Patience is key.

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