Pregnancy Body Changes at 4 Weeks Pregnant

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Congratulations! Now that you're 4 weeks pregnant, your focus from now on is to be healthy. Rest, eat right, get regular exercise, and establish a steady schedule of prenatal visits with your care provider. You're doing everything for two now, which means taking care of two people the very best that you can.

At 4 weeks pregnant, you may be experiencing any of the following pregnancy symptoms: missed period, nausea, vomiting, dizziness, headaches, bloating, a feeling of fullness, light cramping, poor appetite, frequent urination, and breast tenderness. If you've had some minor spotting in the past week, it may be implantation bleeding, which is not a cause for concern.

Some women have no symptoms at all at 4 weeks, which is perfectly normal. As soon as you discover you are pregnant, schedule your first appointment with your OB/GYN or midwife. Early prenatal care is important.

After 4 weeks of pregnancy, a test will probably be able to detect your pregnancy. Pregnancy tests look for a special hormone in the urine or blood that is only there when a woman is pregnant. This hormone, hCG, is the hormone that is measured in pregnancy tests. The hCG levels increase drastically each day you are pregnant.

Your Baby's Growth and Development at Week 4

The baby's brain, spinal cord, heart, and other organs begin to form. Your baby is now about 1/25 of an inch long (0.04 inches).

Four weeks into your pregnancy, your baby (called an embryo) consists of two layers of cells — the epiblast and the hypoblast, which will eventually develop into all of your baby's organs and body parts.

Two other structures that develop at this time are the amnion and the yolk sac. The amnion, filled with amniotic fluid, will surround and protect the growing embryo. The yolk sac will produce blood and help to nourish the embryo until the placenta takes over that role.


A 4-weeks pregnant ultrasound shows an embryo in the amniotic sac.
A 4-week ultrasound shows a tiny mass of cells starting to form. By next week, it will be an embryo.

The placenta has also started to form — it is producing hCG, among other hormones, which is an important hormone in pregnancy.

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