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4 Weeks Pregnant: Your Baby’s Development

Once implanted in the side of your uterus, the fertilised egg divides into layers of cells and officially becomes an embryo. These cells will grow into your little one's body throughout your pregnancy, forming the nervous system, skeleton, muscles and organs.

Support system is under construction. The placenta, a disk-like organ that connects your body’ systems to your baby’s, begins to form and attaches to the uterine wall where the egg is implanted. The umbilical cord comes out of one side of the placenta. The amniotic fluid, which will cushion your little one throughout the pregnancy, is already forming inside an encircling membrane sac.

Measuring up. By the end of the week, the embryo measures around 0.04 inch - about the size of a poppy seed.

embryo Week 4

4 Weeks Pregnant: Your Symptoms

You might experience some spotting as the fertilised egg implants into your uterus. This is known as implantation spotting and it's completely normal.

The results are in. A home pregnancy test should show a positive result thanks to the hormone hCG released by the brand-new placenta. This same hormone is largely responsible for the nausea, or “morning sickness” that many women experience in the first trimester. Most home pregnancy tests are accurate after your first missed period, but false negatives can occur. If you have missed your period but show a negative home pregnancy test, you may want to consult your doctor.


Did you know? A miracle begins! Your baby, a little cluster of cells, burrows into the lining of your uterus and starts growing rapidly.

Quick tip for mum: From the beginning, your baby is growing and developing, so what you’re eating will impact his or her development. Every day, make sure you are taking folic acid (Vitamin B9) and prenatal vitamins (B12, C, D, E) that also contain calcium and iron. These vitamins will help your little one get off to a great start!

4 Weeks Pregnant: Your Checklist

Schedule a pregnancy confirmation appointment, if needed

Share the good news with your partner, and maybe a few close family and friends

Keep eating a healthy diet and taking your prenatal vitamins

Sign up for weekly pregnancy tips

4 Weeks Pregnant: Your Checklist

Sign up for weekly pregnancy tips

Schedule a pregnancy confirmation appointment, if needed

Share the good news with your partner, and maybe a few close family and friends

Keep eating a healthy diet and taking your prenatal vitamins

Sign up for weekly pregnancy tips:

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