1- 4 WEEKS PREGNANCY

Your baby at 4 weeks

In weeks 4 to 5 of early pregnancy, the embryo grows and develops within the lining of your womb.

The outer cells reach out to form links with your blood supply. The inner cells form into 2, and then later into 3 layers.

Each of these layers will grow to be different parts of your baby’s body:

• the inner layer becomes the breathing and digestive systems, including the lungs, stomach, gut and bladder
• the middle layer becomes the heart, blood vessels, muscles and bones
• the outer layer becomes the brain and nervous system, the eye lenses, tooth enamel, skin and nails

In these early weeks of pregnancy, the embryo is attached to a tiny yolk sac that provides nourishment.

A few weeks later, the placenta will be fully formed and take over the transfer of nutrients to the embryo.

The embryo is surrounded by fluid inside the amniotic sac. It’s the outer layer of this sac that develops into the placenta.

Cells from the placenta grow deep into the wall of the womb, establishing a rich blood supply. This ensures the baby receives all the oxygen and nutrients it needs.