0 To 8 Weeks Pregnant

Your weeks of pregnancy are dated from the first day of your last period. This means that in the first 2 weeks or so, you are not pregnant. Your body prepares for ovulation as usual.

Weeks 1 to 2 - preparing for ovulation

You ovulate (release an egg) around 2 weeks after the first day of your period. This depends on the length of your menstrual cycle.

All women who can get pregnant are advised to take a 400 micrograms (mcg) folic acid supplement every day. Folic acid supports your baby’s spine and brain development.

Folic acid before or during pregnancy

What to expect in the first trimester

Week 3 - fertilisation

After you release an egg (ovum), it travels down the fallopian tube. This is the tube that transports the egg from the ovary to the womb (uterus).

After sex, there may be sperm in the fallopian tube. At the moment of conception, one of the sperm enters and fertilises the egg.

The fertilised egg continues to move towards the womb. It begins as a single cell that divides again and again.

By the time the fertilised egg reaches the womb, it has become a hollow ball of cells known as a blastocyst. When the blastocyst reaches the womb, it attaches to the lining of the womb and starts to develop into an embryo.

Week 4 - implantation

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

The outer cells reach out and form links with your blood supply. After some time, they will form the placenta (afterbirth).

The inner group of cells will develop into the embryo. These inner cells form 3 layers at first. Each of these layers grow to be different parts of the body.

These are:

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

In these early weeks, the embryo attaches to a tiny yolk sac. This sac provides nourishment to the embryo.

A few weeks later, the placenta is fully formed and takes over the transfer of nutrients to the embryo.

Cells from the placenta grow deep into the wall of the womb. Here, they establish a rich blood supply. This makes sure the embryo receives all the oxygen and nutrients it needs.

Week 5 of pregnancy

This is the time of the first missed period. It is when most women start to think they may be pregnant.

The embryo produces more of the pregnancy hormone (hCG). This causes your ovaries to stop releasing eggs. Your ovaries will also produce more oestrogen and progesterone. These hormones stop your period and help the placenta to grow.

The pregnancy hormone, hCG, is also present in your pee. Home pregnancy tests detect the levels of hCG in your pee.

Home pregnancy tests

Embryo developing

At this stage, the nervous system is developing in the embryo. The foundations for the major organs are also in place. The embryo is around 2mm long and is about the size of an apple seed.

The embryo's outer layer of cells form a hollow tube called the neural tube. This will become the brain and spinal cord.

At the same time, the heart is forming as a simple tube-like structure. The embryo has some of its own blood vessels and blood begins to circulate. A string of these blood vessels connects you to the embryo, and will become the umbilical cord.

If you haven't been taking folic acid, you can still start now.