Pregnancy is dated from the first day of the last menstrual period. This is an old convention still in place originally based on the thought that conception occurred during menstruation.

Conception On its arrival, it becomes known as a blastocyst and floats freely within the womb cavity for about three days before embedding in the wall lining and linking to the blood supply.

Spinal Cord Your baby’s spinal cord and the brain are now almost complete and the head is beginning to look more human-like. Measuring about 1.3cm long, its limb buds have grown into tiny arms and legs with small ridges that will develop into fingers and toes.

Foetus Your baby, now called a foetus, has obvious elbows, wrists, ankles and clearly visible fingers and toes. It measures between 3-4.5cm in length and its external sex organs have begun to form.

Genitals Your baby’s genital swelling becomes a penis or clitoris. Its neck elongates and the head raises up, looking more human-like. The womb environment, like a bag of water, cushions the baby from bumps, keeps it at a constant warm temperature and allows freedom of movement.

Transparent Skin Your baby may now measure 15cm and weigh up to 125 grams. Its legs are now longer than its arms. Because it has no layer of fat under its skin it will look fragile and thin and through its transparent skin layers you would be able to see the intricate network of blood […]

Thumb Sucking Your baby can suck its thumb and now has a wide range of movements and co-ordination. Weighing about 280 grams, its dental development continues as the buds for permanent teeth are already forming behind its milk teeth.

Life Cycle The cycle of life begins early. A girl baby will already have about seven million eggs in her ovaries and nipples will already have formed on both sexes.

Heartbeat The baby’s bone centres are beginning to harden and thousands of tiny veins are now clearly visible through the baby’s skin.

Brain The last trimester is a crucial time for brain development. As the brain mass increases, the tissue folds into its characteristic walnut-like appearance.