Pregnancy and the Birth for a First Time Mum. pregnancy | Page 11

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The development of the foetus can be described in key
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milestones. These are as follows.

4 weeks: The embryo is 4 mm long and has a heartbeat. The placenta has
begun to form although it's in the early stages. Neural tubes are developing which
will ultimately form the baby’s brain and spinal cord.
5 weeks: The embryo is about 12 mm and has the start of arms and legs. It has three distinct
layers: the outer ectoderm, which will create the nervous system, the endoderm, which will
develop into internal organs like the intestines, lungs, and bladder; and the middle mesoderm,
which eventually creates the heart and circulatory system.
8 weeks: The embryo is now about 46 mm and is a foetus. It has begun to develop a face and its
eyes are noticeable. The foetus’s brain is developing at 100,000 cells per minute.
9 weeks: It is during these first few weeks of its development that tissues forms and reproductive
organs develop.
12 weeks: The foetus is 92 mm long and has all its internal organs. Two weeks later its kidneys
start working. The muscles are developing, making the foetus stronger and more mobile.
16 weeks: First kicking movements are felt by the mother. The skeleton within the foetus begins
to harden.
20 weeks: The foetus is normally fully formed. The placenta is almost as big as the foetus at this
stage. Vernix caseosa begins to coat the skin. Over the coming weeks, the nerve endings begin to
form meaning the foetus can feel and touch.
26 weeks: The foetus has grown to about 250 mm. Basic life functions as being practised by the
foetus, such as breathing. Vitamins and minerals continue to be absorbed through the placenta
and fluid. The eyes begin to open at this stage too.
35 weeks: The foetus takes on 40g of fat a day. This is to keep him or her warm after delivery.
38 weeks: Birth usually takes place 38 weeks after conception.
(Parents.com 2016)

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