Diapositiva 1

1
UNIT
Human reproduction
5
THE PHASES OF FOETAL DEVELOPMENT
Biology and Geology 3. Secondary Education
2
UNIT
5
The phases of foetal development
FIRST TRIMESTER
Month 1 The embryo measures 4 mm. The
development of the head begins. The heart is
formed and starts to beat.
Month 2 The extremities develop. Start of the
formation of the brain and the internal organs.
Month 3 The fingers and toes form and the nails
appear. The eyes are almost completely
developed.
Biology and Geology 3. Secondary Education
3
UNIT
5
The stages of foetal development
SECOND TRIMESTER
Month 4 The foetus measures 15 cm. It starts
to make movements. The skin is almost
transparent.
Month 5 The foetus becomes more active and
moves more. Hair starts to appear on the head,
the eyebrows and the eyelashes.
Month 6 The skeleton partially ossifies. The
foetus shows some reflexes, such as frowning or
sucking its fingers.
Biology and Geology 3. Secondary Education
4
UNIT
5
The stages of foetal development
THIRD TRIMESTER
Month 7 The foetus is 40 cm long.
Month 8 The skin thickens and turns a pink
colour. The foetus moves into the head-down
position.
Month 9 The foetus measures between 45 and 50
cm and weighs between 2.5 and 3 kilos. The
lungs are fully mature.
Biology and Geology 3. Secondary Education