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Prenatal Form and Function – The Making of an Earth Suit


Unit 17:   7 to 8 Months (28 to 32 Weeks)

  Closer Look: 
  Applying the Science: 
Play Movie - Human fetus 7 to 8 months
Movie 17.1 - 7 to 8 Months
3D Ultrasound of 7 month fetus
Figure 17.1 - 3D Ultrasound
The Biology of Prenatal Development DVD
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Each day, the adrenal glands produce large amounts of steroid products. The adrenal glands have doubled in size since week 20, and will double again before the end of pregnancy.1


Breathing movements become more common, occurring 30 – 40 percent of the time in an average fetus.2

father and baby sleeping
Sleep patterns follow circadian rhythms starting in the 28 week fetus.
Play Movie - 7 month fetus, Breathing Movements
Movie 17.2 - Breathing Movements


Starting at 32 weeks, true alveoli (al-ve’o-li), or air “pocket” cells, begin forming from alveolar ducts. Development of alveoli continues through birth and until about 8 years of age.3

Play Movie - 8 month 1 week fetus, Alveoli Formation
Movie 17.3 - Alveoli Formation
boy playing
As this boy reaches his 8th birthday, his lungs will finally have their complete number of alveoli – those important microscopic structures that help our body exchange oxygen and carbon dioxide.
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7 to 8

1 Mesiano and Jaffe, 1997. 62-63.
2 Connors et al., 1989. 932; de Vries et al., 1985. 117; Patrick et al., 1980. 26, 28; Visser et al., 1992. 178.
3 Lauria et al., 1995. 467.