Elisabet O. Orville
“The most hazardous time in an infant’s life is the perinatal period, the days immediately before and 28 days after birth. For those babies who survive, over seven decades of life may be anticipated.”
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My unit concerns this critical perinatal time when the fetus, who is adapted to life inside its mother, must suddenly at birth be able to survive in a totally different environment. For nine months, the fetus has all its needs taken care of by the mother through the placenta: food and oxygen diffuse in and wastes move out, it is protected from many germs, kept warm and supplied with its own gymnastics studio in the amniotic fluid of the womb.
At the same time, all its organ systems are preparing for life outside the womb however, because it must be ready at birth to make an immediate switch-over to its new environment.
Consider all the things that have to take place when the umbilical cord is cut:
The neonate breathes air for the first time, forcing fluid out of its lungs.
It must close two shunts in its circulatory system so that blood will go to the lungs (instead of the placenta).
The immature liver starts excreting waste products, but not very efficiently,with the result that many newborns are jaundiced.
The neonate must keep warm in an environment that is much colder than its mother’s body.
It must start producing its own antibodies to protect it from infection in a very germy world.
Its reflexes must be well enough developed to enable it to suck and swallow.
This unit on the perinatal period would be appropriate for biology, human physiology and advanced biology classes. (Much of it could also be used in middle school science classes.) lt could be taught as a three to four week unit towards the end of the school year after students have studied the major body systems
or
parts of it could be used wherever applicable. The important thing to emphasize in either case is the contrast between fetal and adult adaptations to their two different environments.
The field of perinatology is so new that very little information has reached the level of high school textbooks yet, although there are almost daily newspaper articles such as, “Operation saves kidney of fetus” or “New test developed to find sickle cell anemia in fetuses”. The information in this unit is a summary of what I learned from medical journals and books at the Yale Medical School Library (most of the references are later than 1970), and also from Dr. Maurice J. Mahoney’s stimulating seminar, “Human Fetal Development” at the Yale Mew Haven Teachers Institute.
Many of the activities in the unit rely on materials and expertise supplied by Dr. Mahoney and his associate, Dr. Cara Smith, of the Department of Human Genetics at Yale. I am grateful for their generosity and enthusiasm.
Ultrasound photo of Third trimester fetus.
Courtesy: B. Cherry
(figure available in print form)
