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4.1: Planning

Difficulty Level: At Grade Created by: CK-12
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Key Ideas

  • Pregnancy is a natural condition, not an illness, that is the result of intercourse leading to fertilization and implantation. Conception can occur only around the time of ovulation, but knowing when ovulation occurs is very difficult.
  • The embryo grows from a tiny dot, the size of a period at the end of a sentence at implantation, to a 7.5 lb. (on average), fully functioning human infant in about 296 days. A baby is considered premature if it's born before eight months or if it weighs less than 5.8 pounds.
  • The placenta grows from fetal and maternal tissue. The size of a plate, the placenta links the baby to the mother, bringing food and oxygen in and taking away waste materials. The baby receives whatever is in the mother's blood-both good and bad.
  • The baby plays no active role in childbirth, but is pushed out by contractions of the uterus, which, at term, is a woman's largest muscle.


Pregnancy and childbirth are the topic of this section. Students learn about how and when conception takes place, then they demonstrate their knowledge by completing Activity 3-1: The Journey of the Sperm and the Egg that traces the journey of the sperm and the egg.-Next they examine pregnancy, studying the changes the mother and the fetus go through in each of the three trimesters. The importance of prenatal care is stressed. Childbirth itself is described. The section concludes with Activity 3-2: Boy or Girl? in which students see that the sex of a child is determined at the time of conception by whether or not the father's sperm contributes an X or a Y chromosome.



\begin{align*}\checkmark\end{align*} trace the journey of the sperm and the egg as they travel through the reproductive system.

\begin{align*}\checkmark\end{align*} demonstrate the role of the male chromosome in determining the sex of the baby.

\begin{align*}\checkmark\end{align*} examine fetal development.

\begin{align*}\checkmark\end{align*} discuss the importance of prenatal care.


amniotic fluid, contractions, embryo, endometrium, fetus, fertilization, labor, maternal mortality rate, menstrual period, placenta, premature, prenatal care, trimester, umbilical cord, viability

Student Materials

Activity 3-1: The Journey of the Sperm and the Egg

  • Activity Report

Activity 3-2: Boy or Girl?

  • Activity Report
  • Coin (per pair) to toss

Teacher Materials

Activity 3-1: The Journey of the Sperm and the Egg

  • Activity Report Answer Key

Activity 3-2: Boy or Girl?

  • Extra coins
  • Copy of Activity Report to use as a class tally sheet

Advance Preparation

See Activities 3-1 and 3-2 in the Student Edition.

Activity 3-1: The Journey of the Sperm and the Egg

  • None required

Activity 3-2: Boy or Girl?

  • If you wish, familiarize yourself with the story of England's Henry VIII and his quest for a male heir. Other examples would be appropriate, also. The intent is to pique student curiosity.

Interdisciplinary Connections

Math Calculations are involved in the Mini Activity. Activity 3-2 requires work with percentages and probability.

Language Arts Activity 3-1 asks the students to edit and rewrite an essay.

Background Information

An excellent source on pregnancy, fetal development, and childbirth is A Child Is Born by Lennant Nillson (Delacorte Press, 1990). It has a clear and concise text and excellent color illustrations.

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