© Goodheart-Willcox Co., Inc.

4 Pregnancy

© Goodheart-Willcox Co., Inc. Key Terms cell sperm ovum conception zygote fallopian tubes uterus genetic factors chromosomes dominant traits recessive traits multiple pregnancy fraternal chorion continued

© Goodheart-Willcox Co., Inc. Key Terms identical prenatal development germinal stage amnion placenta umbilical cord embryonic stage embryo cartilage fetal stage fetus quickening age of viability

© Goodheart-Willcox Co., Inc. Objective Describe what happens during conception.

© Goodheart-Willcox Co., Inc. Conception Cell is the smallest unit of life that is able to reproduce itself Cell Sperm is the male germ cell Sperm Ovum is the female germ cell Ovum Conception occurs when ovum and sperm combine Conception Zygote is a single cell formed at conception Zygote – also called a fertilized egg continued

© Goodheart-Willcox Co., Inc. Conception Fallopian tubes extend from the sides of the uterus Fallopian tubes – where the ovum is fertilized Uterus is the organ in which the baby develops Uterus

© Goodheart-Willcox Co., Inc. Objective Explain how genetic factors affect prenatal development.

© Goodheart-Willcox Co., Inc. Genetic Factors and the Unborn Baby Genetic factors are traits passed through the genes Genetic factors – affect all stages of growth and development Genome is a genetic blueprint that guides growth and development during pregnancy – gives cells instructions for family-like traits that will unfold throughout life continued

© Goodheart-Willcox Co., Inc. Genetic Factors and the Unborn Baby Nucleus is the center of the cell Genetic code is a set of instructions for development DNA store the genetic code Chromosomes carry the DNA Chromosomes

© Goodheart-Willcox Co., Inc. Objective Describe how a person inherits traits through genes.

© Goodheart-Willcox Co., Inc. Chromosomes and Genes Chromosomes – each person has 46, pairs of 23 – half from sperm, half from egg – contains 20,000 genes Genes – each human cell contains about 1 million genes – a gene, or group of genes, decides a trait

© Goodheart-Willcox Co., Inc. Dominant and Recessive Traits Dominant traits always show in a person even if only one gene of the pair is inherited for that trait Dominant traits Recessive traits typically do not show in a person unless both genes for the trait are inherited Recessive traits – one from each parent – person who inherits only one recessive gene for a trait becomes a carrier of that trait

© Goodheart-Willcox Co., Inc. Sex Chromosomes Sex chromosomes determine genetic sex of baby – XX female ovum always carries only X chromosomes – XY male sperm can carry either X or Y chromosome boys’ sex-linked traits are determined only by their mothers

© Goodheart-Willcox Co., Inc. Objective List the three different types of multiple pregnancies.

© Goodheart-Willcox Co., Inc. Multiple Pregnancy Multiple pregnancy occurs when two or more babies develop in the same pregnancy Multiple pregnancy continued

© Goodheart-Willcox Co., Inc. Multiple Pregnancy Fraternal children develop from two or more ova Fraternal – most common – each baby has own chorionchorion Identical children develop from same ova and sperm Identical Mixed types of pregnancy must include fraternal and identical babies

© Goodheart-Willcox Co., Inc. What Do You Think? How can parents help identical twins maintain separate identities while still nurturing a close sibling relationship?

© Goodheart-Willcox Co., Inc. Objective Describe the three main stages of prenatal development.

© Goodheart-Willcox Co., Inc. Stages in Prenatal Development Prenatal development takes place between conception and birth Prenatal development – germinal stage – embryonic stage – fetal stage

© Goodheart-Willcox Co., Inc. Germinal Stage Germinal stage is the first stage of development Germinal stage continued

© Goodheart-Willcox Co., Inc. Germinal Stage Amnion is a fluid-filled sac that surrounds the baby in the uterus Amnion Placenta is an organ filled with blood vessels that nourish the baby in the uterus Placenta Umbilical cord is a cord that connects the baby to the placenta Umbilical cord

© Goodheart-Willcox Co., Inc. Embryonic Stage Embryonic stage is the second stage of development, lasts about six weeks Embryonic stage – most crucial to development – baby is called an embryoembryo – development of most body systems – heart begins to beat – cartilage is present before bones form cartilage – substances pass from mother’s placenta through the umbilical cord

© Goodheart-Willcox Co., Inc. Fetal Stage Fetal stage is the third stage of pregnancy, lasts from about nine weeks after conception until birth Fetal stage – bone starts to replace cartilage – baby is known as a fetusfetus continued

© Goodheart-Willcox Co., Inc. Fetal Stage During the fetal stage, – all parts of the body mature – overall size increases quickly – hear heartbeat in the third month – quickening begins between the fourth and fifth months quickening continued

© Goodheart-Willcox Co., Inc. Fetal Stage Age of viability is the age at which a baby could survive if born, 28 weeks Age of viability – still need extensive medical care – better chance of survival each week the baby is not born During last two months of pregnancy, – inner layer of lungs produces substance that allows for breathing air – receives immunities from mother in the ninth month

© Goodheart-Willcox Co., Inc. What Do You Think? Pregnancies that end before 20 weeks are considered a miscarriage, resulting in no record of the life, such as a birth or death certificate. How do you think this impacts a parent after the loss of a wanted pregnancy?

© Goodheart-Willcox Co., Inc. age of viability. Age at which most babies could survive if they were born (28 th week of pregnancy). amnion. Fluid-filled sac that surrounds the baby in the uterus. cartilage. Soft, elastic, flexible tissue that provides structure for the body. Glossary of Key Terms

© Goodheart-Willcox Co., Inc. cell. Smallest unit of life that is able to reproduce itself. chorion. Membrane that surrounds the baby in the uterus. chromosomes. Threadlike structures that carry genes in living cells. conception. Union of the ovum and sperm cells. Glossary of Key Terms

© Goodheart-Willcox Co., Inc. dominant traits. Traits that always show in a person even if only one gene of the pair is inherited for that trait. embryo. Medical term used to describe the unborn baby in the embryonic stage of development (week 3 through 8 of pregnancy). Glossary of Key Terms

© Goodheart-Willcox Co., Inc. embryonic stage. Second stage of prenatal development, lasting about six weeks. fallopian tubes. Two hollow tubes that connect to the uterus and have fingerlike projections that reach toward each ovary. fetal stage. Third stage of pregnancy, lasting from about nine weeks after conception until birth. Glossary of Key Terms

© Goodheart-Willcox Co., Inc. fetus. Medical term used to describe the unborn baby in the fetal stage of development (week 9 until the end of pregnancy). fraternal. Term used to describe children from multiple pregnancies who develop from two or more fertilized ova and differ in genetic makeup. Glossary of Key Terms

© Goodheart-Willcox Co., Inc. genetic factors. Traits that are passed through the genes. germinal stage. First stage of prenatal development, lasting about two weeks after conception. identical. Term used to describe children from multiple pregnancies who develop from one fertilized ovum and have the same genetic makeup. Glossary of Key Terms

© Goodheart-Willcox Co., Inc. multiple pregnancy. Pregnancy in which two or more babies develop. ovum. Female sex cell; also called egg. placenta. Organ filled with blood vessels that nourish baby in the uterus. prenatal development. Development that takes place between conception and birth. Glossary of Key Terms

© Goodheart-Willcox Co., Inc. quickening. Movements of the fetus that can be felt by the mother. recessive traits. Traits that typically do not show in a person unless both genes for the trait are inherited. sperm. Male sex cell. umbilical cord. Cord that connects the baby to the placenta. Glossary of Key Terms

© Goodheart-Willcox Co., Inc. uterus. Organ in which the baby develops and is protected until birth. zygote. Single cell formed at conception; also called fertilized egg. Glossary of Key Terms