Health 21.1

Chapter 21
Lesson 1

Contraception, Pregnancy, and Birth

​After this lesson, you will be able to

-describe how genes from both biological parents influence a person’s traits

-explain what happens during conception

-outline what happens during the stages of prenatal development

-explain the importance of prenatal care

-identify behaviors that help or harm the developing baby

-describe what happens during each stage of childbirth

When two people reproduce, their genetic material combines to create a new individual. This new individual has characteristics from both biological parents. This is because the individual has chromosomes from each biological parent.







A chromosome is a package of genes, which contain the blueprint for the structure and function of your cells. Genes are made of deoxyribonucleic acid (DNA).

​Conception, Pregnancy, and Birth

Multiple Choice

Genes are made of ___

• RNA

• DNA

• CNA

• NDA

Human cells have 23 pairs of
chromosomes, or 46 total
chromosomes. Of these, 22
pairs of chromosomes possess
similar genetic material. This
genetic material influences many of
your characteristics, including your
eye color, hair color, and risk for
certain diseases.

Chromosomes

Dominant genes always cause certain characteristics in a child. Recessive genes only cause certain characteristics if the child inherits a recessive gene from each parent.


A female has two X chromosomes in each cell, and a male has one Y chromosome and one X chromosome in each cell.

Chromosomes

Multiple Choice

A female has ____ X chromosomes in each cell

• 4

• 3

• 2

• 1

Multiple Choice

A male has ____ Y chromosome and _____ X chromosome in each cell

• 4

• 3

• 2

• 1

Humans reproduce through sexual intercourse. During intercourse, the sperm and egg combine in a process called fertilization. The moment at which the sperm and egg combine is called conception.



Conception usually involves the union of a single sperm with a single egg.




Sometimes there will be two eggs in the fallopian tubes which will result in fraternal twins.

Fertilization and Conception

Human gestation, or the period of time

between conception and birth, is about

nine months long. Most babies are

born 36–40 weeks after fertilization.

Pregnancy can be divided into several

stages, and a person’s behaviors

during pregnancy influence the health

of the developing baby.

Fertilization and Conception

Multiple Choice

Most babies are born ____–____ weeks after fertilization.

• 40-48

• 24-30

• 32-36

• 36-40

The germinal stage of pregnancy starts at the time of conception and lasts about two weeks. This is when the sperm and the egg combine to form a zygote. During the germinal stage, the zygote begins to divide in order to implant into the uterine wall. Once implantation is complete, the embryonic stage begins.

The Germinal Stage

The embryonic stage of prenatal development lasts for about six weeks and is a critical period.



During this time, the embryo begins to form the various tissues and organs that make a human.



Systems that will help the embryo develop also take shape during this stage.

The Embryonic Stage

In the Embryonic Stage there are several different things that occur, such as the following:



1. The placenta forms from the chorion and amnion

2. The placenta develops in helping support the embryo

3. The umbilical cord forms, which is where the embryo gets its nutrients and oxygen


The embryo also begins to form various tissues and organs.

The Embryonic Stage

The 9th week of pregnancy marks the beginning of the fetal stage. At this stage, the baby is now called a fetus.

By the 4th month, the fetus has grown enough that the pregnant person has a visible bump in the abdomen.

After 9 months, most of the organs, bones, and muscles of the fetus have completed their development.

The lungs and liver are the last organs to complete development. Once they develop, the baby is ready to be born.

The Fetal Stage

Multiple Choice

By what month, the fetus has grown enough that the pregnant person has a visible bump in the abdomen.

• 4th

• 6th

• 8th

• 2nd

During pregnancy, a person should receive prenatal care, or care for the developing baby and pregnant person before birth.

This involves making regular visits to an obstetrician/gynecologist (OB/GYN), who specializes in pregnancy, labor, and delivery.

On the first visit, the doctor will ask for the date of the person’s last menstrual period to estimate the expected birth date, or due date.

Prenatal Care

Pregnancy is divided into stages the doctors refer to as trimesters.

first trimester – conception to 12 weeks

 second trimester – 13 to 27 weeks

third trimester – 28 to 40 weeks.

Stages of Pregnancy

Multiple Choice

Pregnancy is divided into what ?

• sismesters

• quadmester

• trimester

• semester

Multiple Choice

These weeks are considered to be what trimester, 13-27 weeks

• first

• second

• third

• none

The actions a person takes during pregnancy affect the health of a developing baby.

For example: eating well promotes personal health and the health of the baby.
Most pregnant people should add about 300 calories to their daily diets.
Gaining about 25–35 pounds is normal during pregnancy.

Healthy Behaviors During Pregnancy

People who are pregnant should avoid certain substances. These substances include the following:

1. Alcohol- can cause serious issues such as fetal alcohol syndrome

2. Nicotine- increases the risk of sudden unexpected infant death (SUIDS) and sudden infant death syndrome (SIDS)

3. Drugs- these are not only harmful for the babies development but they can be born dependent on these drugs

Healthy Behaviors During Pregnancy

People who are pregnant should also avoid certain foods. Examples of foods they should avoid are:

1. Foods that contain mercury, like canned tuna or any fish

2. Unpasteurized products; such as cheese, yogurts, and several other dairy products

3. Raw or undercooked meats; such as meat, eggs and fish can transmit harmful diseases to babies

Healthy Behaviors During Pregnancy

Multiple Choice

Substances that a woman consumes throughout her pregnancy affects the baby

• True

• False

As a baby’s due date approaches, hormones prepare the pregnant person’s body for childbirth, then trigger and coordinate labor and the delivery of the baby.

For example, the baby may be born in a hospital or birthing center.

The doctor may administer epidural anesthesia (pain medication injected into the spinal cord of the pregnant person).

The baby may be delivered vaginally or through a cesarean section (surgery to remove the baby C-section).

The doctor may make an incision called an episiotomy to help the baby pass through the birth canal.

Child Birth

A process called labor pushes a baby out of the pregnant person’s body and into the world.

There are three stages of labor:

1st stage: In the first stage of labor, contractions of the uterus cause the cervix to thin (efface) and stretch (dilate). This opens the cervix and makes room for the baby to pass from the uterus into the vagina.

2nd stage: In this stage, the uterine and abdominal muscles push the baby into the vagina and out of the body.

3rd stage: The placenta is delivered in the final stage of labor.

Labor

Multiple Choice

This process is when a woman pushes a baby out of the pregnant person’s body and into the world.

• birth

• labor

• baby pushing

• fetal stage