1. Chapter 4 Pregnancy Unit 2
Prenatal Development
Chapter 4 Pregnancy
Unit 2

2. What you should know when we are done with this chapter!
Describe what happens during conception
Explain how genetic factors affect prenatal development
Describe how a person inherits traits through genes
List the three different types of multiple pregnancies
Describe the three main stages of prenatal development

3. The prenatal period lasts from about 270-280 days
The prenatal period lasts from about days. It is the shortest stage in the life span.

4. What is Pregnancy?
The process through which a new human prepares to enter the world.

5. Conception:
Cell- the smallest unit of life that is able to reproduce itself. Life begins with the joining of two separate cells one from the male and one from the female
Sperm- the male germ cell
Ovum or egg- the female germ cell
Conception- the joining of these two cells- at conception, ovum and sperm combine to form a single cell called a zygote or fertilized egg

6. Egg information
Eggs produced and stored by the woman’s ovaries in a small sac called the follicle. Each month hormones cause some follicles to grow and fill with fluid. Around the middle of the menstrual cycle, one ovum is released from the follicle and the other follicles become inactive- yet sometimes more than one ovum or egg is released. The release of the ovum from the ovary is called ovulation.

8. When the egg is released it travels to the fallopian tubes- these are two hollow tubes that extend from the right and left sides of the uterus. Once inside the FT- the ovum or egg is ready and available to be joined by a sperm. Semen may carry over 100 million sperm as it enters the woman. Many of the sperm do not survive. Sperm may meet the ovum at any point. Only one sperm successfully enters or fertilizes the egg. Once one sperm enters- no others can enter and CONCEPTION HAS OCCURRED AND A ZYGOTE IS FORMED!

9. Uterus- the organ is which the baby develops and is protected until birth

10. GENETICS- traits passed through genes
GENETICS- traits passed through genes. These affect ALL stages of development.
Because of genetics the unborn baby will:
come to look like other family members
likely have the same interests
have similar personalities

11. Genetics affect the prenatal period- and sets forth the blueprint for the developing fetus. These blueprints will give information to the fetus later in life.
For example- during the prenatal period- the blueprint is put down whether the baby boy will become bald later in life- sorry Rogaine!

12. Chromosomes and Genes
Each baby is given 23 pairs of chromosomes- for a total of 46
½ from mom and ½ from dad- What are they? threadlike structures that carry genes in living cells.

14. Each chromosome contains about 20,000 genes - these genes determine traits each person will have
Humans cells have about a million genes- sometimes one gene will determine a trait- other times it a group of genes that do

15. Traits
DOMINANT TRAITS- traits that always show in a person even if only one gene of the pair is inherited for that trait.
RECESSIVE TRAIT- traits that typically do not show in a person unless both genes for the trait are inherited

17. Sorry, I couldn’t help myself!

18. Sex Chromosomes- 22 of the chromosomes the same in men and women- the last pair is the sex chromosome

19. How are we doing? Did we? Describe what happens during conception
Explain how genetic factors affect prenatal development
Describe how a person inherits traits through genes
List the three different types of multiple pregnancies
Describe the three main stages of prenatal development

20. What can be affected by sex chromosomes:
Height
Eye color

21. Multiple Pregnancy-If 2 or more babies develop in the same pregnancy
becoming more common due to fertility drugs

23. Multiples According to the text: frequency of twins 1 in 35
3 or more babies in the same pregnancy 1 in 540
Dr.’s often concerned with the health of multiples
Most of these babies are born early and are underweight
Risks can include:
severe vision issues
hearing issues
mental and developmental disabilities
twins are also 5 times more likely to die in their first year (triplets 10 times)

24. Fraternal Births- most common when multiple babies develop from two or more ova- each fertilized with a different sperm
Fraternal Facts:
may or may not look alike
may or may not be the same gender
each fraternal twin has their own chorion- a membrane that surrounds the baby in the uterus
no more similar than any other sibling

25. Identical Births-children develop from a single ovum that was fertilized by a single sperm. This happens early on and Dr.’s do not know why it splits.

26. Identical Facts:
if ovum does not totally split, the babies will be conjoined
identical babies have the identical genetic makeup
they are the result of one fertilized egg
similar in appearance
fingerprints, footprints, and palm prints are similar-but not exact

27. Mixed Types- can be both identical and fraternal if three or more children are born. In order to be a mixed type, the babies must be fraternal and identical. It works with quadruplets as well. There could even be two identical pairs.

28. Stages in Prenatal Development:
Many things happen between conception and birth. All these changes are called prenatal development. There are 3 stages:
Germinal/Zygote
Embryonic/Embryo
Fetal/Fetus

29. Germinal Stage: this is the first stage
Germinal Stage: this is the first stage. Conception starts the beginning of this stage.

30. Germinal/Zygote highlights:
Lasts the first 2 weeks of pregnancy.
The fertilized egg remains a single cell for about a day and ½
By day 3 it is a hollow ball of 32 cells
This ball of cells then enters the uterus and floats freely
About days after conception the ball of cell embed in the uterus wall
The cells continue to divide
The chorion and the amnion(amniotic sac) begin to form
The placenta begins to develop against the wall of the uterus

31. Germinal/Zygote highlights:
The umbilical cord grows out of the developing child at the site of the navel and connects with the placenta
The umbilical cord contains three blood vessels that connect the child with the placenta
The placenta will develop it will begin to nourish the baby, remove the baby’s wastes, exchange gases between mom and baby
It also provides hormones for the baby
This stage ends when the baby can receive nourishment from the mom

32. The Embryonic Stage this is the 2nd stage of prenatal development
The Embryonic Stage this is the 2nd stage of prenatal development. Experts say that this is the most important stage since almost all body systems develop during this stage.

33. Embryo Highlights Lasts until the 8th week
When this stage ends, the embryo looks like a small human
The embryo has tiny arms, legs, fingers, toes, and a face
All major organs such as heart, brain, and lungs are there
Heart begins beating
No bones only cartilage
Baby now receives both good and bad substances from the mom through the umbilical cord
Baby’s body parts are developing quickly, so passing harmful substances to the child can affect them for life
The mom’s diet needs to full of vitamins and nutrients
Mom should avoid: alcohol, drugs, excess caffeine, smoke, and x-rays

34. Fetal Stage: this is the 3rd stage
Fetal Stage: this is the 3rd stage. This is when the bone starts to replace cartilage. This stage starts about week 9 up to delivery.

35. Fetal highlights: All body parts start to mature
Overall size increases
By the 4th month the fetus has grown enough to give the mom’s growing abdomen a pregnant look
Two major milestones- in the 3rd month the parents may be able to hear the heart of the baby and by the 4th -5th month the mom can start to feel the baby(quickening)
The fetus can turn, swallow, and even suck its thumb

36. Fetal highlights:
Another important milestone- 28 weeks/7 months= the age of viability- when the fetus has a strong chance of surviving outside of the mom if it were to be born now
They still may need special help- yet they have a strong chance of survival
Last 2 months the lungs become stronger and the baby becomes larger
9th month the baby receives immunities from the mom- ex: if mom had chicken pox- the baby will have the chicken pox immunity from the mom
Finally the baby will start to turn head down to prepare for birth

38. So, did we get it all? Describe what happens during conception
Explain how genetic factors affect prenatal development
Describe how a person inherits traits through genes
List the three different types of multiple pregnancies
Describe the three main stages of prenatal development