CHAPTER 19PRENATAL DEVELOPMENT AND
BIRTH
LESSON 1- THE BEGINNING OF THE LIFE CYCLE
In this Chapter we will discuss events from fertilization to birth
Describe Prenatal care
Indentify Prenatal risks
PRENATAL DEVELOPMENT We begin life from a single cell
During the 9-month period, the cell will divide millions of times
It will form tissues, organs, body systems, & characteristics of the person it will become
CONCEPTION AND IMPLANTATION Fertilization: Union of egg cell(female) and the sperm cell (male) Also known as conception
Zygote: Fertilized egg cell Takes about 4 days to reach the uterus Once formed, a protective membrane surrounds it to
prevent more sperm from entering the ovum Divides many times (mitosis-cell division) to form a
cluster of cells with a hollow space in the middle After 5 days, the zygote reaches the uterus & is called
Blastocyst
Implantation: the zygote attaches to the uterine wall Takes about 10 days to implant The endometrium tissue protects & nourish the egg
EMBRYONIC GROWTH Embryo: A cluster of cells following implantation Called an embryo for about 8 weeks
3 layers of tissue formed as cell continues dividing:
Respiratory & digestive system Muscles, bones, blood vessels, & skin Nervous system, sense organs, mouth
EMBRYONIC GROWTH
Amniotic Sac: Thin membrane formed to surround the developing embryo
Amniotic Fluid: Fluid in the amniotic sac Acts as a shock absorber Insulates from temperature changes Allows fetal movement Permits proper lung development Constantly circulated by the baby swallowing
& inhaling existing fluid & replacing it through exhalation & urination.
EMBRYONIC GROWTH
Placenta: Provides nutrition, excretion, & immunity Blood rich tissue made by embryonic cells &
the tissue from the mother
Umbilical Cord: Tube which nutrients & oxygen pass from the
mother’s blood to the embryo Carries waste products from embryo to
diffuse into the mother’s blood
FETAL DEVELOPMENT
Conception to birth is usually about 9 months Divided into (3) 3-month periods called
Trimesters
First Trimester: 0-14 weeks
Second Trimester: 15-28 weeks
Third Trimester: 29 weeks to birth
Let’s look at pages 488-489 to see what’s going on in these stages of fetal development!
STAGES OF BIRTH
The last few weeks of pregnancy, the baby’s head moves to the lower part of the uterus
95% of the time it rests on the cervix
Dilation: Cervix stretches because of mild contractions (Labor) Contractions break the amniotic sac (water breaks) Cervix dilated about 3 cm Contractions are about 5-20 minutes apart
STAGES OF BIRTH Birth: Contractions are 1-3 minutes apart (active labor) Cervix 8 to 10 cm Stage lasts minutes to hours Baby passes through the birth canal Cries to clear lungs and amniotic fluid Umbilical cord cut
Apgar Test: Routine diagnostic test to determine the physical condition of the baby
Appearance Reflex Activity Pulse and respiration
AFTERBIRTHCONTRACTIONS CONTINUE TO PUSH OUT THE PLACENTA
15-30 MINUTES LATER
Umbilical Cord Placenta
HOW ARE TWINS BORN?
Single egg fertilized by single sperm that divides to form 2 embryos
Same genetic info
Same gender
Ovaries release 2 eggs
Separate sperm fertilize each egg
Different genetic makeup
May or may not be the same gender
Identical Fraternal
1 OUT OF 87 BIRTHS RESULT IN TWINS (1/3 BEING IDENTICAL)1 OUT OF 7570 ARE TRIPLETS1 OUT OF 658,00 ARE QUADRUPLETS1 OUT OF 57, 290, 000 ARE QUINTUPLETS1 IN 50,000 ARE BORN CONJOINED
PAIN RELIEF DURING PREGNANCY
Anesthetic: Local-numbs the vagina Regional-eases the pain of contractions Spinal: Injection into the spine (works immediately) Epidural: Tube inserted into the back for medicine to be released
throughout labor General: Puts patient to sleep (used mainly in C-sections)
Birthing Tube: Warm soak Promotes deep relaxation Reduces anxiety Relieves pain
Lamaze: Used since the 1950’s Started mainly with breathing exercises Goal is to increase the mother’s confidence in their ability to give
birth
COMPLICATIONS DURING PREGNANCY
Miscarriage: Spontaneous expulsion of the fetus before the 20th week
Still Birth: Death of a fetus after week 20 of pregnancy
Ectopic Pregnancy: Zygote implants in the fallopian tube, abdomen, ovary, or
cervix Egg cannot get to the uterus because of inflammation or
scar tissue resulting from a STD Stone baby
Preclampsia: Toxemia prevents the placenta from getting enough blood
High Blood pressure and high protein in the urine Bed rest, meds, or hospitilization
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