monday, may 5 “b” day

Section 19.1 Development Before Birth

Monday, May 5 “B” Day

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Pregnancy, Birth, Childhood


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Objectives

Summarize the events that occur during the first week after fertilization.

Describe the structures that protect and nourish the embryo and fetus.



12 Myths About Pregnancy1. You can determine your baby’s gender by the

position of sexual intercourse and you can predict it by how you are carrying.

• The gender of your baby is determined by the father; more specifically, if sperm carrying an X-chromosome fertilizes the egg, the baby will be a girl and if the sperm carrying a Y-chromosome fertilizes the egg, a boy will result. The position of intercourse has no clear effect on which type of sperm (X or Y) successfully fertilizes the egg.

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12 Myths About Pregnancy Cont’d

2. The worse the morning sickness, the more likely it is you're having a girl.

• Most experts believe this is truly a myth. However, several studies have found that among women with severe morning sickness bad enough to require admission to the hospital, slightly more than half (53% to 56%) delivered girls, so perhaps there is some truth to this idea. Then again, even among those with the worst morning sickness, the male and female offspring were nearly 50-50 and whether this applies to milder cases is unknown.

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12 Myths About Pregnancy Cont’d

3. If you raise your arms above your head while pregnant (as when you are hanging up clothes on a clothesline), the baby will get the cord wrapped around its neck.

• Up to 25 percent of fetuses have the umbilical cord wrapped around the neck; it is the baby's activity in the womb and, perhaps, bad luck, not the mother's activities during pregnancy that determine whether the cord is wrapped around the baby's neck. Another important risk factor is a long umbilical cord, but, again, that may have more to do with fetal activity and is not something a pregnant woman can prevent. The good news is that nearly all of these babies develop normally and are successfully delivered.

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12 Myths About Pregnancy Cont’d4. If you get a lot of heartburn during pregnancy, your baby will have a lot

of hair.• Heartburn is common during pregnancy because, as the stomach is

pushed higher by the growing baby and the expanding uterus, it becomes easier for acid to move backwards (or "reflux") from the stomach into the lower esophagus. Acid is irritating to the esophagus and causes the discomfort we know as heartburn. Remaining upright after eating, sleeping with the head of the bed at a slight elevation, and antacid medications (many of which are considered safe during pregnancy) can be helpful.

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12 Myths About Pregnancy Cont’d5. Avoid sleeping on your back or, always sleep on your left side.• During the later stages of pregnancy, the uterus and baby may be large

enough to press on the large vein, the inferior vena cava, and reduce flow of blood from the lower body (and uterus) back to the heart. But this tends to matter only in certain circumstances such as prolonged labor, if blood pressure is high, if the kidneys are not functioning properly, or if there is a problem with fetal development. In those situations, lying on the left side may be somewhat helpful, but for normal, healthy women in the midst of a routine, successful pregnancy, the best position for sleeping is the one that's most comfortable.

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12 Myths About Pregnancy Cont’d6. To keep your unborn child safe, avoid sex and exercise during pregnancy• Within the bounds of common sense, there is no recommendation to

avoid exercise or sex during pregnancy. The baby is protected in the uterus so that sex is unlikely to cause problems. Similarly, moderate exercise is not prohibited during pregnancy, and is often recommended. Because excessive body heat can be harmful to a developing fetus, exercising in hot weather should be avoided. And if your pregnancy is complicated by bleeding, pre-term labor or other problems, your obstetrician may recommend that you avoid sex as well as certain exercises.

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12 Myths About Pregnancy Cont’d7. You should not touch your cat while pregnant.• This myth is close to the truth but still untrue. The recommendation

regarding cats during pregnancy is due to toxoplasmosis, a parasite that can cause serious infections in humans and deformities in the developing fetus. Infection can follow handling of cat litter because it can be found in the stool of cats, so pregnant women are advised not to handle cat litter. However, no other activities are prohibited – feeding or petting your cat and allowing it to sit in your lap are considered perfectly acceptable while pregnant. And the risk of getting toxoplasmosis from your cat can be lowered even further if your cat has tested negative for this parasite or is an indoor cat that eats only store-bought canned or dry food.

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12 Myths About Pregnancy Cont’d8. If you are pregnant, you cannot have X-rays and should avoid microwaves

and computer terminals.• While unnecessary radiation exposure should generally be avoided while

pregnant, if there is a good reason for a chest X-ray (for example), the amount of radiation exposure to the fetus is minimal—in fact, according to some experts, you might receive a similar amount of radiation by taking several commercial airplane flights (due to cosmic radiation from the sun and other stars). There is no evidence that modern microwave ovens or computer terminals expose women or their fetuses to harmful radiation.

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12 Myths About Pregnancy Cont’d9. Don't take a bath if you're pregnant.• Apparently, concerns about contracting an infection that could spread

from the vagina, through the cervix, into the womb led to recommendations to avoid bathing. However, there is no well-established risk known to be associated with bathing during pregnancy. The water should not be too hot, since raising body temperature above 101 degrees F may cause problems. And there may be times to avoid bathing altogether, for example, if your water has broken or there is bleeding.

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12 Myths About Pregnancy Cont’d10. If the weather is stormy or the moon is full, you are more likely to go into

labor, even if you are weeks away from your due date.• While believers may never be convinced otherwise, studies have

demonstrated no increased incidence of labor based on the weather or the phase of the moon. Never mind the fact that even if this were true, there's nothing you could do about it! In fact, labor is triggered by a complex series of hormonal signals with no known connection to atmospheric conditions or the weather.

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12 Myths About Pregnancy Cont’d11. Avoid spicy foods—they can trigger labor before you're ready.• Scientific evidence suggests that labor is triggered by biological signals,

some of which are well understood and others that remain uncertain. For a routine pregnancy, as long as you eat a well-balanced diet, there is no evidence that what you eat has any effect on your delivery date.

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12 Myths About Pregnancy Cont’d12. Avoid bumpy car rides—they can trigger labor (or being bumped in the

abdomen can trigger labor, or lifting groceries).• Minor bumps, taps and jolts, as in a bumpy (but "on-road") car ride is

highly unlikely to trigger labor. The uterus and surrounding fluid provide ample cushioning and protection from minor trauma. Of course, major injury, as in a car accident or a fall, may complicate pregnancy, including inducing pre-term labor.

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TEEN PREGNANCYVIDEO

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EXERCISETIME!!!

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The Beginning of the Life Cycle• Once a couple has decided to start a family, they

may try to conceive, or get pregnant.

• In a fertile woman’s body, about once a month an egg enters one of the fallopian tubes and begins its journey to the uterus.

• If the egg is on its way to the uterus, a sperm may fertilize it. This moment of fertilization is also called conception.


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FertilizationThe Beginning of the Life Cycle

• Only a few hundred sperm of the hundreds of millions that enter the vagina usually make it to the egg, and only one can fertilize it.

• In the first week after fertilization, the fertilized egg undergoes many cell divisions and travels to the uterus.


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The Zygote• The united egg and sperm is called a zygote

(ZY goht).• Within 36 hours, while the zygote is still traveling

through the fallopian tube, it begins to divide.

The Beginning of the Life Cycle


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Cell Division• The original cell divides to make two cells.

• The two-celled embryo divides into four cells, and so on, until the embryo is made up of dozens of cells.



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The Blastocyst• From the two-cell stage until about nine weeks

after fertilization, the growing structure is called an embryo (EM bree oh).

• About five days after fertilization, the structure, called a blastocyst (BLAS tuh sist), is no longer a solid mass of cells, but a sphere of cells surrounding a hollow center.



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Implantation• Once the blastocyst forms, it begins to attach itself

to the wall of the uterus.

• The process of attachment is called implantation.



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Uterus

Implantation

Zygote

Blastocyst

Fallopian tube

Cell division

Fertilization

Ovary


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Wall of uterus

Amniotic fluid

Cervix

Vagina

PlacentaThis structure lines part of the wall of the uterus during pregnancy and nourishes the embryo with substances from the mother’s blood.

Amniotic sacThe amniotic fluid contained in this sac cushions the embryo from shock and helps keep the embryo’s temperature constant.

Umbilical cordAn umbilical cord carries nutrients and oxygen from the placenta to the embryo, and carries wastes away.


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Development in the Uterus• While the embryo grows, several other structures

also develop.

• These structures—the amniotic sac, placenta, and umbilical cord—protect and nourish the developing embryo, and later the fetus.


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Amniotic Sac• Soon after implantation, a fluid-filled bag of thin tissue

called the amniotic sac (am nee AHT ik) develops around the embryo.

• Inside the sac, the embryo floats in amniotic fluid.


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Placenta• The attachment holding the embryo to the wall of

the uterus develops into a structure called the placenta.

• Within the placenta, oxygen and nutrients move from the mother’s blood into tiny blood vessels that lead to the embryo.


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Umbilical Cord• About 25 days after fertilization, a cordlike structure

called the umbilical cord (UM BIL ih kul) develops between the embryo and the placenta.

• Blood vessels in the umbilical cord carry nutrients and oxygen from the placenta to the embryo and wastes from the embryo to the placenta.


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The Growing Embryo• During the first two months of development, the major

body systems and organs start to form in the embryo.

• By the end of eight weeks, the embryo is about an inch long and has recognizable external features.


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The Fetus• From the third month until birth, the developing

human is called a fetus.

• During the third to sixth month, the fetus begins to move and kick.

• By the end of the ninth month, the fetus is ready to be born.


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Conception Pictures

http://www.webmd.com/baby/slideshow-conception


Life’s Greatest Miracle

• http://www.pbs.org/wgbh/nova/miracle/program_adv.html

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http://www.pbs.org/wgbh/nova/miracle/program_adv.html

http://www.pbs.org/wgbh/nova/miracle/program_adv.html


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Vocabulary

zygote The united egg and sperm.

embryo The stage of human development from the two- cell stage until about nine weeks after fertilization.

blastocyst A hollow, spherical structure made up of about 50-100 cells, formed when a zygote divides and grows.

implantation The process in which the blastocyst attaches itself to the wall of the uterus.

amniotic sac A fluid-filled bag of thin tissue that develops around the embryo.


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Vocabulary

umbilical cord The cordlike structure that connects the embryo and the placenta.

fetus The stage of human development from the third month after fertilization until birth.

placenta The structure that holds the embryo to the wall of the uterus.


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Staying Healthy During PregnancyGetting proper nutrition and exercise and avoiding drugs and environmental hazards are especially important both before and throughout pregnancy.


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Avoiding Environmental Hazards• X-rays The radiation from X-rays can harm a developing

embryo or fetus.

• Lead If a pregnant woman lives in a home built before 1978, she should contact her state health department for information on getting her home tested for lead.

• Mercury Pregnant women should eat commercially caught fish only once a week, and should not eat swordfish or shark.

• Cat litter Cat feces can contain a parasite that is especially dangerous to a developing fetus.


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Prenatal Care• Besides taking care of herself at home, a woman

also needs to plan for prenatal care, or medical care during her pregnancy.

• Her doctor visits should be under the supervision of an obstetrician, a doctor specialized in pregnancy and childbirth.

• The chances of having a healthy baby greatly increase if the mother visits her doctor or clinic for regular checkups throughout pregnancy.


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Monitoring Tools• Ultrasound High-frequency sound waves, or

ultrasound, are used in most pregnancies to create an image of the developing fetus.

• Chorionic Villus Sampling Around the eighth week of pregnancy, some women will undergo a test called chorionic villus sampling, or CVS.

• Amniocentesis Another test that may be done around the fourteenth to sixteenth week of pregnancy is amniocentesis (am nee oh sen TEE sis).


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• Ectopic pregnancy In very rare cases of ectopic pregnancy, the blastocyst implants in the fallopian tube or elsewhere in the abdomen, instead of in the uterus.

Complications

• Miscarriage The death of an embryo or fetus in the first 20 weeks of pregnancy is called a miscarriage.

• Preeclampsia Also called toxemia, preeclampsia (pree ih KLAMP see uh) is characterized by high blood pressure, swelling of the wrists and ankles, and high levels of protein in the urine.

• Gestational Diabetes Diabetes that develops in pregnant women is called gestational diabetes, and is marked by high blood sugar levels.


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The Birth Process• A certified nurse-midwife is a nurse who is trained

to deliver babies.

• The birth process begins when the muscular walls of the uterus begin a series of contractions that will push the fetus out of the mother.

• Birth takes place in three stages• labor• delivery of the baby • delivery of the afterbirth


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Labor• The work performed by the mother’s body to push

the fetus out is called labor.

• Labor for a first child may last from about 2 to 24 hours or longer.

• Near the end of this first stage, the amniotic sac breaks, and the cervix becomes softer and wide enough or the fetus to pass through.

The Birth Process


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The Birth Process


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Delivery of Baby• Stage two involves the actual birth, or delivery, of the

baby.

• This stage can take from half an hour to more than two hours.

• Once the baby is out• the doctor clamps and cuts the umbilical cord• the baby’s nose and mouth are suctioned • eye drops are put in the baby’s eyes • an injection of vitamin K is given

The Birth Process


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The Birth Process


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Delivery of Afterbirth• The third stage involves contractions of the uterus that

push out the placenta, also called the afterbirth.

• This stage typically takes about 15 to 30 minutes.

The Birth Process


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The Birth Process


Thursday, May 8 “A” Day

• Finish Pregnancy & Birth Notes• Take Chapter 19 Quiz• Watch “Life's Greatest Miracle”

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Complications at Birth• Some complications result in a surgical delivery or

premature birth.

• Low birthweight and the birth of more than one baby also may cause complications.

• A stillbirth occurs when a fetus dies and is expelled from the body after the twentieth week of pregnancy.


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Surgical Delivery• Sometimes delivery through the cervix and vagina is

not possible because of• the position of the fetus in the uterus

• the narrowness of the mother’s hips

• illness

• A cesarean section (suh ZEHR ee un) is a surgical method of birth.

• other conditions

• First the doctor makes an incision in the lower abdomen into the uterus, then he or she removes the baby and placenta.


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Premature Birth• Delivery of a live baby before the 37th week of

pregnancy is called premature birth.

• The lungs of a premature baby are usually not fully developed.

• The baby may have additional problems if other organs aren’t fully developed.

• A premature baby may receive care in an incubator.


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Low Birthweight• A newborn that weighs less than 5.5 pounds at birth is

considered to have low birthweight.

• Premature and low-birthweight babies face an increased risk of health problems as newborns, chronic lifelong health problems, and even death.


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Multiple Births• The delivery of more than one baby—for example,

twins, triplets, or quadruplets—is called a multiple birth.

• These births carry greater risk to the mother and babies, and are closely monitored by doctors.


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Identical Twins• Twins that develop from a single fertilized egg, or

zygote, are called identical twins.

• Because they develop from identical embryos, identical twins have the same inherited traits and are the same sex.


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Identical Twins

A sperm fertilizes a single egg.

Early in development, the embryo splits and forms two

identical embryos.

Identical twins result.


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Fraternal Twins• Sometimes two eggs are released from the ovary

and are fertilized by two sperm.

• Fraternal twins are no more alike than any other siblings, and they may or may not be the same sex.


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Fraternal Twins

Two different sperm fertilize two eggs.

Each of the fertilized eggs develops into an embryo.

Fraternal twins result.


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Triplets or MoreTriplets, quadruplets, and other multiple births are less common than twins.


Life’s Greatest Miracle

• http://www.pbs.org/wgbh/nova/body/life-greatest-miracle.html

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http://www.pbs.org/wgbh/nova/body/life-greatest-miracle.html

http://www.pbs.org/wgbh/nova/body/life-greatest-miracle.html

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