From Conception to Birth Period of the Zygote Period of the Embryo Period of the Fetus

From Conception to BirthPeriod of the Zygote Period of the EmbryoPeriod of the Fetus

The experience of pregnancy1. Physical complaints such as

nausea are common.2. Normal weight gain is about

thirty pounds and is dispersed in organs, baby, and bodily fluid.

3. Changes in the woman's body bring mixed feelings.

Period of the ZygoteBegins when egg is fertilized in the fallopian tube.

Period of rapid cell divisionEnds 2 weeks later when the zygote is implanted in the wall of the uterus

Period of the Zygote

Period of the EmbryoFrom 3 to 8 weeks after conceptionBody parts are formed during this period

Embryo rests in the amnion filled with amniotic fluid

Umbilical cord joins embryo to placenta

Prenatal Structures

Period of the FetusFrom 9 weeks after conception to birth

Increase in size and systems begin to function

Age of viability: 22 to 28 weeks

First MonthBy the end of the

first month, the embryo is about 1/10 of an inch long. The heart, which is no larger than a poppy seed, has begun beating.

First Month

Two MonthsThe embryo is about

1 inch long and has distinct, slightly webbed fingers. Veins are clearly visible. The heart has divided into right and left chambers.

Two Months

Three MonthsBy now the fetus is 2 1/2

to 3 inches long and is fully formed. He has begun swallowing and kicking. All organs and muscles have formed and are beginning to function.

Four MonthsYour baby is

covered with a layer of thick, downy hair called lanugo. His heartbeat can be heard clearly. This is when you may feel your baby's first kick.

4 months

Five Months A protective coating

called vernix caseosa begins to form on baby's skin. By the end of this month, your baby will be nearly 8 inches long and weigh almost a pound.

Six MonthsEyebrows and

eyelids are visible. Your baby's lungs are filled with amniotic fluid, and he has started breathing motions. If you talk or sing, he can hear you.

6 Months

Seven MonthsBy the end of the

seventh month, your baby weighs about 3 1/2 pounds and is about 12 inches long. His body is well-formed. Fingernails cover his fingertips

Eight MonthsYour baby is gaining

about half a pound per week, and layers of fat are piling on. He has probably turned head-down in preparation for birth. He weighs between 4 and 6 pounds.

Nine MonthsYour baby is a hefty

6 to 9 pounds and measures between 19 and 22 inches. As he becomes more crowded, you may feel him move around less.

The birth episodeBirth

After about thirty-eight weeks in the womb, the baby is considered "full term," or ready for birth. Fetal presentation refers to the body part closest to the mother's cervix. There are three types of presentation: Cephalic (normal), breech, and transverse.

Labor and DeliveryStage 1: starts when the muscles of the uterus contract and ends when the cervix is fully enlarged (about 10 cm)

Stage 2: baby is pushed down the birth canal

Stage 3: placenta is expelled

Stages of labor1. During the last weeks of pregnancy, it is common for the mother to experience false labor, or Braxton-Hicks contractions.

2. The first stage of labor usually begins with relatively mild contractions, leading to stronger contractions and the dilation of the cervix to accommodate the baby's head (10 centimeters).

3. Toward the end of the first stage, which may take from eight to twenty-four hours, a period of transition begins, and the baby's head begins to move through the birth canal.4. The second stage of labor is from complete dilation of the cervix to birth, lasting about one to one and one-half hours.5. During the third stage of labor, which lasts only a few minutes, the afterbirth (consisting of the placenta and umbilical cord) is expelled

Three Stages of Labor

Birth Complications• Lack of oxygen (anoxia): Often leads to surgical removal of the fetus (C-section)

• Premature and Small-for-date infants

• Prematurity is less serious than small-for-date

Low-birth weight infantsNormal is around 7.5

poundsLow-birth weight is

5.5 pounds or less6 or 7 percent of all

births in U.S.At risk for

developmental, neurological, and health problems

Pre-term BabiesFormerly called

prematureMore than three

weeks before due date

At risk for respiratory distress syndrome (RDS)

Extended oxygen use=Retinopathy of Prematurity

Problems during labor and delivery (1 of 3)1. Faulty power is the failure of the

uterus to contract strongly enough to make labor progress to an actual delivery. Induced labor can be stimulated by the hormone oxytocin.

2. A faulty passageway condition occurs when the placenta develops so close to the cervix that it blocks the baby's passage down the birth canal during labor. This condition is called placenta previa.

3. A faulty passenger condition occurs when problems exist with the baby's position or size. Usually babies enter the birth canal head first, but occasionally one turns in the wrong direction during contractions. Forceps sometimes are used to remedy the situation.4. In a Caesarean section, the mother receives a general anesthetic and the baby is removed surgically. Techniques for this surgery have improved; however, a common criticism is that too many Caesareans are performed.

To deal with such problems, in most hospitals, electronic fetal monitoring is used to record uterine contractions and the fetal heart rate.

Prenatal influences on the childA. Key concepts1. Canalization is seen in

prenatal development.2. Drugs and other harmful

environmental influences can also canalize development, usually in negative ways.

3. Risk factors can interfere with canalized processes that lead to the development of specific organs.

Prenatal health care (1 of 2)1. Adequate early prenatal

health care is critical to infant and maternal health.

2. There are racial differences in adequacy of care.

3. Special programs have been implemented in communities to help high-risk mothers.

Stress

1. Prolonged anxiety just before or during pregnancy increases the likelihood of medical complications.2. Emotional stress is related to spontaneous abortion as well as to labor and birthing problems.

General Risk FactorsNutrition: adequate amount of food, protein, vitamins, & minerals

Stress: decreases oxygen to fetus and weakens mother’s immune system

Mother’s Age: neither too young, nor too old

Home FactorsTeenage Pregnancy“Babies having babie

s”--own growth is not complete

Pelvic cradle not ready

Threat to educationResponsibility not yet

learnedMaternal malnutrition

Domestic ViolenceSeven to Eight

percent of pregnant women are beaten by partners; most more than once

High rate of miscarriage

Prenatal Diagnosis and Treatment

Diagnosis: ultrasound, amniocentesis, and chorionic villus sampling can detect physical deformities and genetic disorders

Treatment: fetal medicine and genetic engineering are experimental

Prenatal Diagnosis

Amniocentesis Chorionic Villus Sampling

Maternal diet and nutrition1. Poor nutrition leads to specific

physical deformities and increased risk for prematurity and infant mortality; later nutritional deprivation leads to a reduced number of brain cells.

2. Pregnant women should eat between two hundred and one thousand calories more per day, adding mainly carbohydrates and protein.

Influences on Prenatal DevelopmentGeneral Risk FactorsTeratogens: Diseases, Drugs, and Environmental Hazards

How Teratogens Influence Prenatal Development

Prenatal Diagnosis and Treatment

Maternal Diseases (1 of 2)Rubella, or German measles. Disastrous in

first trimester.Syphilis and gonorrhea. Blindness, jaundice,

anemia, pneumonia, skin rash, early death. Silver nitrate in the eyes.

Genital herpes. (1) Disease of skin and mucous membranes, or (2) blindness, permanent brain damage, seizures, and developmental delay.

Maternal diseases (2 of 2)Cytomegalovirus (CMV). High risk for

infants; jaundice, microcephaly, deafness, and eye problems.

Toxoplasmosis. Parasite from uncooked meat and cat feces. Low birth weight, enlarged liver and spleen, microcephaly, anemia, and calcifications in the brain.

Pediatric AIDS.

Negative Prenatal Influences on the Child

Window of opportunity concept--critical time of vulnerability

Teratogen is any substance or influence that can interfere with or damage a child’s growth

Teratogens: Diseases, Drugs, and Environmental Hazards

• Many diseases pass through the placenta directly and attack the fetus

• Potentially dangerous drugs not limited to cocaine but include alcohol and caffeine

• Environmental hazards are treacherous because we’re often unaware of their presence

How Teratogens Influence Prenatal Development

Not universally harmfulHarm particular structures at a particular point in development in particular animals

Teratogenic Medicinal drugsThalidomide is a sedative, also an anti-

nausea drug--but deforms children.Diethylstilbestrol (DES) was used to

prevent miscarriages but causes damage to reproductive systems of offspring.

Other potentially harmful prescribed drugs are accutane, streptomycin, and tetra-cycline.

Teratogenic non-medicinal drugs (1 of 3)

MarijuanaActive ingredient is

tetrahydra-conabaninol or THC

Is stored in fatty tissues of body

Placenta is no barrierBabies are born with

psych. if not physical addiction

Effects of Teratogens

HeroinAn opiate not totally

unlike morphine, but more addictive

Severe withdrawal symptoms

Newborn babies of heroin addicts vomit, tremble, cry, and have fever, disturbed sleep, and abnormal cries

Fetal alcohol syndrome

CNS damage, heart defects, small head, distortion of joints, and abnormal facial features

Are evident in their inability to pay attention or maintain attention

TobaccoNicotine and carbon

monoxide interfere with fetal oxygen supply

Smoking is associated with low birth weight, spontaneous abortion, higher infant mortality, and poor postnatal adjustment