from conception to birth period of the zygote period of the embryo period of the fetus
TRANSCRIPT
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