Chapter 3 - Prenatal Development Flashcards Preview

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Flashcards in Chapter 3 - Prenatal Development Deck (106):
1

Prenatal Development

Prenatal development begins with conception The ovum is 1/175 inch, the largest cell in the human body Sperm cells are much smaller, 1/500 inch

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Advantages and Disadvantages of parenthood mentioned by American Couples

Advantages • Giving and receiving affection • Experiencing the stimulation and fun that children add • Being accepted as a responsible and mature member of the community • Experiencing new growth and learning opportunities • Having someone to carry on to after ones death • Gaining a sense of accomplishment and creativity from helping children grow • Having someone to provide care in old age • Learning to be less selfish and to sacrifice • Help with work or add to income to family resources Disadvantages • Loss of freedom • Financial strain • Family work conflict • Interference with moms employment or career progress • Worries over children’s health, safety, wellbeing • Risks of the world • Reduced time with partner • Loss of privacy • Fear of children turning out badly, through no fault of their own

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Ovulation and Menstruation

About once every 28 days, an ovum is released from one of the ovaries, and begins to travel down a fallopian tube The corpus luteum secretes hormones that will prepare the uterine lining for implantation If pregnancy doesn’t occur, the corpus luteum shrinks, and the uterine lining is discarded

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Sperm

On average, males produce about 300 million sperm per day During intercourse, sperm cells are released, and swim through the cervix and into the fallopian tube Only 300 to 500 sperm cells will reach the ovum, if one is present at the time of intercourse Or soon afterwards; sperm cells live for about 6 days Usually, fertilization occurs either the day of ovulation or in the 2 days afterwards

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Prenatal development three phases

The period of the zygote The period of the embryo The period of the fetus

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The Period of the Zygote

Lasts from conception until implantation is complete, approximately 2 weeks The zygote duplicates while travelling down the fallopian tube The first duplication takes about 30 hours, after which cell duplication speeds up considerably A yolk sac forms; this will produce blood cells until the liver, spleen, and bone marrow are mature enough to produce their own Note that perhaps as many as 30% of zygotes do not survive these first 2 weeks

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Blastocyst

the zygote 4 days after fertilization, when the tiny mass of cells forms a hollow, fluid-filled ball

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Embryonic disk

a small cluster of cells on the inside of the blastocyst, from which the new organism will develop

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Trophoblast

the thin outer ring of cells of the blastocyst, which will become the structures that provide protective covering and nourishment to the new organism

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Implantation

attachment of the blastocyst to the uterine lining, which occurs 7 to 9 days after fertilization The trophoblast multiplies quickly after implantation begins, forming the amnion and chorion

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Amnion

the inner membrane that encloses the prenatal organism develops from the Trophoblast

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Amniotic fluid

the fluid that fills the amnion, helping to keep temperature constant and to provide a cushion against jolts caused by the mother’s movement

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Chorion

develops from the Trophoblast it is the outer membrane that surrounds the amnion and sends out tiny, fingerlike villi, from which the placenta begins to develop These are the villi that are sampled in chorionic villus sampling

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Placenta

the organ that permits exchange of nutrients and waste products between the bloodstreams of the mother and the embryo, while also preventing the mother’s and embryo’s blood from mixing directly

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Umbilical cord

Umbilical cord - the long cord that connects the prenatal organism to the placenta, delivering nutrients and removing waste products This cord grows to a length of 1-3 feet One large vein delivers nutrient-rich blood to Baby Two arteries remove Baby’s waste products The constant flow of blood keeps the cord firm, so it rarely tangles with Baby’s movements

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The Period of the Embryo

Embryo - the developing organism from the third week, when implantation is complete, through the eighth week after conception Initially only about the size of an apple seed, but all major internal and external structures form during this period

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The Period of the Embryo Week 3

Week 3, the inner cell mass differentiates into three layers 1. Endodermal: internal organs and glands 2. Ectodermal: the parts of the body that maintain contact with the outside world—the nervous system; the sensory parts of the eyes, nose, and ears; skin; hair 3. Mesodermal: muscles, cartilage, bone, sex organs, and heart The ectoderm folds over to form the neural tube. At 3 ½ weeks the brain starts to develop from the neural tube

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The Period of the Embryo week 4

Beginning of week 4, the embryo looks like a tiny tube By the end of week 4, it assumes a curved form, with a bump below the head (a primitive heart) and tiny buds that will become the limbs

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The Period of the Embryo 5th week

In the 5th week, the head and brain develop rapidly The upper limbs form The lower limbs appear and look like small paddles

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The Period of the Embryo 6th week

In the 6th week, the head continues to grow rapidly Differentiation of the limbs occurs as elbows, fingers, and wrists become recognizable The ears and eyes are discernable

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The Period of the Embryo week 7

the limbs develop rapidly Stumps appear that will form fingers and toes

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The Period of the Embryo week 8,

By the end of week 8, the embryo has distinctly human features Almost half of the embryo consists of the head The eyes, ears, toes, and fingers are easily distinguishable All internal and external structures have formed

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The Period of the Fetus

Fetus - the developing organism from the 9th week to the 38th week after conception During this period, we see mostly Further development of the already formed organ structures Increases in size and weight At the beginning of this period, the fetus weighs less than an ounce and measures about 5 cm in length By birth, about 266 days after conception, most weight 3 to 3.5 kg and measure about 51 cm in length Fetal growth begins to slow around the eighth month Appearance changes drastically during the fetal period The head grows less than the other parts of the body The head’s ratio decreases from 50% of the body mass at 12 weeks to 25% at birth By 6 to 7 months of age, the fetus has a chance of survival outside of Mom’s body This process isn’t complete until 9 months

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First trimester 9 weeks to 3 months

The organs, muscles and nervous system start to become organized and developed Facial features become more human looking as the eyes move from the sides of the head to the front Fetal activity begins in the 3rd month, when the fetus is capable of forming a fist and wiggling toes Mom can’t feel this yet The fetus appears to become sensitive to environmental stimulation by this point—it moves its whole body in response to a touch stimulus The skin is transparent until the 3rd month, when it begins to thicken By 3 months, the brain is organized into functional subdivisions—seeing, hearing, thinking, etc Sexual development becomes apparent by the end of the 3rd month The eyelids seal shut near the beginning of the 3rd month, and stay that way for 3 months

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Second trimester 4 months

By the 4th month, the eyes are sensitive to light through the lids Finger and toe nails appear by the 4th month, as do pads that will have the fingerprints Head hair begins to grow

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Second trimester 5 months

By the 5th month, a loud noise may activate the fetus During this month, the fetus swims effortlessly The fetus is now capable of kicking and turning It may also begin to display rhythms of sleep and activity By about 17-20 weeks, the fetus has developed vernix and lanugo

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Second trimester 6 months

By 6 months, a bone structure begins to support a more erect posture

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third trimester 7 months

By the 7th month, brain connections are sufficient for the fetus to exhibit a sucking reflex when the lips are touched A baby born after only 7 months will need to be provided with extra oxygen, will have to take food in very small amounts, and will have to live for several weeks in an incubator for temperature control

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third trimester 8 months

In the 8th month, fat appears under the skin to help regulate body temperature A baby born at 8 months is susceptible to infection Beginning in the 8th month, Mom’s body contributes disease-fighting antibodies to the fetus, developed through her own exposure to foreign bodies

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vernix and lanugo

Vernix – white cheese like substance that protects the skin from chapping in the amniotic fluid Lanugo – also appears around the body helping the vernix

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Age of viability

the age at which the infant has a chance to survive if born prematurely Currently, the age of viability is about 23 to 24 weeks

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Premature birth

The major obstacle for a premature baby is the immaturity of the air sacs of the lungs A baby born very prematurely will also not be able to digest food Fat will not yet have formed under the skin to assist in temperature regulation

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fetal differences

Some precursors of later individual differences become evident shortly before birth For instance, fetuses that are more active in the womb tend to be more active and less fearful at 2 years of age These fetal differences aren’t consist enough to reliably predict later differences, though

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Teratogen

any environmental agent that causes damage during the prenatal period The impact of a teratogen is influenced by • Dose • Timing/ age (The embryonic period is when damage is most likely to occur. During the fetal period it is usually minor) • Heredity • Other negative influences (nutrition, presence of other teratogens)

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Thalidomide

was widely marketed to pregnant women in the 1960s Depending on timing of exposure, babies were born with malformation s of the eyes and ears, deformations of the internal organs, or fused fingers and toes, or (most famously) phocomelia

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Diethylstilbestrol (DES)

Prenatal medication meant to prevent miscarriage. 1945-1970 Synthetic hormone Daughters of mothers who used this showed abnormally high rates of cancer of the vagina, infertility, malformation of the uterus, miscarriages and premature birth once they reached adolescence and young adulthood. Sons showed increased rate of genital abnormallies and cancer of the testes

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Aspirin use during pregnancy

Possibly causes • Low birth weight • Infant death • Poor motor development • Lower intelligent scores in early childhood

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Caffeine use during pregnancy

More then 100mg a day Low birth weight Miscarriage chances increase

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Antidepressant use during pregnancy

Premature delivery Birth complications including –respiratory distress – persistent high blood pressure in infancy

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Illegal drugs during pregnancy

At risk for - Prematurity - Low birth weight - Physical defects - Breathing dificultys - Death soon after birth If born addicted - Feverish - Irritable - Trouble sleeping - Shrill cries - Less attentive to their environment - Slow motor development - Can normalize after infancy

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Tobacco use during pregnancy

It constricts blood vessels in the mother that lessons blood flow to the uterus and causes abnormal placenta growth. This reduces nutrient availability to the fetus. Quitting at any time during pregnancy helps. - Low birth weight (best known affect) - Miscarriage - Premature birth - Impaired heart rate and breathing during sleep - Infant death - Asthma - Cancer - Behavioral abnormallies - ADHD symptoms “passive smokers” – lots of second hand smoke

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Effects of Alcohol on prenatal development

In Canada and the US, this is the most widely used drug that is known to harm the fetus Almost 15% of Canadian mothers report consuming some amount of alcohol during the pregnancy Prenatal alcohol exposure is the leading cause of developmental disability among children in Canada and in the rest of the Western world The withdrawal effects in newborns of mothers who drink heavily are similar to those in newborns whose mothers are drug addicted

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Fetal Alcohol Spectrum Disorder (FASD)

a range of physical, mental, and behavioural outcomes caused by prenatal alcohol exposure This is divided into three categories 1. Fetal Alcohol Syndrome (FAS) 2. Partial Fetal Alcohol Syndrome (P-FAS) 3. Alcohol-Related Neurodevelopmental Disorder (ARND)

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Fetal Alcohol Syndrome (FAS)

the most severe form for FASD, distinguished by slow physical growth, facial abnormalities, and brain injury; usually seen in children whose mothers consumed large amounts of alcohol during most or all of pregnancy Diagnosed when there is a) slow physical growth b) a pattern of three facial abnormalities: short eyelid openings, thin upper lip, a smooth or flattened philtrum, c) brain injury, evident in a small head and impairment in at least three areas of functioning, such as memory, language, attention span, activity level, planning, motor coordination, social skills Defects of the eyes, ears, nose, throat, heart, genitals, urinary tract, or immune system may also be present

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Partial Fetal Alcohol Syndrome (P-FAS)

a form of FASD characterized by facial abnormalities and brain injury, but less severe than FAS; usually seen in children whose mothers drank alcohol in smaller quantities during pregnancy Diagnosed when we see a) two of the three facial abnormalities and b) brain injury, evident in at least three areas of impairment

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Alcohol-Related Neurodevelopmental Disorder (ARND)

the least severe form of FASD, involving brain injury, but with typical physical growth and absence of facial abnormalities

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How does Fetal Alcohol Spectrum Disorder (FASD) occur?

Alcohol interferes with cell duplication and migration in the neural tube We see arrested brain growth, structural damage, and abnormalities in the electrical and chemical activity of the brain Also, it takes a lot of oxygen to metabolize alcohol, leaving less oxygen for the developing Baby Note that even one drink per day is associated with reduced head size and body growth, even into adolescence

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Radiation

- Miscarriage with underdeveloped brains - Physical deformities - Slow physical growth - Increased chance of cancer - Abnormal brain wave activity - Low intelligence test scores - Language disorders - Emotional disorders

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Environmental pollution

Babies are born with pollutants in their system already. Possible effects Impair prenatal development Increases chances of life threatening diseases Mercury – impared speech, mental retardation, physical deformitys, difficulty chewing and swallowing, uncoordinated movment. Avoid long lived fish during pregnancy because of risk of mercury Polychlorinated Biphenyls (PBC’s) – used to insulate electrical equipment. Causes: low birth weight, discoloured skin, deformities in the gums and nails, brain wave abnormallys, delayed cognitive development Lead – premature birth, low birth weight, brain damage, physical defects, lower mental and motor development Dioxins – toxins resulting from incineration – linked to brain, immune system, and thyroid damage, breast and uterine cancer, sex ratio of births (2 time as many girls from an effected father)

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Rubella

This virus can damage the central nervous system of the fetus, resulting in blindness, deafness, and developmental disability The heart, liver, and bone structure may also be damaged, depending on the timing of infection Affects only 2-3% of offspring of mothers infected within 2 weeks after their last period, 50% of offspring when the infection is in the first month following conception, 22% when it occurs during the second month, 6-8% when it’s during the 3rd, and very low incidence thereafter

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HIV

This virus is transmitted through body fluids, and can be transmitted from mother to fetus through the placenta, from mother to baby during the birth process, or from mother to baby through breast milk HIV can act as a teratogen Some infected babies are born with facial deformities Larger-than-normal eye separation Boxlike foreheads Flattened nose bridges Misshapen eye openings Babies who get AIDs and are untreated have a 50% chance of dying by 1 and 90% chance of dying by 3.

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Herpes

Types Cytomegalovirus –most frequent prenatal infection, transmission through repertory or sexual contact often with out symptoms. Herpes simplex 2 – sexually transmitted, especially dangerous,

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Toxoplasmosis

a parasitic disease caused by eating raw or undercooked meat or through contact with the feces of infected cats; during the first trimester, it leads to eye and brain damage In the second and third trimesters, it’s linked to mild visual and cognitive impairments About 80% of affected newborns with no obvious signs do develop disabilities later in life In an adult, the symptoms resemble a cold, so a person can contract toxoplasmosis and never realize it

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Exercise

In healthy, physically fit women, regular moderate exercise is related to increased birth weight So walking, swimming, biking, aerobic workouts = good Very frequent, vigorous, extended exercise results in lower birth weight than in healthy controls So working up a sweat for more than 30 minutes, 4 or 5 days a week, especially in the third trimester = bad During the third trimester, mothers may have to cut back on exercise Note, however, that most women don’t engage in enough moderate exercise during pregnancy to promote their own and their baby’s health Keeping fit reduced physical discomforts, like back pain and upward pressure on the chest Pregnant women with health problems should consult with doctors about fitness routines

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Nutrition

Consider the increase in both size and number of cells during prenatal development The quality of Mom’s diet, during and before pregnancy, is paramount for Baby’s nutrition Mother should gradually increase calories during pregnancy. 10 extra calories a day in first trimester, 265 in second, 430 in third. Resulting in a weight gain of 25 – 30 pounds. Maternal malnutrition is often confounded with inadequate housing and health care, inferior education and sanitation, and the daily stress of poverty This makes it difficult to isolate the effects of malnutrition from other factors Using a prenatal multivitamin supplement can provide protection against a number of birth defects

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Prenatal Malnutrition

Malnutrition can occur even when there is enough food consumption, if it’s not the right kinds of foods First trimester of malnutrition in the most likely to result in miscarriage or physical deformities. Third trimester malnutrition results in lower brain weight because the brain is developing during this time. Can cause serious damage to the central nervous system of the baby. Protein deficits can produce damage to the kidneys and intestines, and disrupt skeletal growth in the fetus Suppresses development of the immune system and can make the infant more susceptible to respiratory illness. Infants can be irritable and unresponsive to stimulation and have a high pitched cry. Low intake of certain vitamins can affect the eyes and internal organs and increase the number of malformations The intellectual abilities of babies who suffered prenatal malnutrition depend in large part on their childhood environments

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Infant Malnutrition

Babies who are malnourished both prenatally and postnatally are more likely to show delayed motor and social development They become relatively inattentive, unresponsive, and apathetic Poverty-stricken babies whose diets are supplemented are more advanced in motor development and more socially interactive and energetic Children who were malnourished prenatally but have adequate diet and stimulation in infancy and childhood tend to show no long-term intellectual deficit An enriched home environment may compensate for many of the effects of malnutrition The outcome also depends on the timing and severity of the malnutrition, though

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Effects of maternal malnutrition can include

• Brain weight up to 1/3 less than expected • Deficits of between 6 and 25% in the size of major internal organs • Increased rates of spontaneous abortion and infant death • Increased rates of congenital defects • Low birth weight • Prematurity • Increased rates of schizophrenia later in life

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Stress

Miscarriage, premature birth, low birth weight Digestive illnesses colic Newborn irritability Feeding and sleep problems during infancy Behavioural problems at age 4 Heightened probability of congenital physical anomalies, such as heart defects and cleft palate

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There are confounds in the research between maternal anxiety during pregnancy and some later child outcomes

Confounds - Reports of stress are usually collected postnatally - Can’t separate prenatal from postnatal influences - Mom and baby are also genetically related It’s unlikely that the confounds could account for all of the effects we see in babies whose mothers experience significant prenatal stress - Some effects of maternal stress are evident during the prenatal period—low birth weight and problems during delivery couldn’t be due to the postnatal environment - Children born to mothers who were pregnant during large-scale disasters often show poorer intellectual and language abilities in childhood

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When is stress not predictive of negative outcomes

When stress is within normal limits, it’s not predictive of negative outcomes Particularly if Mom is well-nourished, financially stable, and carrying wanted pregnancies Social support is important here as well, and makes negative outcomes much less likely

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Blood Incompatibility

Rh factor incompatibility can occur if Mom is Rh-negative and Dad is Rh-positive If any of Baby’s Rh-positive blood crosses the placenta, Mom begins to build antibodies Since antibodies take time to form, the first child is rarely affected There is a vaccine, as long as you know to take it

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Parental Age

The optimal time for childbearing has traditionally been considered to be between the ages of 20 and 34, with 25-29 as the best time within this range Births to mothers over 35 or under 20 are sometimes considered a cause for concern

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Achondroplasia

Achondroplasia is an age-related mutation in the father’s sperm that becomes dominant in the child who inherits it Dad’s age is important contributor because of mutation in the father’s sperm. The most obvious characteristics are dwarfism and a large head, with a prominent forehead and a depressed bridge of the nose

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Increased maternal age

Increased maternal age is associated with an increased likelihood of giving birth to a baby with Down syndrome The relative frequency of mutation in the father’s sperm increases with age as well Dad’s age may also be an important contributor to autistic disorder Some studies say older Moms are at risk for preterm birth, difficulties during delivery, and both infant and maternal mortality More the case 2 or 3 decades ago than now Older Moms are more educated now, and thus more likely to seek early prenatal care and to be in good health When Mom’s health is good, being older seems to carry only minimal risk

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teen Moms

Babies of teen Moms are at greater than average risk Increased risk of complications during pregnancy, preterm birth, and low birth weight This may be largely because of Inadequate prenatal care More risky health behaviours Stress

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Nurse-Family Partnership

A voluntary home visit program for first time, low income, expectant mothers. Visits happened 7 times during pregnancy, once a month for the first two years after birth Goals: reduce birth complications, promote competent parenting, improve family conditions Results: higher language and intelligence scores, better academic achievement, less behavior problems, fewer subsequent births, more contact with the father, less welfare dependence, less parental stress,

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Preeclampsia (toxemia)

Blood pressure increases sharply in the face, hands, and feet in the second half of pregnancy. If untreated it can cause convulsions in the mother and fetal death.

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Why mothers might not seek prenatal care

Situational barriers – difficulty finding a doc, transportation, ext. Personal barriers – stress, lack of knowledge, family demands

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Prenatal Iron deficiency and memory in infants

- Diabetes buts the baby at risk for birth defects during early pregnancy and unusually large babies in late pregnancy - In this case the baby needs a lot iron. They will use their bodies own stores. This can cause a decline in brain activity and damage the development of the hippocampus. - They can score lower in intelligence in childhood - This is due to memory impairment

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Dos of healthy pregnancy

- Make sure you have been vaccinated before pregnancy - See a doctor as soon as you suspect pregnancy and go for regular appointments throughout pregnancy - Eat well balanced meals, take supplements before and during pregnancy, and eat the appropriate amount of calories - Obtain literature from your doctor, library, bookstore - Keep physically fit - Avoid emotional stress - Get plenty of rest - Enrol in prenatal and childbirth class with your partner

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Don’ts of health pregnancy

- Don’t take drugs (even legal ones) without talking to your doc - Don’t smoke or expose yourself to second hand smoke - Don’t drink alcohol - Don’t engage in activities that would expose you to chemicals or radiation - Don’t expose your baby to harmful infectious diseases - Don’t go on a diet - Don’t gain too much weight

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What percentage of U.S. married couples bear children today?

70 percent

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Currently, the average number of children per couple in the United States and Canada is

1.8

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During the period of the zygote, the cluster of cells on the inside of the blastocyst form the

embryonic disk, which becomes the new organism.

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After tiny blood vessels emerge and burrow into the uterine wall,

the developing placenta permits food and oxygen to reach the developing organism and waste products to be carried away.

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During the final trimester, the fetus's brain continues to grow, although

the head does not become too large to pass through the birth canal.

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The connection between low birth weight and cardiovascular disease was found to be strongest for

people whose weight-to-length ratio at birth was very low.

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Commonly used as a sedative during the early 1960s, thalidomide caused

gross deformities of the embryo's developing arms and legs.

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Babies who are prenatally exposed to cocaine, heroin, or methadone are at risk for

low birth weight, physical defects, breathing difficulties, and death around the time of birth.

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What percentage of U.S. women smoke during pregnancy

14 percent

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The most severe form of fetal alcohol spectrum disorder (FASD), usually seen in children whose mothers consumed large amounts of alcohol during most or all of pregnancy, is distinguished by

slow physical growth, facial abnormalities, and brain injury.

83

Low-level radiation exposure, such as from medical X-rays, can

increase the risk of childhood cancer.

84

High levels of prenatal mercury exposure can cause

widespread brain damage.

85

Abnormalities resulting from prenatal rubella increase

the risk of severe mental illness

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Keri just discovered that she's pregnant and asks you what vitamins she should start taking. Which of the following vitamin-mineral supplements helps to prevent abnormalities of the neural tube, including anencephaly and spinal bifida?

folic acid

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Toxemia, also known as preeclampsia, is a complication during pregnancy that can cause the woman to experience

a sharp increase in blood pressure and swelling of the face, hands, and feet.

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As a result of ________ in critical brain areas, a diabetic pregnancy places the fetus at risk for long-term academic difficulties

iron depletion

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Group prenatal care is an effective intervention for

minority expectant mothers.

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For most expectant parents, the prenatal period is a period of

major life change accompanied by excitement.

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The most important element in preparing for parenthood is a

close relationship between the expectant parents.

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First Trimester The period of the embryo 3-8 weeks

Week 3, the inner cell mass differentiates into three layers The ectoderm folds over to form the neural tube. At 3 ½ weeks the brain starts to develop from the neural tube Beginning of week 4, the embryo looks like a tiny tube By the end of week 4, it assumes a curved form, with a bump below the head (a primitive heart) and tiny buds that will become the limbs In the 5th week, the head and brain develop rapidly The upper limbs form The lower limbs appear and look like small paddles In the 6th week, the head continues to grow rapidly Differentiation of the limbs occurs as elbows, fingers, and wrists become recognizable The ears and eyes are discernable the limbs develop rapidly Stumps appear that will form fingers and toes By the end of week 8, the embryo has distinctly human features Almost half of the embryo consists of the head The eyes, ears, toes, and fingers are easily distinguishable All internal and external structures have formed

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First Trimester The period of the fetus first trimester 9 weeks to 3 months

The organs, muscles and nervous system start to become organized and developed Facial features become more human looking as the eyes move from the sides of the head to the front Fetal activity begins in the 3rd month, when the fetus is capable of forming a fist and wiggling toes Mom can’t feel this yet The fetus appears to become sensitive to environmental stimulation by this point—it moves its whole body in response to a touch stimulus The skin is transparent until the 3rd month, when it begins to thicken By 3 months, the brain is organized into functional subdivisions—seeing, hearing, thinking, etc Sexual development becomes apparent by the end of the 3rd month The eyelids seal shut near the beginning of the 3rd month, and stay that way for 3 months

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First Trimester 3 Peirods

Conception – 3 months The period of the zygote 2 weeks The period of the embryo 3-8 weeks The period of the fetus first trimester 9 weeks to 3 months

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Second Trimester

3-6 months – period of the fetus By the 4th month, the eyes are sensitive to light through the lids Finger and toe nails appear by the 4th month, as do pads that will have the fingerprints Head hair begins to grow By the 5th month, a loud noise may activate the fetus During this month, the fetus swims effortlessly The fetus is now capable of kicking and turning It may also begin to display rhythms of sleep and activity By about 17-20 weeks, the fetus has developed vernix and lanugo By 6 months, a bone structure begins to support a more erect posture Further development of the already formed organ structures Increases in size and weight Appearance changes drastically during the fetal period The head grows less than the other parts of the body

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Third Trimester

6-9 month – Period of the fetus By the 7th month, brain connections are sufficient for the fetus to exhibit a sucking reflex when the lips are touched A baby born after only 7 months will need to be provided with extra oxygen, will have to take food in very small amounts, and will have to live for several weeks in an incubator for temperature control In the 8th month, fat appears under the skin to help regulate body temperature A baby born at 8 months is susceptible to infection Beginning in the 8th month, Mom’s body contributes disease-fighting antibodies to the fetus, developed through her own exposure to foreign bodies By 6 to 7 months of age, the fetus has a chance of survival outside of Mom’s body By birth, about 266 days after conception, most weight 3 to 3.5 kg and measure about 51 cm in length Fetal growth begins to slow around the eighth month This process isn’t complete until 9 months

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Effects of Some Infectious Diseases During Pregnancy TABLE 1

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Female Reproductive Organs and Fertilization DIAGRAM

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First Trimester DIAGRAM

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Second and Third DIAGRAM

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Prenatal diagnosis Methods TABLE

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Sensitive Periods in Prenatal Development DIAGRAM

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Sex Cell Creation DIAGRAM

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Uterus and Placenta DIAGRAM

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Fetal Alcohol Spectrum Disorder Criteria TABLE

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Congenital 

Means present from birth