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Chapter 4

Chapter 4.docx

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Gustavo Gottret

-know apgar scale and point system based on given situation; calculate the apgar score based on situation Chapter 4 Prenatal Development -is divided into 3 periods 1) The Germinal Period -the period of prenatal development that takes place in the first 2 weeks after conception -includes the creation of the zygote, continued cell division, and the attachment of the zygote to the uterine wall -1 week after conception, the zygote is composed of 100-150 cells -differentiation occurs as inner and outer layers of the organism are formed -the blastocyst is the inner mass of cells that develops during the germinal period -the trophoblast is the outer layer of cells that develops during the germinal period -the trophoblast provides nutrition and support for the embryo -implantation (attachment of the zygote to the uterine wall) occurs 11-15 days after conception 2) Embryonic Period -the period of prenatal development that occurs from 2-8 weeks after conception -the rate of cell differentiation intensifies, support systems for the cells form, and organs appear -once the zygote attaches to the uterine wall, its cells form 2 layers, and the mass of cells is now called an embryo instead of a zygote -the endoderm (inner mass of cells) will develop into the digestive and respiratory system -the outer layer is divided into 2 parts -the ectoderm is the outermost layer which will become the nervous system, sensory receptors (sensory organs) and skin parts (hair, nails, etc.) -the mesoderm is the middle layer which will become the circulatory system, bones, muscles, excretory system, and the reproductive system -life support systems for the embryo include: -the amnion is like a bag or envelope that contains a clear fluid in which the developing embryo floats; amniotic fluid provides an environment that is temperature and humidity controlled, as well as shock proof -the placenta consists of a disc-shaped group of tissues in which small blood vessels from the mother and the offspring intertwine but do not join -the umbilical cord contains 2 arteries and 1 vein and connects the fetus to the placenta -very small molecules like oxygen, water, salt, food from the mother's blood, carbon dioxide, and digestive wastes from the embryo pass back and forth between mother and fetus -large molecules cannot pass through the placenta wall (i.e.: RBCs, harmful substances like bacteria, maternal wastes, hormones, etc.) -at 16 weeks into development, the kidneys start producing urine; fetal urine is the main source of the amniotic fluid -organogenesis is the process of organ formation that takes place during the first 2 months of prenatal development 3) Fetal Period -the prenatal period of development that begins 2 months after conception and lasts for 7 months -growth and development continue and is actively moving its arms and legs, opening and closing its mouth, moving its head, etc. -facial features and limbs become more distinguishable -at this time, a growth spurt occurs in the body's lower parts -prenatal reflexes are stronger -arm and leg movements can be felt for the first time by the mother -the fetus has a chance of surviving outside the womb (is viable) by the 6th to 7th month of pregnancy -infants born in this time frame need help breathing because their lungs aren't mature -during the last 2 months, the baby weighs on average 3.2 kg and is 50.8 cm long -as well, fatty tissues develop and organ systems step up -the 3 periods of prenatal development are not equivalent to the 3 trimesters The Brain -by the time babies are born, they have 100 billion neurons -during prenatal development, neurons spend time moving to the right locations and start to become connected (especially during the first 2 trimesters) -the 3rd trimester and the first 2 years of postnatal life are characterized by connectivity and functioning of neurons -a neural tube is formed as part of the nervous system during the 18th to 24th day after conception -if the neural tube fails to close, this may result in anencephaly and spina bifida -anencephaly occurs when the head end of the neural tube fails to close and they die in the womb or shortly after birth -neural tube defects may be prevented by taking adequate amounts of B vitamin foli acid -once the neural tube is closed, neurogenesis occurs throughout prenatal development -it is estimated that at its peak, 200 000 neurons are generated every minute -neuronal migration involves cells moving outward from their point of origin to their appropriate locations and creating the different levels, structures, and regions of the brain Teratology and Hazards to Prenatal Development -a mother's womb can provide a protective environment or affect the fetus adversely -a teratogen is any agent that can potentially cause a birth defect or negatively alter cognitive and behavioural outcomes -e.g.: drugs, incompatible blood types, infectious diseases, nutritional deficiencies, maternal stress, advanced maternal and paternal age, and environmental pollutants -every fetus is exposed to teratogens to some degree; the dose, genetic susceptibility, and the time of exposure influence the type and severity of the effects 1) Dose -the greater the dose of an agent (like drugs), the greater the effect 2) Genetic Susceptibility -the effects of teratogens are linked to the genotype of the pregnant women and the genotype of the embryo or fetus -i.e.: how a mother metabolizes a drug influences the degree to which its effects are transmitted -differences in placental membranes and placental transport affect exposure 3) Time of Exposure -the embryonic period is more vulnerable than the fetal period since organs are still being formed -each body structure has its own critical period of formation -after organogenesis, teratogens are less likely to cause defects -exposure during the fetal period is more likely to stunt growth or to create problems with the way organs function Prescription and Non-Prescription Drugs -prescription drugs that can function as teratogens include antidepressants, certain hormones like (progestin and synthetic estrogen), and Accutane (prescribed for acne), and antibiotics (i.e.: Streptomycin, Tetracycline, and Efavirenz) which can cause discoloration of tooth enamel -antihypertensive drugs like ACE inhibitors can result in neonatal renal failure, heart problems, and death -thalidomide was prescribed to women to prevent morning sickness but resulted in birth defects -non-prescription drugs that can be harmful include diet pills and aspirin Psychoactive Drugs -act on the nervous system to alter states of consciousness, modify perceptions, and change moods -e.g.: caffeine, alcohol, nicotine, illicit drugs 1) Caffeine -woman who had more than 200mg of caffeine had in increased risk of miscarriage 2) Alcohol -fetal alcohol spectrum disorder (FASD) are abnormalities and problems that appear in the offspring of mothers who drink alcohol heavily during pregnancy -abnormalities include facial deformities and defective limbs, face, and heart -children with FASD are likely to have learning problems and many are below average intelligence -FASD occurs more often than either Down Syndrome or Spina Bifida -first nations have an above average occurrence of FASD -alcohol use varies by age (older mothers drink more than younger mothers) and by province (4.1% in Newfoundland compared with 17.7% in Quebec) -it is recommended not to drink any alcohol during pregnancy or when trying to become pregnant 3) Nicotine -younger women were more likely than older women to smoke while pregnant -BC and ON report the 2 lowest rates of pregnant women smoking while Nunavut and NWT report the 2 highest rates -risks include preterm births, low birth weights, fetal and neonatal deaths, respiratory problems, sudden infant death syndrome, etc. -prenatal exposure to cigarette smoking during pregnancy is related to increased incidence of ADHD 4) Cocaine -cocaine use during pregnancy is associated with reduced birth weight, length, and head circumference, lower arousal, less effective self-regulation, higher excitability, and lower quality of reflexes at 1 month of age -impaired motor development at 2 years of age -slower rate of growth at 10 years of age -impaired language development and information processing -results may not be exact as other factors in the lives of pregnant women who use cocaine (i.e.: poverty, malnutrition, and other substance abuse) often cannot be ruled out as possible contributors to the problems -e.g.: cocaine users are likely to smoke cigarettes and consume other drugs 5) Methamphetamine -risks include high infant mortality, low birth weight, and developmental and behavioural problems, decreased arousal, increased stress, poor movement quality, etc. 6) Marijuana -prenatal marijuana exposure was related to lower intelligence in children, depressive symptoms at 10 years of age, and marijuana use at 14 years of age 7) Heroin -linked to withdrawal symptoms (i.e.: tremors, irritability, abnormal crying, disturbed sleep, and impaired motor control) in infants, behavioural problems, and attention deficits -continuous methadone treatment during pregnancy was linked to improved neonatal outcomes Incompatible Blood Types -if a pregnant woman is Rh-negative and her partner is Rh-positive, the fetus may be Rh-positive -the mother's immune system may produce antibodies that will attack the fetus which can result in miscarriage or stillbirth, anemia, jaundice, heart defects, brain damage, or death -generally, the first Rh-positive baby of an Rh-negative mother is not at risk but each subsequent pregnancy increases the risk -RhoGAM vaccine may be given within 3 days of the first child's birth to the mother to prevent her body from making anti-bodies that will attack Rh-positive fetuses Environmental Hazards -an embryo or fetus may be harmed if the mother's diet includes toxins such as mercury (from big fish who accumulate heavy metals) or if the father's exposure to certain chemicals causes changes in sperm -specific hazards include radiation, toxic wastes, and chemical pollutants -radiation can cause gene mutations (abrupt, permanent change in DNA); a routine diagnostic X- ray of the body is considered safe -environmental pollutants and toxic wastes such as carbon monoxide, mercury, and lead -early exposure to lead affects children's mental development -health policies should strive to eliminate all lead exposure Maternal Diseases -rubella causes prenatal defects by affecting organogenesis; women should be blood tested before they become pregnant to determine if they are immune to the disease -syphilis is damaging later in prenatal development (4 or more months after conception) -syphilis damages organs after they have formed -i.e.: eye lesions / blindness and skin lesions -genital herpes can be contracted by newborns when they are delivered through the birth canal of the mother with genital herpes -may lead to brain damage or death -cesarean sections can be performed to keep the virus from infecting the newborn -HIV / AIDS can infect her offspring: 1) during gestation across the placenta 2) during delivery through contact with maternal blood or fluids 3) postpartum through breast feeding (especially problematic in developing countries) -babies born to infected mothers can be: -infected and symptomatic -infected and asymptomatic -not infected -diabetes affects metabolism and is caused by the inability of the body to properly absorb sugar and starch from the blood -a women may develop gestational diabetes during pregnancy -offspring of diabetic mothers are at risk for metabolic disease -chronic and gestational diabetes were significant risks for cesarean delivery and preterm birth Maternal Age -adolescent women and women 35 or older are of special interest when discussing possible harmful effects on the fetus and infant -rate of still birth is elevated for adolescent girls and women 35 years and older -adolescents are the least likely of woman in all age groups to obtain prenatal assistance Diet, Nutrition, and Exercise - a developing embryo / fetus depends on the mother for nutrition which comes from the mother's blood -the nutritional status is determined by the mother's total caloric intake and her intake of proteins, vitamins, and minerals -children born to malnourished mothers are likely to have physical disabilities -maternal obesity may cause fetal death; the risk of stillbirth or neonatal death is doubled -maternal obesity is linked with problems in the CNS and spina bifida -overeating by pregnant women results in neuroendocrine changes in the fetus that program the development of fat cells and appetite regulation system -this is linked to being overweight in childhood and adolescence -folic acid (B-vitamin complex) is important for normal prenatal development -lack of folic acids is linked with neural tube defects -maternal use of folic acid and iron during the first month of pregnancy was associated with lower risks of Down Syndrome in offspring -0.4 to 1.0 mg of folic acid per day is recommended -those with high risk of having a child with neural tube defects should take 4 to 5 mg of folic acid per day (in its pure form) -orange juice and spinach are rich in folic acid -fish may have increased pollution -when mercury falls in the water, it can become toxic and accumulate in large fish such as sharks, swordfish, king mackerel, and large tuna -mercury is easily transferable across placenta -it is recommended to eat up to 2 fish per week of fish and shellfish that are lower in mercury (i.e.: salmon, shrimp, tilapia, light tuna, pollock, haddock, etc.) -PCB (polychlorinated biphenyls) are present in landfills, sediments, and wildlife -PCB polluted fish pose risks to prenatal neurodevelopment -Inuit infants in Nunavut have much higher levels of PCBs in their umbilical cords due to the large amounts of fish and marine animals eaten by their mothers -exercise is important during pregnancy -helps prevent excessive weight gain -helps maintain muscle fitness -ensues heart fitness -prevents varicose veins and deep vein thrombosis -offsets the risk of gestational diabetes Emotional States and Stress -physiological changes may occur in a woman when she experiences intense fear, anxiety, and other negative mood states which may affect her fetus -maternal stress may increase levels of corticotropin-releasing hormone which is a precursor to the stress hormone cortisol -elevated levelsof CRH and cortisol have been linked to premature deliveries in infants -a mother's stress may influence the fetus indirectly by increasing the likelihood that the mother will engage in unhealthy behaviours such as drugs and engaging in poor prenatal care -a mother's emotional state impacts the birth process -an emotionally distraught mother might have irregular contractions and a more difficult labor, which can cause irregularities in the supply of oxygen to the fetus -high maternal stress has long-term consequences -pregnant women with high levels of stress are at increased risk for having a child with emotional or cognitive problems, ADHD, and language delay -optimistic women have less adverse outcomes than pessimistic pregnant women -optimists believe they have control over the outcomes of their pregnancies Paternal Factors -age and exposure to environmental hazards (including exposing the mother and fetus to second hand smoke) influences prenatal and child development -exposure to lead, radiation, pesticides, and petrochemicals may cause abnormalities in sperm that lead to miscarriage, diseases like childhood cancer, etc. -low levels of vitamin C in fathers is linked to birth defects and cancer -taking cocaine may cause its attachment to sperm and cause birth defect; cocaine may be related to low sperm count, low motility, and abnormal sperm -exposure to secondhand smoke is related to lower infant birth weights and preterm delivery, wheezing, and bronchitis -younger women are more likely to be exposed to second hand smoke than older, pregnant women -the father's age is important -5% of children with old fathers have Down syndrome -offspring are at risk of birth defects like dwarfism and Marfan syndrome (head and limb deformities) Prenatal Care -involves medical care services in a defined schedule of visits -prenatal programs include comprehensive educational, social, and nutritional services -includes screening that can reveal manageable conditions and/or treatable diseases -provides education about pregnancy, labour, and delivery -prenatal care links women in poverty to other social services -women who receive prenatal care are more likely to seek preventative care for their infants -health care systems, provider practices, and individual and social characteristics may cause inadequate prenatal care -e.g.: a third of Canadian women who live in rural areas find accessing advanced maternity care difficult -e.g.: lack of transportation and child care, financial difficulties, etc. are common barriers to prenatal care -motivating positive attitudes towards pregnancy is important -women who have unplanned / unwanted pregnancies or have negative attitudes about being pregnant are more likely to delay or avoid prenatal care -in Scandinavia and Western Europe, more consistent, higher-quality prenatal care is provided than in North America Birth Stages of Birth -the birth process occurs in 3 stages First St
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