CH 8 Book and Lecture Notes
CH 8 Book and Lecture Notes Biol360
Cal State Fullerton
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Date Created: 05/15/16
CH. 8 pg 243267 BOOK NOTES (WEEK 13) PREGNANCY AND CHILDBIRTH A postmenopausal woman can become pregnant with the aid of reproductive technology: donated ova can be fertilized in vitro (usually with her husbands sperm) and the embryos placed in her uterus The pregnancy must be supported with hormone treatments More than 50% of all human embryos are genetically abnormal and have little or no chance of giving rise to a viable child Most of these defects occur at the very earliest stages of development If the ovum is fertilized by two sperm rather than one, for example, the resulting embryo will have three sets of chromosomes rather than the normal two In some cases, environmental factors such as alcohol consumption, general anesthesia, or x ray exposure at around the time of ovulation may trigger chromosomal abnormalities The great majority of abnormal conceptuses are lost at some point in their development Many fail to implant and the mother is never aware of their existence Others implant briefly, causing a transient release of hCG and a slight prolongation of the postovulatory phase, but then die, so that menstruation ensues Of pregnancies that proceed far enough to be detected clinically about 20% are subsequently lost by spontaneous abortion, usually during the first 3 months At least 1 in 2 of all spontaneously aborted embryos and fetuses has a chromosomal abnormality, whereas only 1 in 200 live born babies has one One major cause of fetal loss is blood group incompatibility, especially when the fetus possesses the blood group known as Rh FACTOR and the mother does not Rh factor is a molecular label on the surface of red blood cells In cases of Rh incompatibility the fetus will have inherited the factor from its father The combination of Rh negative mother and Rh positive father is common – it is the case for about 10% of all couples in the US but only a minority of their pregnancies are marked by problems These problems arise when the mother develops antibodies against Rh and those antibodies cross the PLACENTA and attack the fetus This does not happen routinely, because the fetus is immunologically isolated from the mother. Nevertheless, the mother may develop antiRh antibodies at childbirth if the fetus bleeds into the maternal circulation during delivery These antibodies develop too late to affect that child, but they may attack a subsequent fetus, destroying its red blood cells and rendering it severely anemic Such an attach can kill the fetus or newborn child, or it can leave the child intellectually disabled The initial immune response to a mother’s first Rh –positive fetus can be blocked by the administration of an antibody that binds to Rh and hides it from the mother’s immune system If severe anemia does occur in a subsequent pregnancy, the fetus or the newborn child may have to receive a blood transfusion Another serious condition that causes fetal loss is ECTOPIC PREGNANCY , which is an implantation of the fetus at a location other than the uterus This happens in about 1% of all pregnancies The most common site of ectopic pregnancy is the OVIDUCT (in which case it is called a “TUBAL PREGNANCY”) But other possible sites include the cervix, the ovary, and elsewhere within the abdominal cavity ECTOPIC PREGNANCIES can be caused by CONGENITAL MALFORMATIONS of the oviducts or uterus, by damage to the oviducts resulting from PID or APPENDICITIS or by treatment with certain sex steroids and contraceptives that interfere with the normal movement of the embryo into the uterus Ectopic pregnancies may occur without any of these predisposing factors, however The rate of ectopic pregnancy is increasing and the main culprit is the increasing prevalence of PID due to chlamydia infections Ectopic pregnancies commonly leads to early spontaneous abortion. Alternatively, as the embryo grows, it may cause internal hemorrhage or rupture of an oviduct, both of which are emergencies that threaten a mother’s life Recognition of the condition is hampered by the fact that the woman may not know she is pregnant The symptoms can appear within 3 weeks of the beginning of the pregnancy Therefore, if a woman of childbearing age has engaged in coitus recently and experiences abdominal pain, shoulder pain, pain on defecation or urination, abnormal vaginal bleeding, or signs of shock, she should see a doctor without delay HOW LONG DOES A NORMAL PREGNANCY LAST? Logically, we would time pregnancy from fertilization, or perhaps from implantation, but neither of these events can be used for timing because they don’t usually make themselves known to the mother The only relevant date that the mother is likely to remember is the onset of her last menstrual period, which occurs about 2 weeks before fertilization Thus pregnancy is conventionally times from that date, and the fetus is said to have a GESTATIONAL AGE, which is calculated based on the number of weeks that have elapsed since the onset of her last menstrual period even though the embryo didn’t actually exist for the first 2 weeks of that time. GESTATIONAL AGE: a fetus’s age timed from the onset of the mother’s last menstrual period According to the oftcited NAEGELE’S RULE, a pregnant woman’s due date is 9 months plus 1 week (ABOUT 281 days) after the onset of her last menstrual period The true average is probably 3 to 8 days longer than this, and it is longer for a woman’s first pregnancy than for later pregnancies Eighty percent of natural births occur within 2 weeks before or after the due date. NAEGELE’S RULE: a traditional rule for the calculation of a pregnant woman’s due date: 9 calendar months plus 1 week after the onset of the last menstrual period In the context of prenatal care, pregnancy is usually divided into three trimesters, each 3 months long TRIMESTER: one of three 3 month division of pregnancy These time periods do not correspond to any particular biologically significant milestones but are simply convenient ways to refer to early, middle, and late pregnancy The growth and appearance of the fetus over the first half of pregnancy is OVUM from week 12 EMBRYO from week 38 FETUS from week 918 Last menstrual period (week 1) Ovulation (week 2) Implantation (week 3) Frist missed period (week 4) Second missed period (week 8) GESTATIONAL AGE (weeks 1318) FIRST TRIMESTER IS period of MAJOR CHANGES The first trimester is in many ways the most significant period of pregnancy During this time the embryo implants in the uterine wall and sets up a system of hormonal and metabolic communication with the mother The implanted embryo secretes hCG, which prevents the corpus luteum from regressing and therefore keeps progesterone levels high Later, the embryo and placenta themselves secrete estrogens and progesterone These hormones enter the mother’s circulation, eventually rising to levels not experienced at any other time of her life Their main role is to sustain the endometrium, but they also prepare the uterine musculature for childbirth and the breast for lactation During the first 8 weeks of GESTATIONAL AGE (which is the 6 weeks after fertilization) the embryo develops form a tiny, featureless disk of cells into a miniature human being with all its organ systems present It is not referred to as a fetus By the end of the first trimester the fetus is about 4 inches (10 cm) in its longest dimension (crownrump length) and weighs about 2 ounces (50g) The external genitalia have differentiated as male or female, and most of the fetus’s organ systems are functioning at some primitive level The first trimester is an important period for the mother as well She typically learns that she is pregnant, a piece of news that may bring delight or anxiety If she keeps the child, she is most likely to experience some of the early symptoms of pregnancy, especially breast tenderness and morning sickness Breast tenderness is a sign that the breasts are preparing for nursing (breast feeding) the infant, even though it will be months before they can actually function Morning sickness affects about half of all pregnant women, but it varies in degree from mild nausea upon awakening to persistent and even lifethreatening vomiting It is often associated with aversions to certain foods, especially strongtasting foods and animal products (meats, eggs, and fish) Eating bland food tend to alleviate the condition, which usually disappears by the end of the first trimester Other symptoms experienced by many women during the first trimester include frequent urination, tiredness, sleeping difficulties, backaches, mood swings, and sometimes, depression The woman’s male partner may develop analogous symptoms and may even gain weight faster than the pregnant woman The phenomenon of pregnancylike symptoms in men is known as COUVADE The average woman gains only about 24 lbs during the first trimester Numerous studies have shown that almost every aspect of pregnancy benefits from PRENATAL CARE (medical care and counseling provided to pregnant women) during the first trimester It decreases the likelihood of maternal, fetal, or neonatal death; fetal prematurity; and low birth weight Unfortunately, prenatal care is not as widely utilized in the US as it is in European countries African American, Hispanic, poor, unmarried, uneducated, and teenage women are particularly likely to miss out on firsttrimester care and to receive inadequate care at later times in their pregnancies The reasons women receive inadequate care have to do with psychosocial factors, such as ambivalence about the pregnancy or not believing that prenatal care will be helpful, more than a lack of access to such care Ideally, prenatal care beings at least 3 months BEFORE a woman becomes pregnant This preconception care can be summed up in five core precepts PRECONCEPTION CARE: Medical care and counseling provided to women before they become pregnant take 400 mcg (micrograms) of folic acid daily to reduce the risk of birth defects Stop smoking and stop drinking alcohol Be sure that any medical conditions (e.g diabetes and obesity) are under control and that vaccinations, especially for RUBELLA, are up to date. Get tested for HIV RUBELLA: German Measles, a viral infection that can cause developmental defects in fetuses whose mothers contract the disease during pregnancy Discussing with your doctor all medications and supplements that you are taking Avoid exposure to toxic or infectious substances at work and at home Its important to take care of these issues before pregnancy, not only because they take time to deal with, but also because some of them are relevant to the very earlies weeks of development, when a woman may not know that she is pregnant at all. Therefore, if there is a chance that she will become pregnant, she should act as if she IS pregnant The first healthcare visit after conception typically takes place soon after the first missed period. At this point the healthcare provider takes a history and does a general examination, a pap smear, a cervical culture, (to test for gonorrhea and other conditions), a rubella test (if not done previously) and a test for blood type and Rh factor A clinical pregnancy test may be done, even if the woman has already done a home pregnancy test The provider advises the woman on nutrition and related matters, answers her questions, and helps her make informed decisions about how to manage her pregnancy and childbirth On one or more occasions during the first trimester, the provider conducts a pelvic exam In addition to the pelvic exam, many providers perform an ultrasound exam at some point during the first trimester, especially if there is some indication of a problem This exam permits determination of fetal age, the number of fetuses, and the presence of any abnormality such as ectopic pregnancy It is not usually possible to discern the fetus sex by ultrasound during the first trimester The distribution of extra weight for a woman who gains 28.8 pounds during pregnancy PREGNANCY WEIGHT UNDERWEIGHT <18.5 BMI (Recommended weight gain at term 2840 lbs) NORMAL WEIGHT 18.624.9 BMI (Recommended weight gain at term 2535 lbs) OVERWEIGHT 2529.9 BMI (Recommended weight gain at term 1525 lbs) OBESE >30.0 (Recommended weight gain at term 1120 lbs) An expectant mother needs an extra 250 to 300 calories per day in addition to what she needs to support herself At term (just before childbirth) a woman typically weighs 2035 pounds above her pregnancy weight This includes the weight of the fetus, placenta, and amniotic fluid, as well as her own increased fat deposits, enlarged breasts, and increased volume of blood and tissue fluids Make sure the mother is taking an adequate amount of folic acid, calcium, and iron Women who begin pregnancy with normal weight are most likely to give birth to a healthy child Obese women pregnancy disorders: diabetes and hypertension Alcohol consumption increases the likelihood of birth defects and infant mortality, and it is associated with a specific cluster of symptoms known as FETAL ALCOHOL SYNDROME Children with this syndrome are small, have a characteristic facial appearance, and suffer from cognitive and behavioral problems that persist into adulthood Caffeine can also be harmful: a daily intake of 200 mg or more doubles the risk of miscarriage Smoking is one of the most harmful practices a woman can engage in during pregnancy It increases the likelihood of spontaneous abortion, premature birth, low birth weight, and congenital malformations. Its ill effects continue after a child is born One third of all cases of sudden infant death syndrome can be attributed to the mother’s smoking during pregnancy Many drugs including prescription, over the counter, and street drugs, can harm the fetus A particularly dangerous drug is ISOTRETINOIN (ACCUTANE and its generic equivalents) which is used for the treatment of severe acne Accutane causes fetal malformations, AGENT AND POSSIBLE FETAL CONSEQUENCES ALCOHOL fetal alcohol syndrome TOBACCO spontaneous abortion, premature birth, low birth weight, addiction of newborn, and or sudden infant death ISOTRETINOIN (ACCUTANE) heart, brain malformations, intellectual disability THALIDOMIDE limb defects; deafness, blindness VITAMINS A and D ( in excessive amounts)fetal malformations ANDROGENS, ESTROGENS abnormalities of external genitalia and reproductive tract, especially in females DIETHYLSTILBESTROL (DES) reproductive cancers (females); reduced fertility (males) ASPIRIN (late in pregnancy)interference with blood clotting, potentially causing hemorrhage in mother, fetus, or newborn STREET DRUGS ( heroin, methamphetamine, cocaine) – spontaneous abortion; low birth weight, respiratory depression of newborn, addiction to newborn MARIJUANA possible impairment of neuronal survival in fetal brain INFECTIONS RUBELLA damage to ears, eyes, heart GENITAL HERPES spontaneous abortion, premature birth, or birth defects HIV AIDS in infancy/childhood CHLAMYDIA premature birth; neonatal eye infection PHYSICAL AGENTS X RAYS increased risk of childhood cancer NUCLEAR RADIATION increased risk of childhood cancer COSMIC RADIATION (high altitude flight for air crew or very frequent flyers) – possible increased risk of childhood cancer ) HIGH BODY TEMP (OVER 100.4 F) IN EARLY PREGNANCY (FROM FEVER , excessive exercise, saunas, hot tubs) a variety of birth defects SECOND TRIMESTER (THE EASIEST =) The second trimester begins at 13 weeks of gestational age Most women experience the second trimester as a period of calm and well being Morning sickness and most of other unpleasant symptoms of early pregnancy usually disappear. Only the need for frequent urination persists, and in fact may become worse as the enlarging of the uterus presses on the bladder Signs of pregnancy becomes obvious; the abdomen swells, stretch marks may begin to appear, and the breasts may release small amounts of colostrum, the special kind of milk that nourishes newborn infants (COLOSTRUM) Around the middle of the second trimester the mother will begin to feel the fetus’s movements This event is known as QUICKENING and has always had great psychological significance It is a major step in the mother’s bonding with her child In early Christian doctrine, quickening was thought to be the time the soul entered into the fetus, so that abortion before quickening was not necessarily a sin The beginning of fetal movement does not mean that the fetus is now a conscious being, however The cerebral cortex, which is probably the main locus of consciousness, is still at an extremely rudimentary stage of devndopment at the time of quickening The tests that are done during the 2 trimester: ultrasound scans, amniocentesis, and chorionic villus sampling. These procedures can also be used to determine the fetus’ sex An ultrasound scan at the beginning of the second trimester or slightly earlier can reveal evidence suggestive of congenital abnormalities, including Down syndrome When the ultrasound is combined with biochemical tests, about 90% of fetuses with down syndrome can be identified If there are reasons to be concerned about fetal abnormalities, such as advanced maternal age or a history of abnormalities in previous pregnancies, more invasive tests may be recommended In AMNIOCENTESIS (the sampling of the amniotic fluid for purposes of prenatal diagnosis) the doctor first determines the precise position of the uterus and the fetus with an ultrasound scan and then passes a thin needle through the front wall of the abdomen into the amniotic sac in which the fetus is floating, avoiding the fetus itself A sample of amniotic fluid, containing some freefloating cells derived from the fetus or its membranes, is withdrawn The info gained through amniocentesis allows for the identification of chromosomal and genetic abnormalities as well as SPINA BIFIDA (incomplete development of the spine and spinal cord) AMNIOCENTESIS is usually done 15 to 18 weeks of pregnancy, but it is sometimes done as early as 11 weeks and it carries a slight risk of causing a miscarriage CHORIONIC VILLUS SAMPLING: the sampling of tissue from the placenta for purposes of prenatal diagnosis In this procedure, a catheter is passed through the cervix, and a sample of tissue is taken from the placenta Chorionic villi are the highly branched tissue projections from the placenta that serve to increase the area of contact with the mother’s blood The procedure may also be done with a needle inserted through the abdominal wall Chorionic villus sampling is usually done at10 to 12 weeks of pregnancy Although it has the advantage of producing results earlier than amniocentesis, chorionic villus sampling identifies only chromosomal and genetic abnormalities, not spina bifida, and the risk of harm to the fetus, is slightly higher than amniocentesis Moderate exercise benefits the mother The frequency of sexual activity tends to decline during pregnancy, but for most women there is no health reason for abstaining for coitus THIRD TRIMESTER Begins at 27 weeks of gestational age, At this time, the fetus already weights about 2 pounds And has a decent chance of surviving if born prematurely Although its survival would entail weeks of intensive neonatal care and a six figure hospital bill BRAXTON HICKS CONTRACTIONS: irregular uterine contractions that occur during the third trimester of pregnancy. Also called FALSE LABOR PLACENTA PREVIA: an abnormally low position of the placenta, so that it partially or completely covers the internal opening of the cervix INCOMPETENT CERVIX: a weakening and partial opening of the cervix caused by a previous traumatic delivery, surgery, or other factors In the third trimester both the parents and the fetus make preparations for birth Childbirth classes teach strategies to facilitate delivery and to minimize pain LABOR HAS 3 STAGES 1. The uterine contractions and cervical softening to prepare the birth canal for the passage of the fetus 2. The fetus passes through the canal and is “delivered” Rapid physiological changes adapt it to an airbreathing existence 3. The placenta (afterbirth) and fetal membranes are expelled It has been widely thought that sex late in pregnancy may increase the likelihood of premature children, but research indicates it does not The foregoing applies to normal pregnancies The following medical conditions make coitus unwise, especially toward the end of pregnancy Threatened miscarriage or premature birth Unexplained vaginal bleeding Leakage of amniotic fluid Placenta previa: a condition in which the placenta covers the cervix Incompetent cervix: in which the cervix opens too early Difficult births may necessitate surgical widening of the vaginal opening (EPISIOTOMY) Or delivery via abdominal incision (CESAREAN SECTION) In the US, episiotomy is performed less often than in the past But c sections are increasingly common. Various forms of anesthesia are available if labor is excessively painful Methods of pain relief that do not rely on medications are also available Premature or delayed labor is associated with increased risk of harm to the fetus The period after birth (POSTPARTUM) is a time of recovery for the mother but is marked by depression with disordered thinking in a few women The birth of child, especially the first one, can bring great happiness, but it also causes major stresses Marital satisfaction tends to decline after the transition to parenthood, and the frequency of sexual activity decreases Hormones prepare the mother’s breasts for lactation and mediate the release of milk during breast feeding The content of milk changes during the weeks after childbirth Breast feeding has significant advantages over formula feeding But formulafed infants can thrive too LAMAZE METHOD: a method of childbirth instruction that focuses on techniques of relaxation and other natural means of pain reduction BRADLEY METHOD: a method of childbirth instruction that stresses a partners role as birth coach and that seeks to avoid medical interventions GLYCOGEN: a polymer of glucose used for energy storage PARTURITION: delivery of offspring childbirth LABOR: THE PROCESS OF CHILDBIRTH Much of this preparation for birth is orchestrated by increasing amounts of corticosteroids secreted by the fetus’s adrenal glands during the third trimester Among their effects are important changes in the lungs that facilitate their inflation with air when the newborn takes its first breath CORTICOSTEROIDS also instruct the fetus’ liver to manufacture GLYCOGEN that will be used to supply the brain’s critical glucose needs before, during, and just after birth Rising corticosteroid levels before birth also affect blood production, switching the hemoglobin in red blood cells to a different form that is better suited to an air breathing lifestyle BEFORE LABOR BEGINS: the fetus changes its position in the uterus, as its head sinks deep into the pelvis against the cervix st 1 STAGE VOCAB ENGAGEMENT: the sinking of a fetus’ head in to a lower position in the pelvis in preparation for birth also called lightening CONTRACTION, in childbirth a periodic coordinated tightening of the uterine musculature , felt as a cramp SOFTENING: the elimination of connective tissue from the cervix allowing it to thin out and dilate during labor. Also called ripening BIRTH CANAL: the canal formed by the uterus, cervix, and vagina, through which the fetus passes during the birth process EFFACEMENT: the thinning of the cervix in preparation for childbirth DILATION: in childbirth, the expansion of the cervical canal. Also called dilatation TRANSITION: the final phase of dilation of the cervix during labor EPIDURAL ANESTHESIA: ANESTHESIA administered just outside the membrane that surrounds the spinal cord 2 stage VOCAB CROWNING: the appearance of the fetal scalp at the vaginal opening EPISIOTIOMY: a cut extending the opening of the vagina backward into the perineum, performed by an obstetrician with the intention of facilitating childbirth or reducing the risk of perineal tear Women usually feel an urge to push “or bear down” The compression of the fetus chest as it passes through the canal effectively “squeegees” the fluid out of its lungs thus preparing them for their breath. rd 3 stage VOCAB AFTERBIRTH: the placenta, whose delivery constitutes the final stage of labor CESAREAN SECTION ( C SECTION) the delivery of a baby through an incision in the abdominal wall and the uterus PREMATURE BIRTH: birth that occurs more than 3weeks before a woman’s due date. Also called preterm birth DELAYED LABOR: labor that occurs more than 3 weeks after a womans due date INDUCED LABOR: labor induced artificially by drugs POSPARTUM: the period after birth LOCHIA: a bloody vaginal discharge that may continue for a few weeks after childbirth POSTPARTUM DEPRESSION: depression in a mother during the postpartum phase DEPRESSIVE PHYCHOSIS: depression accompanied by seriously disordered thinking BREASTFEEDING LACTATION: the production of milk in the mammary glands PROLACTIN: a protein hormone secreted by the anterior lobe of the pituitary gland, that promotes breast development, among other effects MILK LET DOWN REFLEX: the ejection of milk into the milk ducts in response to suckling. Also called milk ejection reflex COLOSTRUM: the milk produced during the first few days after birth; it is relatively low in fat but rich in immunoglobulins . thick, yellowish special milk Wet nurse: a woman who breastfeeds someone else’s infant INFANT FORMULA: manufactured breast milk substitute Breast feeding has more advantages than bottle feeding Health benefits for the baby. These babies are less likely to develop infectious illnesses such as pneumonia, botulism, bronchitis, bacterial meningitis, staphylococcal infections, influenza, ear infections, rubella, and diarrhea, and they are also less prone to asthma Heath benefits for the mother is the release of oxytocin, breastfeeding helps shrink the uterus to its pregnancy size and reduces postpartum bleeding. Psychological benefits to the mother and infant Convenience and expense Contraceptive effect MASTITIS: inflammation of the breast LECTURE NOTES Fertilization occurs in oviduct, and it becomes a zygote then cell division and development begin CLEAVAGE: first few cell divisions from the zygote. Starts 30 hours to third day Mitotic cell division creates more cell Each cell are called BLASTOMERE MORULA appears on the 3 of 4rth day and is a solid ball of 16 or more cells Then it will be a hollow cell BLASTOCYST. This will embed in the uterus. Wall of uterus becomes highly vascularized Group of cells within the hollow space forms the inner cell mass (ICM) DEVELOPS INTO THE EMBRYO The cells around the ICM become the EXTRAEMBRYONIC MEMBRANES. Role in implantation supports embryos growth Progesterone production increases because of implantation of embryo It takes about a week for the embryo to fully implant into the uterus At the time of implantation, the outer cells of the blastocyst begin to produce human chorionic gonadotropin hCG the “pregnancy hormone” GASTRULA: in the second week of development, the inner cell mass flattens into a 2 layer disk (ECTODERM AND ENDODERM) Shortly after, a third layer forms between the others (MESODERM) At this point, the fate of many of the cells is predetermined Ectoderm: part of the skin Mesoderm: muscle and connective tissue Endoderm: lining of the digestive tract and some of the inner organs EARLY STAGES OF EMBRYONIC DEVELOPMENT CLEAVAGE: ZYGOTE 2 CELL EMBRYO MANY CELLED SOLID BAL GASTRULATION: BLASTOCYST (CROSS SECTION) GASTRULA (CROSS SECTION) ECTODERM, MESODERM, ENDODERM PLACENTA takes 10 weeks to form and secretes hormones that maintain the pregnancy It also allows material to pass between the mother and fetus (blood odes not circulate directly from mother through the fetus) Placenta is attached to the uterine wall Mothers arteries and veins are close to the umbilical chord. The mothers blood does not mix with the fetus Embryo within the first 8 weeks of development Tissues and organs are still developing And (these are the differences) Fetus development form 9 weeks until birth Organs are in place FIRST TRIMESTER The embryo secretes HUMAN CHORIONIC GONADOTROPIN (HCG) which causes: Maintenance the corpus luteum Increased mucus in the cervix Growth of maternal part of the placenta Enlargement of the uterus Cessation of ovarian and menstrual cycling Breasts enlarge rapidly Urine detects hCG. The pregnancy test is looking for hCG. Detects as early as 10 days after ovulation, but more reliable 15 days after Blood test more sensitive and detect 8 days after ovulation We have to wait for implanation before we take tests EARLY PREGNANCY SYMPTOMS: Amenorrhea, morning sickness, frequent urination, tender swollen breasts ORGANOGENESIS: occurs during the first trimester. The formation of organs is prior to this. The heart starts beating at week 4 By week 8 all major structures are present in rudimentary form The rapidity of development makes this a time when the embryo is especially sensitive nd 2 TRIMESTER Fetus grows rapidly and is very active Hormonal levels stabilize as hCG declines Morning sickness is at its worst in the first trimester with hCG levels high Corpus luteum deteriorates, the placenta takes over Placenta secretes progesterone which maintains the pregnancy 3 TRIMESTER Fetus grows rapidly. In the fat layer and brain layer Fetal activity may decrease as the fetus fills the space available to it Maternal abdominal organs becomes compressed and displaced TWINS: DIZYGOTIC TWINS: two ova + two sperm Same genetic relation as any sibling. (fraternal twins) MONOZYGOTIC TWINS: One ovum+one sperm Developing embryo splits during early development (same dna, identical twins) CONJOINED TWINS: the embryo divides too late to develop into two individuals between days 13 and 15 Each girl has her own head, heart, stomach, and gallbladder They share liver, bloodstream, and lower abdominal organs, They have 3 kidneys and 3 lungs Sex is determined at conception, but difference between sexes do not appear until week 6 when sex hormones begin to be secreted Differences between males and females cannot be seen on ultrasound until 1215 wweeks Organs develop at different times : a critical period During this, an organ is vulnerable to toxin, viruses, and genetic abnormalities Altering the normal development may cause birth defects Taratogin? TRIPLE SCREEN OR QUAD SCREEN TEST: blood test that looks for chemical markers (ALPHA FETOPROTEIN test) ULTRASOUND IMAGING AMNIOCENTESIS EMBRYOSCOPY POST TERM PREGNANCIES: late pregnancy, baby grows and pelvis may not accommodate After 40 weeks placenta may not deliver nutrients 1 stage of labor: dilation and effacement EARLY ACTIVE LABOR ACTIVE LABOR TRANSITION (short, about an hour) dilation last 3 cm of it Process of giving birth: hormones estrogen form the ovaries induces oxytocin receptors on uterus POSITIVE FEEDBACK LOOP: the more oxytocin produced, the more is made, the stronger the contractions get. This builds up Oxytocin from fetus and pituitary stimulates uterus to contract, stimulates placenta to make PROSTAGLANDINS which stimulates more contractions of uterus then positive feedback EXPULSION: when the baby is pushed through. 1 stage is 1224 hours 2 stage is around an hour only EPISIOTOMY: a cut in the perineum during delivery Occurs in ~50% of deliveries Third stage is placenta separating from wall of uterus 25% of babies done by c section Surgical incision in abdominal wall and uterus Performed when: Vaginal delivery too demanding No time to induce Baby too large or positioned wrong Medical emergency Placenta blocking cervix PAIN MANAGEMENT: Most common: epidural IV pain medication The LAMAZE METHOD THE BRADELY METHOD Childbirth settings: hospital and birthing center (for natural births with midwives staff), home birth, midwive (trained in childbirth but not a doctor) Mature breast milk: 90% water 7% sugar (lactose) 36% fat 0.80.9% proteins Amino acids Vitamins A, B1, B2, B12, C,D,E,K Energy content approx. 19 calories per fluid HORMONES: prolactin, secreted in constant amounts during the course of lactation, stimulated breasts to produce milk OXYTOCIN: stimulates breasts to eject milk, released in response to suckling Breastfeeding supply and demand
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