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Chapter 6

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Psychology 1000

Chapter 6; conception, pregnancy, and childbirth December-03-12 3:31 PM Conception Sperm meets egg; the incredible journey  Egg reaches the uterus in about 5 days if fertilized- otherwise, disintegrates in 48 hours  Cilia move the egg through (doesn’t move on its own)  Nucleus in head of sperm contains the DNA  Sperm also contain RNA carrying instruction for early embryotic development, and a large number of proteins  Acrosome (chemical reservoir) also in head of sperm  Midpiece contains mitochondria (where chemical reactions occur and provide energy- used when sperm lashes tail back and forth- flagellation  Sperm capable of swimming 1-3 cm per hour, but has been recorded that sperm have reached egg within 1.5 hours- muscular contractions in uterus may help them along  Conception typically occurs on the outer third of the fallopian tube (part near ovary)  Of 200 million sperm, about 2000 reach the tube containing the egg  Zona pellucida- thing, gelatinous layer surrounding the egg  Hyaluronidase; an enzyme secreted by the sperm that allows one sperm to penetrate the egg- produced by acrosome. It dissolves the zona pellucida o Conception has occurred!  Zygote; the fertilized egg. To about the second week of gestation  Zygote continues to travel down fallopian, and 36 hours after conception, it begins process of cell division  Mass of cells implants in uterus to be nourished and grow  Weeks 2-8; embryo  Fetus until birth Improving the chances of conception; making a baby  Sperm live inside women for up to 5 days  Egg capable of being fertilized for about the first 12 to 24 hours after ovulation  Intercourse should be timed at ovulation or one or two days before (allowing swimming time)  More sex is not necessarily more effective. Important for mans sperm count to be maintained  Takes at least 24 hours to manufacture 200 million sperm  Probably best to have sex every 24 to 48 hours, or about 4 times during the week in which the women is to ovulate  Prolonged abstinence (more than ten days) may result in low sperm quality  Best position is man on top missionary, and women should lie on her back for .5-1 hours afterwards to allow sperm to pool in vagina  Lubricants could kill sperm or block entrance Development of the conceptus  In the past, relationship between conceptus and pregnant women has been viewed as harmonious  New perspective- pregnancy is a silent struggle  Nature should favour the development of characteristics of each that would give it the edge in competitions for resources , enabling it to win (ie. Calcium struggles)  Gestational diabetes (women has high bs because body not able to make and use all insulin it needs, but appears during pregnancy) , and pre-eclampsia (occurs during 3rd trimester, sharp rise in bp, presence of protein in urine, and swelling of hands, feet, face) can support this new theory  1st trimester; 1-3 months  2nd trimester; months 4-6  3rd; months 7-9 The embryo and its support systems  After zygote implants, tendrils from zygote begin to penetrate the blood vessels in the wall of the uterus  Embryonic period of development (1st 8 weeks)- most major organ systems are formed  Inner part of ball of cells differentiates into 2 layers- endoderm and ectoderm. Then third forms- mesoderm (between them)  Ectoderm- forms the entire nervous system and skin  Endoderm- digestive system and respiratory system  Mesoderm- muscles, skeleton, connective tissues, and reproductive and circulatory systems  Cephalocaudal order of development- head develops first and lower part of the body last  Another group of cells differentiates into the trophoblast- maintains the embryo and will become the placenta  Placenta; organ formed on the wall of the uterus through which the fetus receives oxygen and nutrients and gets rid of waste products. It does this by producing tendrils that penetrate the blood vessels in wall of uterus- they form a separate structure as they grow  Women's and fetus circulatory system are completely separate  Fetus' blood passes out of body through the umbilical cord to the placenta - here is circulates in the villi (fingerlike projections in placenta), womens blood circulates outside of these villi  Membrane barrier between two blood systems  Some viruses and disease causing organisms can pass through- including those for German measles (rubella) and syphilis  Other drugs can cross too  Placenta also secretes hormones- estrogen and progesterone  Human chorionic gonadotropin (hCG); a hormone secreted by the placenta, it is the hormone detected in pregnancy tests  Umbilical cord; formed during the 5th week of embryotic development o Contains 3 blood vessels; two arteries and one vein o Attaches to the placenta, providing for interchanges of substances  Two membranes surround the fetus- chorion and amnion (innermost)  Amnion is filled with a watery liquid called amniotic fluid, in which the fetus floats and can readily move. Keeps fetus at constant temperature and protects it. This is the fluid tested when an amniocentesis is performed Fetal development during the first trimester  3rd week gestation- embryo appears as small bit of flesh and is about1/2 inch long  3rd and 4th weeks- head goes through development, central nervous system begins to form, and beginnings of eyes and ears  End of 4th week- backbone  Tail noticeable but it disappears after 8th week  4th-8th week-external body parts  End of 10th week- completely formed  End of 7th- liver, lungs, pancreas, kidneys and intestines have formed and begun limited functioning, gonads form  12th- gender not known until now  End of 12th (end of first trimester)- looks like small infant. 10cm long Fetal development during the second trimester  End of 14- movements detected  18th week- woman can feel movements  20th- opens eyes  24th- sensitive to light and can hear sounds in utero  Periods of wakefulness and sleep Fetal development during the third trimester  End of 2nd trimester, fetus' skin is wrinkled and covered with down like hair  Beginning of 3rd- fat deposits form, down like hair is lost  7th month- fetus turns to assume head down position  Breech presentation if this turning doesn’t occur by birth  Growth during last two months is rapid  Research from BC found that infants of European decent weighed significantly more than infants of Chinese or south Asian decent The stages of pregnancy The first trimester (the first 12 weeks) Symptoms of pregnancy  Illness and emotional stress can delay period  Can skip period for no apparent reason  Cyclic bleeding or spotting may occur- in a few cases it is a symptom of miscarriage  Basal body temperature can provide very early sign- if temperature rises abruptly at about the time that ovulation would occur and then stays up for more than two weeks, chances are good she is pregnant  Increased temperature- high level of progesterone manufactured by the corpus luteum and, later the placenta  Tenderness of breasts, tingling and sensitivity of nipples, nausea, vomiting, frequent urination, fatigue, and need for more sleep Pregnancy tests  Most common test is an immunologic test based on detecting the presence of hCG secreted by the placenta, in the womens urine  98-99% accurate  Lab test may give false negative if it is done too early or if errors are made in processing  Modern urine tests are 98% accurate 7 days after implantation (just when period is missed)  Beta-hCG radioimmunoassay- another type of pregnancy test- assesses the presence of beta- hCG in a blood sample. Can detect it at low levels- reliable for 7 days after fertilization. Much more expensive and available only in labs associated with hospitals or large clinics  Home pregnancy tests- claim that they are able to detect on the first day of the missed period.  Lab tests of 18 brands found that only one of the 18 detected low levels of hCG, and only 8 detected high levels of hCG. So 10 of the 18 would produce false negative  They also have 16% rate of false positives  Presumptive signs (amenorrhea, breast tenderness, nausea, etc.) probable signs (pregnancy tests), and positive signs (beating of fetal heart, active fetal movement, detection of fetal skeleton by ultrasound- cannot be detected until the 4th month, with exception to ultrasound- 1st trimester)  EDC-expected date of confinement (due date)  EDC calculated using 'nagele's rule'- to take the take of the first day of the last menstrual period, subtract 3 months, add seven days and finally add one year  Ultrasounds more accurate than the rule- used more often to revise the due date Physical changes  1st trimester- large increase in the levels of hormones, especially estrogen and progesterone- produced in placenta  Breasts swell and tingle- development of mammary glands which is stimulated by hormones  Nipples and areola may darken and broaden  Urinate more often due to pituitary hormones that affect the adrenals, which in turn change the water balance of body so that more water is retained, fetus also pushing against bladder  Cause of morning sickness and nausea is unknown o One theory is that vomiting causes women to expel foods containing toxic chemicals- supporting evidence includes lower rate of miscarriage among women who experience morning sickness. About 25% experience no vomiting at all  Vaginal discharge increase, partly because the increased hormone levels change the pH of the vagina and partly because he vaginal secretions are changing in their chemical composition and quantity  Fatigue and sleepiness probably related to high levels of progesterone, known to have sedative effect Psychological changes  One study compared 70 pregnant women (planned pregnancies) with 92 non-pregnant women. Found that pregnancy is neither a time of heightened well-being nor heightened emotional turmoil  Attitude toward pregnancy makes a difference- women who desire the pregnancy are less anxious than women who do not  Another factor is social class- several studies found low income is associated with depression during pregnancy. There also may be more unwanted pregnancies among low income women  Third influence is the availability of social support- more supportive partner, less likely to be depressed perhaps because the partner serves as a buffer against stressful events  1st trimester- nausea, associated with morning sickness and fatigue. Depression not uncommon during this time. Women's anxieties often centre on concerns about miscarriage The second trimester (weeks 13-26) Physical changes  4th month- aware of movements  Most physical symptoms of 1st trimester disappear, and discomforts are at a minimum  Constipation and nose bleeds (caused by increase blood volume)  Edema- water retention and swelling- may be a problem face, hands, wrists, ankles and feet  Mid-pregnancy- breasts under hormonal stimulation, have essential completed their development in preparation for nursing  Colostrum; a watery substance that is secreted from the breasts at the end of pregnancy and during the first few days of delivery- no milk yet (begins at 19th week) Psychological changes  Usually period of calm and well-being  Fear of miscarriage diminishes  Women who have had previous pregnancy are more distressed during this time than women who have not- may reflect the impact of the demands associated with the care of other children when one is pregnant  Feelings of nurturance, or maternal responsiveness to the infant, increase steadily from the pre-pregnant to postpartum period. Increase does not appear to be related to changes in hormone levels during pregnancy The third trimester (weeks 27-38) Physical changes  Pressure on other organs  Women who are slim should gain relatively more  Braxton- hicks contractions; contractions of the uterus during pregnancy that are not part of actual labour- painless, thought they may help to strengthen the uterine muscles, preparing them for labour  When head drops into pelvis- called lightening, dropping, or engagement- usually occurs during labour for women who have had babies before, and 2-4 weeks before birth for a women who hasn't Psychological changes  Patterns from earlier continue into the 3rd  Study in Montreal- women who reported more anxiety, daily hassles, and stress during pregnancy experiences more complications  First time mothers- experienced significant increase in dissatisfaction with their husbands from the 2nd to 3rd trimester  Another study- wives who reported higher levels of affection exchanged between husband and wife reported lower levels of anxiety and insomnia in 3rd trimester The fathers experience in pregnancy Physical changes  Indigestion, gastritis, nausea, change in appetite and headaches (couvade syndrome)  May be caused by hormonal changes in the male  Men and women displayed stage specific hormone differences, including high levels of prolactin prenatally and low levels of testosterone postnatally  Men with more pregnancy symptoms has high levels of prolactin prenatally  Couvades ritual; husband retires to bed while his wife is in labour and experiences all pains of delivery, moaning and groaning as she does- still practiced in Asia, South America, and Oceania Psychological changes  Men who showed higher levels of responsiveness to viewing videotapes and auditory and visual cues from newborns before birth, had higher levels of prolactin prenatally and lower levels of testosterone postnatally  Lower levels of testosterone may facilitate paternal behaviour Sex during pregnancy  For normal, health pregnancy, couples can continue to have intercourse until four weeks before the baby is due  No evidence that intercourse or orgasm is related to preterm labour  Study found that it was associated with reduced risk of preterm birth  Most common pattern is decline in frequency of intercourse during the 1st trimester, no variation in the 2nd, and even greater decline in 3rd- males reported same pattern  Side-side is the best position for later in the pregnancy Nutrition during pregnancy  In a study, those with poor diets had 7 times as many threatened miscarriages and 3 times as many stillbirths their labour lasted 5 hours longer on average  Protein- important for building new tissues  Folic acid- important for growth (folic acid deficiency- anemia and fatigue)  Need more iron because fetus draws off iron from the blood around placenta  Calcium deficiency- muscle cramps, nerve pains, uterine ligament pains, sleeplessness, irritability (can lead to increase in bp which could cause eclampsia)  Calcium and magnesium deficiency- associated with premature birth Effects of substances taken during pregnancy  Teratogen; a substance that produces defects in a fetus  Not all drugs can cross placenta barrier, but some can  Health Canada- maternal drinking is one of the leading causes of preventable birth defects and developmental delays in children  Survey- 15% of pregnant women drink some alcohol  Fetal alcohol syndrome (FAS); serious growth deficiency and malformations in the child (affects 1% of Canadians)  Tobacco use retards fetal growth and increases the risk of infant illness, disability, and death o Prematurity, low birth weight, cardiovascular anomalies, conditions involving arteries, veins or the heart, asthma o Lower than 23% smoke during pregnancy  Steroids, some antihistamines, long term use of antibiotics, excessive amounts of vitamin A,D,B6, and K, caffeine, antidepressant, lithium, cocaine and marijuana produce lower birth rate, complications and/or defects Dads and drugs  Drugs taken by the men before conception may also cause birth defects, probably because they damage the sperm and their genetic contents  Marijuana- reduced sperm count, more damaged sperm, and reduced fertility  One study found that fathers smoking during pregnancy in the absence of mothers smoking also increased risk (second hand) Birth The beginning of labour  May be discharge of small amount of bloody mucus (mucus plug that was in cervical opening- prevented germs from passing up vagina into uterus)  10% of women- membranes containing amniotic fluid rupture and gush of warm fluid (labour begins in 24 hours after this)  Its more common that it doesn’t rupture until the first stage of labour  Braxton-hicks contractions may increase before labour and be mistaken for labour (they are very irregular though)  Biological mechanism that initiates and maintains labour is not completely understood  Progesterone- withdrawal theory; progesterone is known to inhibit uterine contractions. Proposed that some mechanism such as increased production of antiprogesterone reduces the inhibiting effect of progesterone and labour begins  Review table 6.1 The stages of labour  Whole process of childbirth- parturition First-stage labour  Regular contractions of muscles in uterus-->create two changes in the cervix o Effacement (thinning out) and dilation (opening up)  First-stage labour; the beginning of labour, during which there are regular contractions of uterus, and stage lasts until cervix is dilated 8cm (three stages) o Early (contractions spaced far apart 15 to 20 minutes and last about 45 seconds to a minute- fairly easy) o Late (dilation of cervix from 5 to 8 cm, shorter than early stage and contractions are more frequent and intense) o Transition phase (short and difficult, cervix dilates from 8 to 10 cm, pain and exhaustion)  In most respects, first labours are the hardest  12-15 hours for first pregnancy and about 8 hours for later pregnancies Second- stage labour: delivery  Begins when cervix fully dilated and baby starts to move into vagina, or birth canal  Much shorter than the first stage  With each contraction, baby is pushed farther along  Crowning- when the top of the baby becomes visible at the vaginal entrance  Episiotomy; an incision made in the skin just behind the vagina (perineum)  It prevents impaired sexual functioning in later life, reduces the severity of perineal lacerations, and reduces post-delivery pain and medication use  A review found that it didn’t prevent against any of these  Avoid possibility of transmitting gonorrhoea or eye infections to baby, silver nitrate or a similar drug placed in baby's eyes Third stage labour  Placenta detaches from walls of uterus and after birth (placenta and fetal membranes) is expels Caesarean section (C-section)  Prolapses- umbilical cord moves into a position such that it is coming out through cervix ahead of the baby  Rh incompatibility  Placenta previa-placenta is attached to the wall of the uterus or close to the cervix  In C-section- incision made in abdomen through wall of uterus  Lowest rate is in Nunavut, highest rates are in Atlantic provinces and BC.  Rate is higher in Canada than most European counties  Not true that once a women has had C-section, has to always have one  Women who have C-section are 3 times as likely to experience sever illness after the delivery o Reasons: there are more older women giving birth (they many have more difficult labours necessitating C-sections) , fetal monitors are used increasingly (can give early warning), more women are requesting C-section without clear medical reason Childbirth options The lamaze method  Based on the idea that fear and the pain it causes are best eliminated through education 
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