Transcript Conception, Pregnancy, and Childbirth

Conception, Pregnancy,
and Childbirth
Chapter 11
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Copyright 2008 Allyn & Bacon
Conception, Pregnancy, and
Childbirth
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Conception: Against All Odds
Infertility and Assisted Reproductive
Technology
Pregnancy
Prenatal Development
Childbirth
The Postpartum Period
Copyright 2008 Allyn & Bacon
Conception: Against All Odds
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Conception
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Union of a sperm cell and an ovum
Zygote: A fertilized ovum
 Each ejaculate contains an average of 200 to 400
million sperm.
 Ovum secretes a chemical that attracts sperm.
 Fertilization normally occurs in a fallopian tube.
 Ovum is surrounded by zona pellucida which must
be penetrated by sperm to fertilize it.
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Sperm secrete the enzyme hyaluronidase, which briefly
thins zona pellucida, enabling penetration.
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Conception: Against All Odds
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Ova carry X sex chromosomes
Sperm carry either X or Y sex chromosomes
Girls are produced from union of 2 X
Boys are produced from union of an X and a Y
Y sperm appear to be faster swimmers
Male fetuses more likely lost in spontaneous
abortion, which helps balance the sexes
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Spontaneous abortion: loss of pregnancy, often in the
first month, and sometimes before the woman knows
she’s pregnant
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Conception: Against All Odds
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Optimizing the Changes of Conception
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Ovum can be fertilized for 4-20 hours after ovulation
Sperm are most active within 48 hours after ejaculation
Ways to predict ovulation
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Basal body temperature (BBT) chart
Analyzing urine or saliva for luteinizing hormone
Tracking vaginal mucus
Additional considerations
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Coitus in the male-superior position
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Conception: Against All Odds
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Selecting the Sex of Your Child(?)
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Reasons to select:
Personal preference
 Family balancing
 Avoidance of sex-linked diseases
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Folklore provides many techniques
Selective abortion
Infanticide
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Conception: Against All Odds
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Selecting the Sex of Your Child(?)
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Sperm-separation procedures
Preimplantation genetic diagnosis (PGD)
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Is currently the most reliable sex-selection method
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Infertility and Alternative Ways
of Becoming Parents
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Infertility
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Inability to conceive a child
Term usually not applied until the failure has
persisted for more than a year
 Women over the age of 35 are advised to seek help
after 6 months of trying
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About 15% of American couples experience
infertility.
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Infertility and Alternative Ways
of Becoming Parents
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Male Fertility Problems
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Causes include:
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Low sperm count
Irregularly shaped sperm
Low sperm motility (self-propulsion)
Chronic diseases (diabetes, infectious diseases)
Injury to the testes
Autoimmune response (antibodies deactivate sperm
Pituitary imbalance and/or thyroid disease
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Infertility and Alternative Ways
of Becoming Parents
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Male infertility solutions include:
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Microsurgery
Artificial insemination
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Introduction of sperm into the reproductive tract
through means other than sexual intercourse
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Infertility and Alternative Ways
of Becoming Parents
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Female Fertility Problems
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Causes include:
Irregular ovulation, including failure to ovulate
 Obstructions or malfunctions of the reproductive
tract, such as blocked fallopian tubes
 Endometriosis
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Endometrial tissue is sloughed off into the abdominal
cavity rather than out of the body during menstruation
Declining hormone levels
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Infertility and Alternative Ways
of Becoming Parents
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Female infertility solutions include:
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Fertility drugs
Laparoscopy (for detection & treatment)
In vitro fertilization (IVF)
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Gamete intrafallopian transfer (GIFT)
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Mature ova are surgically removed from an ovary and placed
in a laboratory dish along with sperm
Sperm and ova are inserted into a fallopian tube to
encourage conception
Zygote intrafallopian transfer (ZIFT)
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Ovum is fertilized in a laboratory dish and then placed in a
fallopian tube
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Infertility and Alternative Ways
of Becoming Parents
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Female infertility solutions include:
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Donor IVF
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Embryonic transfer
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Ovum is taken from one woman, fertilized, and then injected
into the uterus or fallopian tube of another woman
Woman volunteer is artificially inseminated by the male
partner of the intended mother
Embryo is removed and inserted within the uterus of the
intended mother
Intracytoplasmic sperm injection
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Single sperm is injected directly into an ovum
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Infertility and Alternative Ways
of Becoming Parents
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Female infertility solutions include:
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Surrogate motherhood
Woman is impregnated through artificial
insemination, with the sperm of a prospective
father
 Carries the embryo and fetus to term
 Gives the child to the prospective parents
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Adoption
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Pregnancy
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Early Signs of Pregnancy
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Missing a period
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It is not a reliable indicator.
Basal body temperature remains high for
about three weeks after ovulation
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Pregnancy
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Pregnancy Tests
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Human chorionic gonadotropin (HCG)
Hormone produced by women shortly after
conception
 Detected in urine as early as third week of
pregnancy
 Detected in a blood test as early as the eighth day of
pregnancy
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Pregnancy
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Early Effects of Pregnancy
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Tenderness of the breasts
Morning sickness
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Symptoms of pregnancy including nausea, aversions to
specific foods, and vomiting
May occur throughout the day
Usually subsides by about the twelfth week of pregnancy
May experience more fatigue and frequent urination
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Pregnancy
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Miscarriage
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Spontaneous abortion; causes include chromosomal
defects in the embryo or fetus
More common in older pregnant women
Sex During Pregnancy
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Given a normal pregnancy, coitus is safe throughout
pregnancy until the start of labor.
A pregnant woman’s interest in sex may vary.
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Tends to be higher during the second trimester compared to
the first and third
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Pregnancy
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Psychological Changes During Pregnancy
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Reflect desire to be pregnant, her physical
changes, and her attitudes toward these
changes
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May also depend on the trimester of pregnancy
Sympathetic pregnancy
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Experiencing of a number of signs of pregnancy
by the father
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Prenatal Development
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Delivery date may be calculated using
Nagele’s rule
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First day of the last menstrual period
Add 7 days
Subtract 3 months
Add 1 year
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Prenatal Development
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Stages of Prenatal Development
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Germinal stage
First two weeks of pregnancy
 Period before implantation in the uterus
 Also called the period of the ovum
 Blastocyst
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Embryo is a sphere of cells surrounding a cavity of fluid
Embryonic disk: Platelike inner part of the blastocyst, which
differentiates into the ectoderm, mesoderm, and endoderm of
the embryo
Trophoblast: Outer part of the blastocyst, from which the
amniotic sac, placenta, and umbilical cord develop
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Prenatal Development
Early Days
of the
Germinal
Stage
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Prenatal Development
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IF THERE IS A PICTURE OF A ZYGOTE
IN THE GERMINAL STATE, PLEASE
INSERT IT HERE.
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Prenatal Development
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Embryonic stage
Lasts from implantation through the eighth week
 Differentiation of the major organ systems occurs
 Development of the embryo follows two trends
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Cephalocaudal: from the head downward
Proximodistal: from the central axis of the body outward
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Prenatal Development
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Ectoderm
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Endoderm
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Outermost cell layer of the embryo, from which skin and
nervous system develop
 Neural tube: A hollow area in the blastocyst from
which the nervous system will develop
Inner layer of the embryo, from which the lungs and
digestive system will develop
Mesoderm
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Central layer of the embryo, from which the bones and
muscles develop
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Prenatal Development
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Amniotic sac
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The sac containing the embryo and, later, the fetus
Amniotic fluid
 Suspends and protects the fetus
Placenta
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Organ connected to fetus by umbilical cord and serves
as relay station between mother and embryo (or fetus),
allowing the exchange of nutrients and wastes
Secretes hormones that preserve pregnancy, stimulate
uterine contractions that induce childbirth, and help
prepare breasts for breastfeeding
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Prenatal Development
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IF THERE IS A PICTURE OF AN
EMBRYO, PLEASE INCLUDE IT HERE.
THE FIRST 2 PICTURES OF THE
FIGURE ON PAGE 330 WOULD WORK
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Prenatal Development
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Fetal stage
Begins by the ninth week and continues until birth
 Fetal movements can be felt
 Age of viability: The age at which a fetus can sustain
independent life
 During the seventh month, fetus typically turns
upside down in the uterus
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Cephalic presentation
 Emergence of the baby head first from the womb
If not, the fetus, if born prematurely, may be in a breech
presentation
 Emergence of the baby feet first from the womb
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Prenatal Development
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IF THERE IS A PICTURE OF A FETUS,
PLEASE INSERT IT HERE. THE THIRD
PICTURE ON PAGE 330 WOULD
WORK.
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Prenatal Development
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Environmental Influences on Prenatal
Development
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Mother’s diet
Malnutrition
 Obesity
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Maternal diseases and disorders
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Teratogens
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Environmental influences or agents that can damage an
embryo or fetus
Critical periods of vulnerability
 When embryo or fetus is vulnerable to the effects of a
teratogen
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Prenatal Development
Critical Periods
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Prenatal Development
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Rubella (German measles)
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Viral infection that can cause mental retardation
and heart disease in an embryo
Syphilis
Sexually transmitted disease caused by a bacterial
infection
 May cause miscarriage or stillbirth or be passed
along to the child in the form of congenital
syphilis
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Prenatal Development
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HIV/Acquired immunodeficiency syndrome
(AIDS)
Destroys white blood cells in the immune system
 Majority of babies born to infected mothers do not
become infected themselves
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Toxemia
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Life-threatening condition characterized by high
blood pressure
Ectopic pregnancy
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Fertilized ovum becomes implanted someplace other
than the uterus
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Prenatal Development
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Rh incompatibility
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Antibodies produced by a pregnant woman are
transmitted to the fetus and may cause brain
damage or death
Drugs taken by the mother (and the father)
OTC
 Prescription
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Hormones
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Diethylstilbestrol (DES)
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An estrogen that was once given to women at risk for
miscarriage to help maintain pregnancy
Suspected of causing cervical and testicular cancer in
some children
whose mothers used it when pregnant
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Prenatal Development
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Vitamins (high doses)
Narcotics
Tranquilizers and sedatives
Marijuana
Alcohol
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Cigarette smoking
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Fetal alcohol syndrome (FAS)
Increases risk of low birthweight, early infant mortality, and
intellectual impairments
Other agents, for example X-rays
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Prenatal Development
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Chromosomal and Genetic Abnormalities
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Down syndrome
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Sickle-cell anemia
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More common among certain racial and ethnic groups
Causes sickle-shaped red blood cells that can form clumps
Tay-Sachs disease
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Usually caused by an extra chromosome on the 21st pair
Obvious physical characteristics
Risk increases with maternal age
Fatal neurological disease
Sex-linked genetic abnormalities
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Recessive trait: expressed if paired with other recessive genes
More likely to affect sons of female carriers
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Prenatal Development
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Averting chromosomal and genetic abnormalities
Genetic counseling
 Amniocentesis, usually performed at four months and
chorionic villus sampling, usually performed at 10
weeks
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Tests detect Down syndrome, sickle-cell anemia, Tay-Sachs
disease, spina bifida, muscular dystrophy, Rh incompatibility,
and other conditions, as well as identify the sex of the fetus.
Ultrasound
 Parental blood tests
 Test of fetal DNA
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Childbirth
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Childbirth
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Lightening
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Braxton-Hicks contractions
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So-called false labor contractions that are relatively painless
Prostaglandins
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Baby’s head drops into the pelvis, usually early in 9th month
Uterine hormones that stimulate uterine contractions
Oxytocin
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Pituitary hormone that stimulates uterine contractions
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Childbirth
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Stages of Childbirth
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First stage
Uterine contractions efface and dilate the cervix
 Transition
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Process during which the cervix becomes nearly fully
dilated and the head of the fetus begins to move into the
birth canal
May last from a couple of hours to more than a
day during a first pregnancy and is usually shorter
in subsequent births
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Childbirth
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Second stage
Shorter than first stage
 Begins when cervix is fully dilated and baby begins to
move into the vagina
 Episiotomy may be performed
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Third stage
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Surgical incision in the perineum that widens the birth canal,
preventing random tearing during childbirth
Placenta is expelled
In the new world
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Once baby is Copyright
breathing
adequately umbilical cord is cut
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Childbirth
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INSERT FIGURE 11.6 HERE
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Childbirth
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Methods of Childbirth
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Anesthetized childbirth
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General anesthesia
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The use of drugs to put people to sleep and eliminate pain
May prolong labor
They cross placental barrier and lower newborn’s
responsiveness
Local anesthesia
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Eliminates pain in a specific area of the body
Decreases newborn’s responsiveness
Little evidence that medicated childbirth has serious,
long-term consequences
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Childbirth
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Prepared childbirth: Lamaze method
Women are taught to reduce pain by thinking of
pleasant images or engaging in breathing and
relaxation exercises.
 Women attend classes and have a “coach” to help
them through the birthing process.
 Anesthetics can be used, if needed.
 Gives women a sense of control over delivery
process
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Copyright 2008 Allyn & Bacon
Childbirth
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Cesarean section
Fetus is delivered through a surgical incision in the
abdomen
 May cause urinary tract infections, inflammation of
the uterine wall, blood clots, or hemorrhaging
 Increases rate of pregnancy-related death
 Advised when normal delivery is difficult or is
threatening the health or life of mother or child
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Baby is in breech (feet downward) or transverse position
(crosswise birth position), large, mother is infected with
HIV or herpes, mother is tired
Today, about 24% of births is by C-section.
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Some view this number as too high
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Childbirth
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Birth Problems
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Anoxia: Oxygen deprivation
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Can result in brain damage and mental retardation
If prolonged, can result in cerebral palsy and death
Occurs due to constriction of the umbilical cord
Preterm and low-birthweight children
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Born before 37 weeks of gestation
A weight of less than 5 pounds
Respiratory distress syndrome: Cluster of breathing
problems, responsible for many neonatal deaths
Usually require monitoring and extra care
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Childbirth
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Stillbirth
Baby is born dead
 Connected to fetal abnormalities, infection,
maternal medical conditions, and pregnancy
complications
 Most cases have no clear cause
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The Postpartum Period
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Postpartum: Following Birth
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Maternal Depression
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Baby blues
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Last for about ten days and do not impair functioning
Postpartum depression
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Persistent and severe mood changes during the
postpartum period, involving feelings of despair and
apathy and characterized by changes in appetite and
sleep, low self-esteem, and difficulty concentrating
Affects 1 in 5 to 10 women
May last for weeks or months
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The Postpartum Period
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Breastfeeding Versus Bottle-Feeding
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About three in five women in the U.S. breastfeed
It is recommended that women breastfeed for a year or
more
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Prolactin
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It reduces the general risk of infections and allergies.
A pituitary hormone that stimulates milk production
Lactation
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Production of milk by the mammary glands
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The Postpartum Period
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Resumption of Ovulation and Menstruation
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Lochia
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Reddish vaginal discharge that may persist for a month after
delivery
A nonnursing mother does not resume menstruation
until 2 to 3 months postpartum.
Ovulation typically precedes menstruation.
Resumption of Sexual Activity
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Obstetricians usually advise a 6-week waiting period.
Copyright 2008 Allyn & Bacon