CONCEPTION, PREGNANCY, AND CHILDBIRTH

Chapter 11

Learning Objectives• Conception• Infertility• Pregnancy• Prenatal Development• Childbirth• The Postpartum Period

Conception

• Zygote is 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• Sperm secrete the enzyme hyaluronidase,

which briefly thins zona pellucida, enabling penetration

Union of a sperm cell and an ovum

Conception

• 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• Spontaneous abortion is the loss of pregnancy,

often in the first month, and sometimes before the woman knows she’s pregnant

Union of a sperm cell and an ovum

Conception

• Ovum can be fertilized for 4-20 hours after ovulation

• Sperm are most active within 48 hours after ejaculation

• Ways to predict ovulation• Basal body temperature (BBT) chart• Analyzing urine or saliva for luteinizing

hormone• Tracking vaginal mucus

• Coitus in the male-superior position

Optimizing Chances

Conception

• Reasons to select• Personal preference• Family balancing• Avoidance of sex-linked diseases

• Folklore provides many techniques• Selective abortion• Infanticide• Sperm-separation procedures• Pre-implantation genetic diagnosis (PGD)

• Currently the most reliable sex-selection method

Selecting the Sex of Your Child

Critical Thinking

Sex selection raises many moral and ethical questions. Many people wonder whether people have the “right” to select the sex of their children.

Where do you stand on the issue? Why?

Infertility

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

• About 15% of American couples experience infertility.

Infertility

Male Fertility Problems

• 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

Infertility

Male infertility solutions include

• Microsurgery• Artificial insemination• Introduction of sperm into

the reproductive tract through means other than sexual intercourse

Infertility

Female Fertility

Problems

• Irregular ovulation, including failure to ovulate (10-15%)

• Obstructions or malfunctions of the reproductive tract, such as blocked fallopian tubes

• Endometriosis• Endometrial tissue is sloughed

off into the abdominal cavity rather than out of the body during menstruation

• Declining hormone levels

Infertility

Female infertility solutions include

• Fertility drugs• Laparoscopy (for detection & treatment)• In vitro fertilization (IVF)

• Mature ova are surgically removed from an ovary and placed in a laboratory dish along with sperm

• Gamete intrafallopian transfer (GIFT)• Sperm and ova are inserted into a

fallopian tube to encourage conception

• Zygote intrafallopian transfer (ZIFT)• Ovum is fertilized in a laboratory dish

and then placed in a fallopian tube

Infertility

Female infertility

solutions include

• Donor IVF• Ovum is taken from one woman,

fertilized, and then injected into the uterus or fallopian tube of another woman

• Embryonic transfer• 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• Single sperm is injected directly into an

ovum

Infertility

Female infertility solutions include

• 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

• Adoption

Pregnancy

Early Signs of Pregnancy

• Missing a period• It is not a reliable indicator.

• Basal body temperature remains high for about three weeks after ovulation

Pregnancy

Early Effects of Pregnancy

• Tenderness of the breasts• Morning sickness• 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

Pregnancy

Miscarriage

• Spontaneous abortion• Causes include chromosomal defects in the embryo or fetus

• More common in older pregnant women

Pregnancy

Sex During Pregnancy

• Given a normal pregnancy, coitus is safe throughout pregnancy until the start of labor

• A pregnant woman’s interest in sex may vary • Tends to be higher during the second

trimester compared to the first and third

Pregnancy

Psychological Changes During Pregnancy

• Reflect desire to be pregnant, her physical changes, and her attitudes toward these changes• May also depend on the trimester of

pregnancy• Men, like women, respond differently to

pregnancy

Prenatal Development

Calculate delivery date by using Naegele’s rule

Use date of first day of the last menstrual period

Add 7 days

Subtract 3 months

Add 1 year

Prenatal Development

Figure 11.3. The ovarian cycle, conception, and the early days of the germinal stage (p. 306).

Stages of Prenatal DevelopmentGerminal stage

First two weeks of pregnancy

Period before implantation in the uterus

Also called the period of the ovum

Blastocyst Embryo is a sphere of cells surrounding a cavity of fluid

Embryonic disk is a platelike inner part of the blastocyst

Differentiates into the ectoderm, mesoderm, and endoderm of the embryo

Trophoblast is the outer part of the blastocyst

Develops into the amniotic sac, placenta, and umbilical cord

Stages of Prenatal DevelopmentEmbryonic stage

Lasts from implantation through the eighth week

Differentiation of the major organ systems occurs

Development of the embryo follows two trends

Cephalocaudal – from the head downward

Proximodistal – from the central axis of the body outward

Stages of Prenatal DevelopmentEctoderm• Outermost cell

layer of the embryo from which skin and nervous system develop• Neural tube –

hollow area in the blastocyst from which the nervous system will develop

Endoderm• Inner layer

of the embryo from which the lungs and digestive system will develop

Mesoderm• Central

layer of the embryo from which the bones and muscles develop

Stages of Prenatal DevelopmentAmniotic sac• The sac containing

the embryo/fetus• Amniotic fluid

• Suspends and protects the embryo/fetus

Placenta• Organ connected to

fetus by umbilical cord • Relay station between

mother and embryo/ fetus; allows for the exchange of nutrients and wastes

• Secretes hormones that • preserve pregnancy• stimulate uterine

contractions that induce childbirth

• help prepare breasts for breastfeeding

Stages of Prenatal Development

Figure 11.4. Human embryos and fetuses (p. 307).

Stages of Prenatal DevelopmentFetal stage

Begins by the ninth week and continues until birth

Fetal movements can be felt

Age of viability is the age at which a fetus can sustain independent life

During the seventh month, the fetus typically turns upside down in the uterus

Cephalic presentation

Emergence of the baby head first from the womb

If not, may be in a breech presentation

Can complicate premature birth

Environmental Influences on Prenatal Development

• Malnutrition• Obesity

Mother’s diet

• Teratogens • 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

Maternal diseases and

disorders

Environmental Influences on Prenatal Development

Figure 11.5. Critical periods (p. 310).

Prenatal Development

Rubella (German measles)• 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

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

Toxemia• Life-threatening

condition characterized by high blood pressure

Ectopic pregnancy• Fertilized ovum

becomes implanted someplace other than the uterus

Prenatal DevelopmentRh incompatibility• 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

Hormones• Diethylstilbestrol (DES)

• 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

Vitamins (high doses) Narcotics Tranquilizers

and sedatives MarijuanaAlcohol• Fetal

alcohol syndrome (FAS)Cigarette smoking

• Increases risk of low birth weight, early infant mortality, and intellectual impairments

X-rays

Prenatal Development

• Genetic counseling• Chorionic villus

sampling (10 weeks)

• Amniocentesis (4 months)

• Ultrasound• Parental blood tests• Test of fetal DNA

Averting chromosom

al and genetic

abnormalities

Childbirth

Lightening

Baby’s head drops

into the pelvis, usually

early in 9th month

Braxton-Hicks contractions

So-called false labor contractions that are relatively painless

Prostaglandins

Uterine hormones

that stimulate uterine

contractions

Oxytocin

Pituitary hormone

that stimulates

uterine contraction

s

Stages of Childbirth

First stage

• Uterine contractions efface and dilate the cervix• 4 inches (10 cm)

• Transition• 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

Stages of Childbirth

Second stage

• Shorter than first stage• Begins when cervix is fully dilated and

baby begins to move into the vagina• Episiotomy may be performed

• Surgical incision in the perineum that widens the birth canal, preventing random tearing during childbirth

• Ends with birth of baby

Stages of Childbirth

Third stage• Placenta is expelled

In the new world

• Once baby is breathing adequately umbilical cord is cut

Stages of Childbirth

Figure 11.7. The stages of childbirth (p. 319).

Methods of Childbirth

Anesthetized childbirth

• General anesthesia• 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

• Eliminates pain in a specific area of the body• Decreases newborn’s responsiveness• Little evidence that medicated childbirth has serious, long-

term consequences Figure 11.7. The stages of childbirth (p. 319).

Methods of Childbirth

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 Figure 11.7. The stages of childbirth (p. 319).

Methods of Childbirth

Cesarean section• Fetus is delivered through a surgical incision in the abdomen• Mostly without complications• May cause urinary tract infections, inflammation of the uterine wall,

blood clots, or hemorrhaging• Increases rate of pregnancy-related death (4x)• Advised when normal delivery is difficult or is threatening the health or

life of mother or child• 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 29% of births are by C-section.• Some view this number as too high

• Can deliver subsequent babies vaginallyFigure 11.7. The stages of childbirth (p. 319).

Birth Problems

Anoxia: Oxygen deprivation

• 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-birth weight

children

• 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

Stillbirth

• Baby is born dead• Connected to fetal abnormalities, infection,

maternal medical conditions, and pregnancy complications

• Most cases have no clear cause

Postpartum Period

Maternal Depression• Baby Blues

• Statistically normal• Lasts for about 10 days and does not impair functioning

Postpartum Period

Maternal Depression• Postpartum Depression

• Affects 1 in 5 to 10 women• 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

• May result from interaction of biological and psychological factors• Begins 4 weeks post delivery and may linger for weeks or months

Postpartum Period

Breastfeeding vs. Bottle-

Feeding

• About three in five women in the U.S. breastfeed

• It is recommended that women breastfeed for a year or more• It reduces the general risk of infections

and allergies• Prolactin

• A pituitary hormone that stimulates milk production

• Lactation• Production of milk by the mammary

glands

Postpartum Period

Resumption of Ovulation and Menstruation

• Lochia• Reddish vaginal discharge that may

persist for a month after delivery• A non-nursing mother does not resume

menstruation until 2 to 3 months postpartum

• Ovulation typically precedes menstruation

Resumption of Sexual Activity

• Obstetricians usually advise a 6-week waiting period