Chapter 12

Conception, Pregnancy, and Childbirth

The Fertilization Process

• Ovum released from ovary, drifts to fallopian tube– Oocyte viable ~ 12 - 24 hours after

ovulation– Sperm viable ~ 12 - 48 hours

• Capacitation: takes 6-8 hours– biochemical changes in sperm cell; release

enzymes that allows it to penetrate egg’s outer membranes

Fertilization Process

• A single sperm is inside the oocyte cytoplasm– An electrical reaction prevents any other sperm

from entering

• Oocyte swells– Detaches sperm that cling to outer layer

• Sperm and ovum nuclei release chromosomes– Chromosomes divide to form the diploid zygote

containing 23 pairs of chromosomes– Fertilization is now complete

Development of the Conceptus

• Zygote undergoes cell divisions– Becomes a blastocyst of 100 cells after 4-

5 days– Blastocyst implants in uterine lining on 6th

or 7th day

• Blastocyst becomes embryo after implantation in uterus

• Embryo is called a fetus after 8th week

Pregnancy Detection

– Test for human chorionic gonadotropin (HCG)

– Blood analysis– Home pregnancy tests– Early physical signs

• Changes in cervix occur about 4 weeks after a missed period

• Hegar’s sign• Labia change color, gaining purple hue

Changes in Women During Pregnancy

• Vary according to woman’s personality, feelings, and circumstances– Changes in relationships– Physical and emotional changes during

each trimester• Three trimesters—each 3 months long• First trimester may include nausea, vomiting,

fatigue

Complications of Pregnancy and Dangers to the Fetus

• Effects of teratogens– Substances that cause defects in

embryonic and fetal development

• Infectious diseases– German Measles (rubella)– Group B streptococcus

Complications of Pregnancy and Dangers to the Fetus

• Sexually transmitted infections

• Can be transmitted from pregnant woman to fetus, newborn, or infant

• Chlamydia• Gonorrhea• Hepatitis B• HIV• Syphilis• Genital herpes

Complications of Pregnancy and Dangers to the Fetus

• Pregnancy after age 35– Is more common as women wait to have

children– Increased likelihood of chromosomal

variation– Risk increases with increasing maternal

age

Complications in Pregnancy

• Ectopic pregnancy

• Pregnancy-induced hypertension

• Premature births

• Delayed labor

Diagnosing Abnormalities of the Fetus

• Ultrasound

• Amniocentesis

• Chorionic villus sampling (CVS)

• Alpha-fetoprotein (AFP) screening

Ultrasound

• High frequency sound waves determine size and position of fetus

• Sonogram—picture

• Estimates fetal age, guides during amniocentesis, checks for physical birth defects, evaluates complications during pregnancy

Amniocentesis

• Amniotic fluid is withdrawn with needle inserted through abdominal wall

• Detects: fetal abnormalities; Down’s syndrome, Turner’s syndrome, cystic fibrosis, spina bifida, sex and age

• 0.5-2% chance of fetal death

Chorionic Villus Sampling (CVS)

• Thin catheter inserted through abdomen or cervix into uterus and some chorionic villi are sucked into tube

• Detects: fetal abnormalities

• Performed 9-11 weeks

Alpha-fetoprotein Screening

• Test run on mother’s blood

• After 16 weeks of pregnancy

• Detects: defects of spine, spinal cord, skull and brain

Pregnancy Loss

• Early pregnancy loss

• Miscarriage

• Infant mortality

• Coping with loss

Infertility

• The inability to conceive a child after a year of unprotected intercourse or the inability to carry a child to term

• Fertility issues are equally distributed among men and women

• 1% of children in U.S. are the product of assisted fertility

Female Infertility

• Physical causes– Pelvic Inflammatory Disease, an infection of

the fallopian tubes or uterus– Approximately 20%

• Hormonal & psychological causes– Hormone release may be atypical– Stress, anxiety, allergy– Approximately 20%

• Environmental factors

Male Infertility

• Low sperm count• Decrease of sperm motility• Misshapen sperm• Sperm duct blockage• Ejaculatory difficulties• Environmental factors• Men’s fertility begins dwindling after age 27

Infertility Treatment

• Enhancing fertility– Selective timing of sexual activity– Man wears boxer underwear– Woman lies with her back elevated

following internal ejaculation

Medical Intervention

• Fertility medications

• Surgery

• Artificial insemination

Assisted Reproductive Technology

• In vitro fertilization - IVF

• Gamete intrafallopian transfer – GIFT

• Zygote intrafallopian transfer – ZIFT

• Surrogate motherhood

• Cloning

• Sex selection

Giving Birth: Labor and Delivery

• Relaxin released by the placenta

• Braxton Hick contractions

Labor Stages

• Stage 1:– Effacement: thinning of cervix– Dilation: opening up of cervix– Mucus plug is expelled– Amniotic sac ruptures– Contractions are regular and progressive– Transition

Labor and Delivery

• Stage 2– Begins when baby’s head moves into birth

canal– Ends when baby is born– Vernix: waxy substance which may cover

baby

• Stage 3– Afterbirth: placenta is expelled

Following birth

• Neonate

• Apgar score

• Lochia

• Joy

Choices in Childbirth

• Hospital birth

• Cesarean section

• Prepared childbirth

• Episiotomy

• Birthing rooms and centers

• Home birth

• Midwifery

Breast Feeding

• Colostrum

• Benefits– Bonding– Immune system of baby– HIV

Becoming a Parent

• Postpartum period

• Postpartum depression

• Postpartum psychosis

• Family Medical Leave Act

Summary

• Fertilization and fetal development

• Being pregnant

• Infertility

• Giving birth

• Becoming a parent