Chapter 12 Conception, Pregnancy, and Childbirth

The Fertilization Process Ovum released from ovary, drifts to fallopian tube –Oocyte viable ~ hours after ovulation –Sperm viable ~ 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 6 th or 7 th day Blastocyst becomes embryo after implantation in uterus Embryo is called a fetus after 8 th 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