Chapter 4: Pregnancy and Birth

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Chapter 4 Pregnancy and Birth

• Human Growth and Development
• Ashley Roberts and
• Ashley Thornton

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The Prenatal World

• The union of the sperm and egg cells produces a
  Zygote-a single cell from which the baby
  develops.
• Egg is released from the ovary and travels
  through the fallopian tubes into the uterus,
  where it undergoes implantation. This journey
  takes 3-4 days. There are 3 stages of prenatal
  development germinal, embryonic, and fetal.

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The Germinal Period

• First 2 weeks
• Passage through fallopian tube 3-4 days
• Blastocyte-1 week old zygote
• The blastocyte is implanted into the wall of the
  uterus and receives nourishment from the glands
  of the uterus.
• Placenta, umbilical cord, and amniotic sac begin
  to form.

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The Embryonic Period

• 3rd-8th week of development
• Three layers begin to form
• Ectoderm-gives rise to skin, hair, nails, teeth,
  and the nervous system.
• Mesoderm- gives rise to muscles, skeleton,
  circulatory and excretory systems
• Endoderm-gives rise to lungs, liver, and pancreas

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• Heart begins to beat (very rapidly) at 4 weeks.
• 5th week eyes and ears begin to emerge. Body
  limb buds appear.
• 6th 7th week fingers appear on the hands,
  outline of toes is seen, beginning of spinal cord
  is visible.
• After eight weeks, 95 of the body parts are
  formed and general body movements are detected.

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Emergence of the Nervous System

• Begins to emerge at the beginning of the 3rd week
  when the mesoderm sends a chemical signal to the
  ectoderm (neural induction).
• The neural plate begins to form which gives rise
  to the nervous system.
• Neural development occurs quickly
• Neural plate forms
• Neural tube forms-top expands into the brain and
  the bottom becomes the spinal cord

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• Nerve cells begin to form at a rate of 250,000
  cells per minute.
• Nerve cells (neurons) begin to travel to their
  destination from the neural tube to the
  developing brain.
• Connections begin to form (3 trillion)
• Pruning occurs and millions of neurons and
  connections perish.

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The Fetal Period

• Beginning of 3rd month-Birth
• Fetus is growing rapidly in height and weight
• Sex organs appear
• 4th Month 8-10 inches and 6-8 ounces. Mother can
  feel movement. Fetus swallows, digests and
  urinates.

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• 5th Month 10-12 inches and about 1 pound.
• Fetus sleep and wakes just like a newborn.
• 6th Month rapid growth continues
• 7th Month Viability is attained.
• 8th and 9th Month preparing for birth, senses
  function

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Influences on Prenatal Development

• Developmental risk term used to identify those
  children whose well-being is at risk.
• These range from very serious (genetic) to less
  serious (oxygen deprivation)
• The earlier the damage, the greater the chance of
  negative long-term effects.

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Teratogens

• Teratogens are any agents that can cause
  abnormalities.
• They include drugs, chemicals, infections,
  pollutants and mothers physical state.

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Infectious Diseases

• STORCH
• Syphilis STD, can cause fetal fatality
• Toxoplasmosis transmitted by many animals
  especially cats, and occasionally by raw meat.
• Other infections influenza, chicken pox, rare
  viruses
• Rubella German Measles, may cause serous birth
  defects

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• Cytomegalovirus most common. Damage ranges from
  mental retardation to blindness, deafness, and
  even death.
• Herpes Simplex type I is cold sores, type II
  appears in genital area. CNS is particularly
  susceptible

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AIDS

• 20 of newly reported infections are women.
• 7-8 thousand infected with HIV will give birth
  this year.
• 1 in 4 babies born to HIV positive mothers
  develop AIDS.
• Virus can be passed during pregnancy, delivery,
  or while breastfeeding
• Once symptoms appear, babies rarely survive more
  than 5-8 months.

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Chemicals

• Alcohol, cocaine, marijuana, and nicotine can all
  have detrimental affects on a fetus.
• Prescription drugs may also affect a fetus. (i.e.
  thalidomide-caused birth defects)
• DES (diethylstilbestrol) daughters of mothers
  administered this drug were more susceptible to
  cervical cancer.

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Smoking and Alcohol

• Smoking affects everything about the reproduction
  process. It results in a smaller than normal
  fetus, breathing difficulties and low resistance
  to infection.
• Women who consume alcohol daily can damage their
  babies. Fetal Alcohol Syndrome produces physical
  abnormalities, growth deficiency, CNS dysfunction.

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Maternal Influences

• Nutrition- adequate food supply, protection
  against stress
• Weight gain of about 15-25lbs is healthy.
• Supplements may provide additional protein, iron,
  calcium, fiber, folic acid, and vitamins.

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Emotions

• 1ST trimester mother is focused on personal well
  being, 2nd her concern turns to the baby, 3rd she
  develops a sense of oneness with the child.
• Adjust family relationships so the child will
  receive unconditional acceptance.
• Woman and unborn child develop a bond.
• Learning to give of oneself.

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Diagnosing Fetal Problems

• Amniocentesis-provides information about sex and
  70 chromosomal abnormalities
• Alpha- Fetoprotein Test-genetic diagnosis, and
  fetal blood transfusion
• Chorionic Villi Sampling-to determine genetic
  structure
• Ultrasound

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The Birth Process

• A woman usually becomes aware of the beginning of
  labor in 1 of 3 ways
• Passage of blood from the vagina
• Passage of amniotic fluid
• Uterine contractions and discomfort

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• Labor Proceeds in 3 stages
• Dilation cervix dilates to about four inches.
  Dilation is responsible for the labor pains and
  may last for hours.
• Expulsion fetus is driven through the birth
  canal
• The Afterbirth placenta and other membranes are
  discharged.

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• Complications may occur
• Forceps delivery- due to extreme fatigue,
  inadequate contraction strength, and cardiac
  problems.
• Breech Birth fetus is not in head down position
• Cesarean Section child can not come through
  birth canal
• Anoxia lack of oxygen
• The Rh factor- incompatibility of blood types
  between mother and child.

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Prematurity

• Average duration of pregnancy is 280 days. Many
  babies are born pre-term preemies
• Borderline-born between 37 and 38 weeks
• Moderate- born between 31 and 36 weeks.
  Classified and low birth weight babies.
• Extreme- born between 24 and 30 weeks. Classified
  as very low birth weight babies. Account for 84
  of neonatal deaths.

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Prematurity may be caused by

• Low socioeconomic status
• Smoking
• Alcohol
• Cervical problems, high blood pressure, unusual
  stress, diabetes, and heart disease.