1. Human Fetal Development

2. Female Reproductive Organs

3. Conception Every 28 days, an ovum, lasts 24 hours
Millions of sperm, viable for up to 6 days
Conception in the fallopian tube
Tubal pregnancy
Conceptions most likely: on day of ovulation or the two days preceding ovulation

4. Conception Chromosomes join & form zygote
Sperm attaches & penetrates ovum

5. Progress Before Birth: Prenatal Development
3 phases
germinal stage = first 2 weeks
conception, implantation, formation of placenta
embryonic stage = 2 weeks – 2 months
Period of rapid growth and differentiation, organogenesis
formation of vital organs and systems
fetal stage = 2 months – birth
bodily growth continues, movement capability begins, brain cells multiply
age of viability
Prenatal development begins with the germinal stage, lasting from conception to about 2 weeks. During this stage, rapid cell division occurs, and the mass of cells migrates to the uterus and beings to implant into the uterine wall, forming a placenta during the implantation process.
The placenta is a structure that allows oxygen and nutrients to pass into the fetus from the mother’s bloodstream and bodily wastes to pass out to the mother.
The embryonic stage lasts from 2 weeks to 2 months and is the period when most of the vital organs and bodily systems such as the heart, spine, and brain emerge. The embryonic period is a time of great vulnerability; if anything interferes with development during this time period, effects can be devastating.
The fetal period lasts from 2 months to birth. During the early parts of this stage, the muscles and bones begin to form. The body continues to grow and function, with sex organs developing in the 3rd month and brain cells multiplying during the final 3 months.
Somewhere between 22 and 26 weeks, the age of viability is reached…when the baby could survive if born prematurely. At 22 or 23 weeks, chances for survival are slim, but by weeks chances improve to a survival rate of about 85%.

6. Gametes and Zygote Sperm Sperm Ovum Gametes (reproductive cells)
Fertilization
Zygote

7. The Period of the Zygote or the Germinal Stage
First Two weeks following conception
From fallopian tubes to attachment to the uterine wall
Blastocyst, cells, 4th day
Embryonic disk (organism)
Outer Ring (umbilical cord & placenta)
Implantation between days 7 & 9

9. Blastocyst has an outer layer of cells called the trophoblast, an inner cell mass, and a fluid filled cavity called the blastocele.
The trophoblast and part of the inner cell mass will form the membranes of the fetal portion of the placenta, the rest of the inner mass forms the embryo.
Blastocele
Trophoblast
Blastocyst

10. Zygote Period Continued
Amnion Membrane, amniotic fluid
Yolk sack produces blood cells
Chorion Membrane
Placenta - Food, oxygen, waste
Umbilical cord
30% of zygotes do NOT survive

11. The Period of the Embryo
5.5 Weeks
9 Weeks
From 2nd week through 2nd month
Very rapid prenatal development
Embryonic disk folds into three layers
Ectoderm - Nervous system (fast develop.) & skin
Mesoderm - skeleton, muscles, circulation
Endoderm - Digestion, lungs, urinary tract

14. Endodermal Differentiation

15. Embryonic Period Cont. Many body parts develop the 2nd month
Fingers, toes, facial features, nervous system cells fire, teeth buds have formed
Embryo’s posture becomes upright
The embryo can move
The embryo responds to touch (mouth & feet)

16. 11 Week Fetus

17. The Period of the Fetus Growth and finishing Third month
Organs, muscles & nervous system organize and connect
External genitals – visible with ultrasound
End of first trimester

18. Second Trimester 13-24 weeks - first movement felt
Vernix covers fetus, prevents chapping
Lanugo hold vernix to skin
Trillions of brain neurons produced
Stimulated by sound and light

19. Third Trimester Age of viability - 22 to 26 weeks
Cerebral cortex enlarges
Responsive to external stimulation
Fat layer develops for temp. reg.
Moves to the upside-down position
Fetus moves less

20. Ready for birth.

21. Figure 11.1 Overview of fetal development

22. What can go wrong? Two basic kinds of problems:
Genetic: Improper cell division: e.g., Trisomy 21 Gene defects: Single gene defects Recessive gene defects
Environmental: teratogens Teratogen = monster maker Any environmental agent that produces birth defects

24. Influence of Teratogens
Larger doses, over time, more negative
Genetics can help or hinder teratogens
Several negative factors increase impact
Sensitive periods especially important
Embryonic period most susceptible
Physical and psychological effects

25. Drugs Thalidomide – sedative - 1960’s
Aspirin - low birth weight, infant death Poor motor develop., lower IQ
Heavy caffeine use - miscarriage Premature births, irritability

26. Illegal Drugs Cocaine, heroin, methadone
Prematurity, low birth weight
Physical defects, breathing problems,
Drug addiction & death
Cocaine - lasting difficulties
Genital, urinary tract, kidney, heart deformities
Brain seizures

27. Crack babies Lowest birth weight Central nervous system damage
Fathers on cocaine may pass it on
Multiple harmful effects of more than one drug

28. Tobacco use Low birth weight and premature births Impaired breathing
Miscarriage & infant death
Placenta doesn’t work correctly
Greater concentration of carbon monoxide
Passive smoking also injurious

29. Alcohol Fetal alcohol syndrome (FAS)
Large amounts of alcohol, whole pregnancy
Mental retardation
Slow physical growth
Facial abnormalities
Alcohol interferes with cell duplication
Especially neural cells
Draws oxygen away from organism

30. Fetal Alcohol Syndrome

31. Hormones Diethylstilbestrol (DES), 1945-70 Vaginal cancer
Malformation of the uterus
Miscarriage, low birth weight
In males, genital abnormalities, cancer

32. Radiation Hiroshima & Nagasaki X-Rays - avoid during pregnancy
Miscarriage, slow physical growth
Underdeveloped brains
Malformation of skeleton & eyes
X-Rays - avoid during pregnancy

33. Environmental Pollutants
100,000 in common use
Mercury
Mental retardation, speech problems
Difficulty chewing & swallowing
Uncoordinated movements
Polychlorinated Biphenyl (PCB)
Lower birth weight, smaller heads
Poor memory, lower verbal IQ

34. Maternal Disease Viruses - Most not harmful Rubella HIV & AIDS
Heart defects, cataracts, deafness
Genital, urinary & intestinal problems
HIV & AIDS
20-30% Mothers pass to infants
Fast growth in infants
Most survive 5 to 8 months

35. Maternal Disease Cont. Herpes viruses Bacterial & Parasitic Diseases
Babies infected during pregnancy or at birth
Bacterial & Parasitic Diseases
Toxoplasmosis from meat or cats
40% transmission
Eye & brain damage

36. Positive Health Activities
Moderate, low impact exercise
Healthy diet - vitamin supplements
Malnutrition causes problems
WIC Program
Low stress
Intense anxiety >> miscarriage, premature birth, low birth weight, respiratory illness, Cleft palate & Pyloric stenosis

37. Domestic Violence 7-8% pregnant women are beaten
Twice the miscarriage rates

38. Rh Factor Mother Rh -, father Rh+, Child Rh+
Antibodies against foreign Rh protein
RhoGam within 72 hours

39. Prenatal Health Care Every month of pregnancy visit MD
2X/Month for the last two months

40. Watch For . . . Diabetes complications Toxemia
Get vaccinations before becoming pregnant

41. Watch This Video

42. The Developing Baby: Conception to Birth
Fertilization: the sperm and egg join in the fallopian tube to form a unique human being. 46 chromosomes combine, 23 from each parent, which pre-determine all of a person's physical characteristics and even some personality characteristics.
Fertilized egg: This picture is of a fertilized egg, only thirty hours after conception. Magnified here, it is no larger than the head of a pin. Still rapidly dividing, the developing embryo is called a zygote at this stage. The embryo floats down from the fallopian tube and towards the uterus, where it attaches at approximately day 4 to 5 post-conception.

43. 5 weeks – Embryo is the size of a raisin
5 weeks – Embryo is the size of a raisin. By day twenty-one, the embryo's tiny heart has begun beating. The neural tube enlarges into three parts, soon to become a very complex brain. The placenta begins functioning. The spine and spinal cord grows faster than the rest of the body at this stage and give the appearance of a tail. This disappears as the child continues to grow.
Embryo at about 6 weeks: Notice the large neural tube and the formation of the heart and other internal organs.
Embryo at approximately 7 weeks: Eyes, fingers, toes and most internal organs have formed, but are not yet fully functional.

44. 7 weeks – Facial features are visible, including a mouth and tongue
7 weeks – Facial features are visible, including a mouth and tongue. The eyes have a retina and lens. The major muscle system is developed and the unborn child moves as if practicing. The child has its own blood type, distinct from the mother's. These blood cells are produced by the liver now instead of the yolk sac.
Embryo in Amniotic sac
Embryo at 8 weeks Amniotic Sac Placenta
8 weeks – The unborn child, called a fetus at this stage, is about half an inch long. The tiny baby is protected by the amniotic sac, filled with fluid. Inside, the child swims and moves gracefully. The arms and legs have lengthened, and fingers can be seen. The toes will develop in the next few days. Brain waves can now be measured.

45. 10 weeks – The heart is almost completely developed and very much resembles that of a newborn baby. An opening the atrium of the heart and the presence of a bypass valve divert much of the blood away from the lungs, as the child's blood is oxygenated through the placenta. Twenty tiny baby teeth are forming in the gums; some babies are even born with teeth emerging from the gums.
The baby at 12 weeks: notice the webbing on the fingers, with the digits still fused
Fetus at 12 weeks Vocal chords are complete, and the child can and does sometimes cry silently. The brain is fully formed, and the child can feel pain. The fetus may even suck his thumb. The eyelids now cover the eyes, and will remain shut until the seventh month to protect the delicate optical nerve fibers. Notice head size and chest size in comparison to an adult.

46. 14 weeks – Muscles lengthen and become organized
14 weeks – Muscles lengthen and become organized. The mother will soon start feeling the first flutters of the unborn child kicking and moving within. 15 weeks – The fetus has an adult's taste buds and may be able to savor the mother's meals. Foods the mother eats can affect movement of the baby
Fetus at 4 months or about 16 weeks Face is fully developed and A downy hair covers the skin. Face is fully formed. Eyes are fully formed but not yet functional.
16 weeks – Five and a half inches tall and only six to 1- ounces in weight Eyebrows, eyelashes and fine hair appear. The child can grasp with his hands, suck her thumb, kick, or even somersault.

47. 20 weeks – The child can hear and recognize her mother's voice
20 weeks – The child can hear and recognize her mother's voice. Though still small and fragile, the baby is growing rapidly and could possibly survive if born at this stage. Fingernails and fingerprints appear. Sex organs are visible. Using an ultrasound device, the doctor can tell if the child is a girl or a boy. This is a a baby girl.
5 months old Beginning to form hair on all body parts Definite sleep/awake cycles now. REM sleep occurs.
Again at 5 months Approximately 8-10 inches long and 1 to 2 pounds Body position is often still “head up” Baby is viable at this point with at least a 50/50 chance of survival outside the womb.
24 weeks – Seen here at six months, the unborn child is covered with a fine, downy hair called lanugo. Its tender skin is protected by a waxy substance called vernix. Some of this substance may still be on the child's skin at birth at which time it will be quickly absorbed. The child practices breathing by inhaling amnionic fluid into developing lungs.

48. 30 weeks – For several months, the umbilical cord has been the baby's lifeline to the mother. Nourishment is transferred from the mother's blood, through the placenta, and into the umbilical cord to the fetus. If the mother ingests any toxic substances, such as drugs or alcohol, the baby receives these as well.
7 months. Room is getting tight at this point. The baby is less able to move, squirms and pushes more than flutters and kicks. Most babies begins to get into a head down position getting ready for birth.
32 weeks – The fetus sleeps 90-95% of the day with REM sleep dominating the sleep cycle, an indication of dreaming. The baby is very viable at this point, with a 75% or higher chance of survival. If the baby is born, the concerns are with adequate lung development. Final lung development does not occur until about 37 weeks.

49. Birth at weeks 40 weeks is normal gestation The baby weighs on average 7 lbs. and is 20 inches long. At birth the baby can see, hear, move and recognizes the voices of her parents or others who have been near the mother.
A healthy newborn arrives in the world She is immediately checked over, given an Apgar score and then presented to her parents. Often the father or other important family member is asked to cut the umbilical cord.
A new child is welcomed into the world