Prenatal Development

Question 1

Conception

Answer 1

… when a male’s sperm fertilizes the female’s egg

• At this point, the egg blocks all other sperm
• Women are born with all the eggs they will ever have (1/5000 actually mature)
• Men begin producing sperm at puberty and produce it 24/7 for the rest of their life

Question 2

Genetics - Chromosome and genes

Answer 2

This new one-cell entity contains 23 pairs of chromosomes…one member of the pair from the mother and the other from the father

Each chromosome contains thousands of genes…either individually or in combination, genes produce the particular characteristics of each person

Genes are composed of sequences of DNA (deoxyribonucleic acid) molecules

Some genes are responsible for the development of systems common to all humans (heart, circulatory system, brain, lungs, etc.), while others control characteristics that make each human unique (like eye color, height, facial features, etc.)

Sex is also determined by the combination of genes (the 23rd chromosome)

Question 3

prenatal development - Zygote

Answer 3

fertilized egg

• Fewer than ½ survive the 1st 2 weeks
• The first stage of prenatal development.
• Lasts about two weeks and consists of rapid cell division.
• About 10 days after conception, the zygote will attach itself to the uterine wall.
• The outer part of the zygote becomes the placenta (which filters nutrients).

Question 4

prenatal development - Embryonic stage

Answer 4

(weeks 2-8) Lasts about 6 weeks.
- Heart begins to beat and the organs begin to develop
- At 2 weeks, zygote becomes an embryo
- By 4 weeks, embryo has developed a rudimentary beating heart, brain and intestinal tract (these organs are very primitive…but can be recognized)
- By 8 weeks, embryo is about an inch long…has arms, legs and face that are distinct

Question 5

prenatal development - Fetal stage

Answer 5

(from 8 weeks to birth)
- At week 8/9, now called a fetus
- By around 4 months, fetal movement strong enough to be detected by mother
- At around 6 months, eye lids open and fetus has well-developed grasp and taste buds
- The fetus by about the 6th month, the stomach and other organs have formed enough to survive outside of mother.
- At this time the baby can hear (and recognize) sounds and respond to light.

Question 6

prenatal development - age of viability

Answer 6

Fetus reaches age of viability or the point at which it can survive if born prematurely at 24 weeks (about 50% of premie babies survive at this age and % increase as each week passes)

Fetus continues to grow and gain weight during the last two months…at the end of a normal 38 week (9 ½ month) pregnancy, fetus typically weighs around 7 lbs and is about 20 inches in length

Question 7

prenatal influences - Genetic factors - Phenylketonuria (PKU)

Answer 7

inability to breakdown protein

Question 8

prenatal influences - Genetic factors - Tay-Sachs disease

Answer 8

the body is unable to break down fat, which causes these substances to build up in and destroy the brain and nerve cells until the nervous system shuts down

• babies usually start exhibiting signs of the disease around 4-6 months old
• children usually die by age of 5
• if parents both carry the genetic defect, the child has a 1 in 4 chance of being born with the disease
  
  • seems to occur most frequently in Central and Eastern European Jews (and descendants)

Question 9

prenatal influences - Genetic factors - Down Syndrome

Answer 9

occurs when a zygote receives an extra chromosome at the moment of
conception…causes intellectual disability (usually in the mild to moderate
range)

Often related to a mother’s age…more common in babies born to
mothers over the age of 35

Characteristic facial features…including upward slanted eyes,
smaller noses, ears and mouth, and sometimes smaller hands and
shorter necks

Often accompanied by other health problems…heart, vision and
hearing

Question 10

prenatal influences - Environment factors - Teratogens

Answer 10

or other factors that can produce birth defects

Question 11

Newborn - Rooting reflex

Answer 11

automatic turn of head when cheek is touched

Question 12

Newborn - Sucking reflex

Answer 12

suck anything that touches lips

Question 13

Newborn - Startle reflex

Answer 13

infant flings arms, fans fingers and arches back in response
to sudden noise

Question 14

Newborn - Babinski reflex

Answer 14

toes fan out when out edge of sole of foot is stroked

These reflexes are lost after first few months of age and are
replaced by more complex behaviors

Question 15

Healthy Newborns

Answer 15

• Turn head towards voices .
• See 8 to 12 inches from their faces.
• Gaze longer at human like objects right from birth.
• Recognize mom’s voice first.

Question 16

Newborn - reflexes

Answer 16

all babies are with a number of reflexes (unlearned, involuntary responses that occur automatically in the presence of certain stimuli

Question 17

Prenatal Influences - Environment - Teratogens - mother’s illness - Rubella (German measles)

Answer 17

Rubella (German measles) can cause blindness, deafness, heart abnormalities and stillbirth

Question 18

Prenatal Influences - Environment - Teratogens - mother’s illness - Syphilis

Answer 18

Syphilis can cause mental retardation, physical deformities, and miscarriage for the mother

Question 19

Prenatal Influences - Environment - Teratogens - mother’s illness - AIDS

Answer 19

AIDS can be passed on to a child prior to birth

Question 20

Prenatal Influences - Environment - Teratogens - Mother’s use of drugs

Answer 20

• Illegal drugs like cocaine can result in baby being born addicted to the drug
• Even some legal drugs can cause fetal abnormalities

Question 21

Prenatal Influences - Environment - Teratogens - Mother’s alcohol and nicotine use - Fetal alcohol syndrome

Answer 21

the condition resulting in mental and growth retardation

• Some physical features associated with FAS – abnormally small, small eyes and upturned nose, and small or abnormally formed brain
• Most have some degree of mental retardation and many exhibit problems with attention span, learning, coordination and behavior

Question 22

Prenatal Influences - Environment - Teratogens - Mother’s smoking

Answer 22

Smoking can lead to fewer nutrients received by the fetus which results in lower birth weight…heavy smoking may affect the brain