Demonstrate insight and understanding into the various environmental factors that influence the pre – natal period

1. Human development
Study Unit3
By C Settley

2. Learning Outcomes
• Demonstrate insight and understanding into the various
environmental factors that influence the pre – natal
period
• Discuss the effects of the following environmental factors
on the prenatal period:
• Age of the parents
• Nutrition of the mother
• Radiation Rhesus factor
• Diseases in the pregnant woman
• The use of medication and drugs
• The emotional state of the mother

3. The Germinal Period
• Begins with conception and lasts from one to
two weeks
• Within approximately 24-36 hours after
conception the zygote divides into 2 cells, these
divide into 4 and so on
• While cell development takes place, the cell
mass moves slowly through the fallopian tubes
and reaches the uterus. In the uterus the cell
mass attaches itself to the uterine mucous
membrane (known as implantation)

4. The Embryonic Period
• Lasts from implantation until about 8 weeks after
conception
• The developing organism is now known as an
embryo

5. The Fetal Period
• Lasts from the end of the embryonic stage until
birth
• Skeletal development occurs
• And due to the movement of above, the
organism is now known as a fetus

6. Pre Natal Development
• Prenatal development is the process in
which an embryo or fetus (or fetus)
gestates during pregnancy. Normal
prenatal development lasts about 38
weeks and is divided into three stages:
germinal, embryonic, and fetal

7. Pre Natal Development
• The growth that happens during the nine
months of prenatal development is nothing
short of astonishing, but this period is also
a time of great vulnerability.
• Fortunately, the effects of many of these
hazards can be greatly lessened or even
avoided entirely.
• While dangers do exist, the vast majority
of babies are born healthy.

8. The effects of the age of the parents during
the prenatal period:
• Two time periods are of special interest:
adolescence and the thirties and beyond.
• Infants born to adolescents are often premature.
• The mortality rate of infants born to adolescent
mothers is double that of infants born to mothers
in their twenties.
• Down Syndrome, a form of mental retardation, is
related to the mother's age

9. The effects of the age of the parents during
the prenatal period:
• By age 40, the probability is slightly over 1
in 100.
• By age 50, it is almost 1 in 10.
• The risk is also higher before age 18.
• Women also have more difficulty in
becoming pregnant after the age of 30

10. The effects of the nutrition of the mother
during the prenatal period:
• Women who begin pregnancy underweight, eat
poorly during pregnancy, and consequently do
not gain at least 1.5 kilograms per month in the
second and third trimesters
• They run a much higher risk of having low birth
weight babies.
• Research indicates that obese women should
gain seven to 11 kilograms during pregnancy;
normal-weight women 11 to 16 kilograms; and
underweight women even more.

11. The effects of the nutrition of the mother
during the prenatal period:
• Beyond overall weight, certain nutrients defend
against low birth weight, including zinc, iron, and
folic acid.
• Indeed, malnutrition (not age) is the primary
reason young teenagers tend to have small
babies.
• They tend to eat unhealthily, and because their
own bodies are still developing their diet is
inadequate to support the growth of two.

12. The effects of Radiation Rhesus factor
during the prenatal period:
• Death of the fetus is the main radiation effect
after exposures during the pre-implantation
period
• With a genetic predisposition for certain
developmental defects the rate of such defects
can be increased by exposures to ionizing
radiations
• Significant increases of malformations have
been observed after certain radiation doses

13. The effects of Radiation Rhesus factor
during the prenatal period:
• Exposures during the zygote stage lead to dose effect
relations without a threshold. It appears possible that
such effects can also occur in humans when a genetic
predisposition exists in individuals. These are rare cases
• Radiation exposures during the pre-implantation period
can increase genomic instability (Genomics is a
discipline in genetics that applies recombinant DNA,
DNA sequencing methods, and bioinformatics to
sequence, assemble, and analyze the function and
structure of genomes (the complete set of DNA within a
single cell of an organism)

14. The effects of diseases on the pregnant
woman during the prenatal period:
• Many diseases are capable of injuring a growing
fetus.
• For example, doctors discovered that when a
mother contracts rubella (also known as the
German measles) early in her pregnancy, her
child might suffer blindness, heart abnormalities,
and brain damage as a result. Since then,
immunizations have dramatically decreased in
incidence of rubella and lowered the number of
children affected by the illness.

15. The effects of diseases on the pregnant
woman during the prenatal period:
• Maternal diseases and infections can produce
defects by crossing the placental barrier.
• Syphilis is more damaging later in prenatal
development, four months or more after
conception. Rather than affecting organ
development as Rubella does, syphilis damages
organs after they have formed. The importance
of the mother's health to the health of her
offspring is nowhere better exemplified than
when the mother is infected with HIV

16. The effects of the usage of medication and
drugs during the prenatal period:
• Harmful substances such as drugs or radiation that invade the
womb and result in birth defects are called teratogens.
• Teratogens are especially damaging in the embryonic stage
because it is a critical period in prenatal development. Later, during
the fetal stage, the environment provided by the mother affects the
baby’s size, behaviour, intelligence and health, rather than the
formation of organs and limbs In the past, doctors believed that the
placenta served as a barrier to protect the growing fetus against
toxins
• Today, doctors recognize the effects of many medicinal drugs
including anticonvulsants and most hormones
• Because of the potential dangers, it is important for pregnant
women to avoid any medications that have not been specifically
recommended by their doctor.

17. The effects of the usage of medication and
drugs during the prenatal period:
• You've also probably noticed that most television ads for
new medications include some type of statement
warning that women who are pregnant or who may
become pregnant should avoid taking the certain drugs.
• Because such medications are thought to be able to
affect the fetus as early as 10 to 14 days after
conception.
• Fortunately, because doctors and mothers-to-be are far
more aware of the potential dangers, the rates of
medication-linked birth defects have been reduced
considerably over the past few decades.

18. The effects of the usage of medication and
drugs during the prenatal period:
• Psychoactive Drugs
• Unfortunately, prenatal damage caused by psychoactive
drugs such as alcohol, cocaine, heroin, inhalants, and
tobacco are still far too common.
• All psychoactive drugs have a deleterious effect on
prenatal development leading to problems including low
birth-weight, premature birth, and impaired brain
development.
• The effects of such drug use can lead to both short-term
and long-term deficits.

19. The effects of the usage of medication and
drugs during the prenatal period:
• Babies exposed to psychoactive drugs in-utero may
show signs of drug withdrawal after birth, such as crying,
startling, difficulty sleeping, and erratic eating.
• As they continue to develop and grow, these children
may face learning problems such as an inability to pay
attention, poor self-control, increased irritability, or
even major developmental delays.
• Tobacco use can result in low birth-weight as well as an
increased risk of abnormalities such as urinary tract and
limb malformations.

20. The effects of the usage of medication and
drugs during the prenatal period:
• Alcohol use during pregnancy causes fetal
alcohol syndrome which is characterized by
facial abnormalities including a smaller than
average head size, a flattened nose, wide
spacing between the eyes, and a narrow upper
lip.
• Fetal alcohol syndrome also results in
intellectual impairments, impaired physical
growth, learning disabilities and behavioral
problems.

21. The effects of the usage of medication and
drugs during the prenatal period:
• Also prevalent are a higher incidence of preterm
births and lower birth weights. Respiratory
problems and sudden infant death syndrome are
also more common among the offspring of
mothers who smoked during pregnancy
• Tranquilizers taken during the first three months
may cause cleft palate or other congenital
malformations

22. Medication Potential Harm Effects
Alcohol FAS
Nicotine Miscarriage, premature/low weight births
Sedatives Problems with sucking and breathing
Opiates (pain killers) Convulsions, breathing problems,
behavioural problems
Cocaine Prem. births, low birth weight, small skull
Aspirin Fetal bleeding, low birth weight
Anti- Epileptics Physical deformities, retarded growth
Anti- depressants Mental retardation, Physical deformities
Vitamin A Physical deformities

23. The effects of the emotional state of the
mother during the prenatal period:
• The mother's stress can be transmitted to the fetus.
• When a pregnant woman experiences intense fears,
anxieties, and other emotions, physiological changes
occur in the fetus.
• These include changes in respiration and glandular
secretions.
• For example, producing adrenaline in response to fear
restricts blood flow to the uterine area and may deprive
the fetus of adequate oxygen.
• Also, reassuring the mother of fetal well-being has
positive outcomes for infants

24. References
•http://psychology.about.com/od/early-child-
development/a/environmental-influences-
on-prenatal-development.htm

25. Activities