Prenatal development occurs in three stages - the germinal stage, embryonic stage, and fetal stage. In the germinal stage from weeks 1-2, the zygote divides into cells and implants in the uterus. The embryonic stage from weeks 3-8 sees development of major organs and gender determination. The fetal stage from week 9 until birth refines organs for extrauterine life. Common issues that can impact development include genetic disorders, chromosomal abnormalities, maternal diseases, drugs/toxins, and malnutrition. Screening and some prenatal treatments exist to assess and address certain risks and conditions.

1. Prenatal Development

2. Three Stages of development
• The Germinal Stage
• The Embryonic Stage
• The Fetal Stage

3. Germinal Stage
• First two weeks of gestation.
• Day 4, the zygote is divided into dozens of cells
• Day 5, becomes hollow, fluid-filled ball called a blastocyst
• Day 6/7, comes into contact with uterine wall.
• By day 12, buried in the uterine tissue

4. Embryonic Stage
• Nervous system cells create a neural tube. Week 4 it forms the brain.
• Between weeks 4-6 gender is determined.
• Week 7, bones are beginning to harden and muscles are maturing.
Can keep a somewhat upright position.
• Week 8, liver and spleen make and filter blood cells; heart pumps
blood to rest of body.

5. Fetal Stage
• Refines organs that are important to have life outside of the womb.
• By week 23, most fetuses are viable, though most babies won’t
survive if born this early.
• Recognition of mom’s voice.

6. Issues in Prenatal Development
• Genetic Disorders
• Chromosomal Errors
• Teratogens

7. Genetic Disorders
• Autosomal Disorders or Sex-linked Disorders
- caused by recessive genes
• Are usually inherited
• Autosomal Dominant takes only one mutated copy of the gene
• Autosomal Recessive takes two copies of the mutated gene
• X-linked Dominant
• X-linked Recessive
• Ex: Huntington’s disease, Cystic fibrosis, Hemophilia

8. Chromosomal Disorders
• Most common is the XXY pattern, Klinefelter’s syndrome
• Turner’s syndrome with a single-X pattern (XO)
• Boys with Klinefelter’s syndrome experience male and female
changes.
• Turner’s syndrome are anatomically female, stunted growth, and
usually sterile.
• Both are not associated with the mothers age

9. Teratogens: Maternal Diseases
• HIV can be passed from mother to fetus
• Other STD’s can cause congenital anomalies
• Cancer can cause a fetal or placental tumour
• Chicken Pox can cause scars or eye damage
• Parvovirus can cause Anemia

10. Teratogens: Drugs
• Thalidomide in the 60s caused malformations of the limbs in
thousands of fetuses exposed.
• Mothers who smoke, put their babies at risk of a low-birth weight,
miscarriages, still-born babies, pre-mature birth, and neonatal death
• Fetal Alcohol Syndrome: generally smaller in all respects. Frequently
have heart anomalies and hearing losses.
• 60-80% of babies with addict mothers are likely to be addicted to that
drug as well, suffer from withdrawal and have high-pitched cries

11. Teratogens: Other Harmful influences
• Important for a pregnant women to get enough calories and protein
as to prevent malnutrition; increased risk of low-birth weight.
• Pregnancy risks increase as women get older
• Erratic blood sugar can cause Damage to the fetus’s nervous system
or to grow too fast.
• Severely distressed mothers are more likely to have their children
suffer from emotional or cognitive disorders

12. Paternal Influences
• Father’s pass on 55 mutations to their children
• Sperm affected up to three months before conception can impact the
prenate.
• Father’s age has been raised as a concern; a study of Icelandic
families revealed that fathers pass on more mutations with advancing
age.
• Possible cause of autism and schizophrenia.

13. Fetal Assessment and Treatment
• First trimester screening for possible development complications
• Chorionic Villus Sampling and Amniocentesis can be used to identify
chromosomal errors and many genetic disorders prior to birth.
• Fetoscopy: used to correct some anomalies surgically

14. Relevance to Me personally
• One of my friends is having her baby on Nov 4th.
• Several other friends have and will be pregnant in the future
• One day I may be pregnant so knowing this stuff could be important.

15. Helping in a Future Profession
• Everyone will have to help a woman who is pregnant.
• As a counselor or psychologist I might have a patient who is pregnant
and is worried about things.

16. • D. Boyd, P. Johnson, H. Bee, Lifespan Development, pgs 67-70, 73 – 85
• https://en.wikipedia.org/wiki/Genetic_disorder