Prenatal Development

Question 1

Prenatal – what does this mean?

Answer 1

Prenatal = before (pre) birth (natal)
9-month period from conception to birth constitutes the first stage in human development and is divided into 3 substages

Question 2

1st stage of Prenatal period

Answer 2

Germinal stage
0-2 weeks
Sperm penetrates egg to form a zygote
This contains 23 pairs of chromosomes – inherited aspects from mother & father (50/50). These make up the individual’s genotype and phenotype
Zygote following cell differentiation becomes a blastocyst and begins to implant into the wall of the uterus – at which point the germinal stage ends.

Question 3

2nd stage of Prenatal period

Answer 3

Embryonic stage
week 3 to around week 7/8
Cell differentiation continues until 350 different cell types are formed
Ectoderm, endoderm & mesoderm cells form different bodily aspects
By week 8, embryo is 2cm in length
All changes reflect choreographed changing patterns of cells to achieve the species-typical shape of the organism

Question 4

3rd stage of Prenatal period

Answer 4

Foetal stage
Week 8/9 to week 38-40
Coincides with major developments of the nervous system
Rapidly takes on distinctively human characteristics & by week 12 is easily recognisable
By week 16, embryo is 15-17cm but cannot survive outside of the mother
Foetus continues to develop for the normal 40 week gestation period

Question 5

The prenatal environment key points

Answer 5

Critical for normal development
(see Knopik et al., 2016)

Changes to environment can be catastrophic for foetus and neonate

But, foetal behaviour also contributes to normal development – not simply a matter of automatic maturation, more than just a reflexive responder

Question 6

Prenatal risk factors – Teratogens

Answer 6

Exposure to teratogens during prenatal stage can significantly raise the risk of birth defects
Teratogens:
“Environmental agents that have the potential to
cause harm during prenatal development”
(Siegler et al., 2003)

Question 7

Teratogens factors

Each of these aspects pose as potential risk factors for a developing child:

Answer 7

Legal drugs
Nutrition
Illegal drugs
Disease
Disease
Pollutants
Maternal Stress
Maternal age

Question 8

Teratogens are influences by???…

Answer 8

Timing of exposure
Amount and duration of exposure
Age
Exposure to other teratogens
Individual differences in susceptibility in the mother and the foetus

Question 9

Rubella

Answer 9

AKA German measles
Rubella is caused by a type of virus known as a togavirus
Spread in a similar way to a cold/flu, droplets of moisture from the nose or throat of infected individual

Generally mild unless contracted during pregnancy, when there is a 90% chance of the foetus getting congenital rubella syndrome (CRS)

Question 10

Rubella defects can cause

Answer 10

The baby can be born with multiple defects if it lives (miscarriage common)
Eye problems – such as cataracts(cloudy patches on the lens of the eye)
Deafness
Heart Abnormalities
Brain Damage

Question 11

Zika Virus

Answer 11

Mosquito-borne virus

Infection, especially in the 1st trimester can cause microcephaly and other foetal brain defects

Between Oct 2015 – Jan 2016 almost 4000 cases of babies born with microcephaly in Brazil

Question 12

Teratogens - Legal drugs: Thalidomide

Answer 12

considered a ‘wonder drug’ for morning sickness and was being prescribed worldwide
Late 1950s, children began to be born with shocking disabilities
The most renowned disability wasPharcomelia the name given to the flipper-like limbs which appeared in children
‘Thalidomide Babies’

Question 13

Teratogens – Legal drugs: Primodos

Answer 13

pregnancy testing drug given to women in 1960s/70s.Consisted of two pills, inducing a period in women who were not pregnant

Question 14

Teratogens – Legal drugs: Alcohol

Answer 14

Foetal Alcohol Syndrome (FAS)
mostharmful for the baby in the first 3 months of pregnancy
affect baby’s development, particularly the brain and spinal cord

Question 15

Foetal Alcohol Syndrome (FAS) – symptoms:

Answer 15

Smaller than average head
Poor growth – weight and height
Changes facial features (all smaller than usual)
Movement/Co-ordination issues (Cerebral Palsy)
Learning difficulties
Mood/attention/behavioural issues (ADHD)
Weaker organs and immune system
Hearing and vision

Question 16

Prematurity

Answer 16

Also referred to as Preterm birth
Defined by WHO (2015) as ‘babies born alive before 37 weeks of pregnancy are completed’
Leading cause of death in children <5 years

Question 17

3 sub-categories of prematurity:

Answer 17

Extremely preterm (<28 weeks)
Very preterm (28 weeks to <32 weeks)
Moderate to late preterm (32 weeks to <37 weeks)