Lecture 1 - Prenatal Development Flashcards
Prenatal
Before birth
Perinatal
Around time of birth
Three stages of prenatal development
Zygote
Embryo
Foetus
Risks in Prenatal environment
Teratogen: An environmental agent that causes prenatal damage
Effects during critical/sensitive periods
Effects are specific
Longer exposure is worse
Some have no effect on mother
Maternal/foetal genes may counteract effect
3-8 weeks= most likely major effects, structures being developed
8+= more about function so less likely to be effected, more about brain developing
Prescription Drugs Legal Substances Environmental Toxins Infectious Diseases Maternal Factors
Stages of prenatal development - Zygote
0-2 weeks -> conception to implantation
Ovary-> fillopian tube –> uterus (week)
Unportectected sex, sperm up both-> fertilised in tube, develop in fillopian tubes (zygote)
Sperm in = chemical barrier
Dividing and devloping
Week further to implant
Stages of prenatal development - Embryo
3-8 wks -> structural development
Neural tube (elongation of ball of cells -> becomes brain & spinal cord
Placenta, Umbilical Cord, Amniotic Sac
Miscarriage risk highest
Amniotic sac
Fluid-filled membrane protecting embryo
Placenta
Disc-like structure connecting embryo to uterus
Umbilical cord
Tube connecting embryo to placenta
Provides oxygen & nutrients
Removes carbon dioxide & waste
Stages of prenatal development - Foetus
9-38 wks -> functional development Brain development Responds to stimulation Reflexes develop Brain devlopes most- ceribral cortex and front of brain
Can tell sex
Wk 12
Can feel movement
Wk 17-20
Viability
Can survive outside the womb
wk 22-26
Last few weeks is only development of body fat etc -> temperature regulation (hence need for incubator to do this if premature)
Teratogens: Prescription Drugs
Thalidomide
Drug for morning sickness (1957-61)
Caused structural abnormalities in limbs & face
DES
Hormone to prevent miscarriage (1947-64)
Linked to reproductive problems & cancers in offspring
Gene dependent
Teratogens: Legal Substances
Caffeine
Miscarriage, low birth weight (LBW)
Avoid > 200mg
Tobacco
Chemicals in smoke -> miscarriage & prematurity
Nicotine affects placenta -> poor nutrition
-> LBW
Carbon monoxide -> reduce oxygen carrying in baby too
Alcohol
Foetal Alcohol Syndrome (FAS) -> Foetal Alcohol Spectrum Disorder (FASD)
Stunted growth Physical defects Often mental retardation Wont catch up Mental impairement perminantly
Alcohol displaces oxygen -> effects baby
Last trimester worst
Brain develops throughout and so can be effected at any time
Guidlines change even for normal drinking now