teratogens

• Teratogenic agent (teratogen) - causes physical defects in the developing embryo

  • Some hormones
  • Antibiotics
  • Oral anticoagulants 
  • Anticonvulsants
  • Anti-tumour drugs
  • Thyroid drugs
  • Thalidomide
  • LSD (lysergic acid diethylamide)
  • Marijuana
• Effects of teratogens vary significantly depending on : 

  • Substance
  • Dose 
  • Stage of development
• ALCOHOL

  Foetal alcohol syndrome (FAS) : term used to describe the effects of foetal exposure to alcohol

  • 1 in 1000 births may be affected by FAS
• ALCOHOL

  Unlikely that an alcoholic drink now and then causes harm to developing baby women who are pregnant, or planning pregnancy, are advised to not to drink alcohol
• ALCOHOL

  Excessive alcohol intake, especially ‘binge drinking’ early in pregnancy, causes : 

  • Lower than normal birth weight
  • Slow growth before and after birth
  • Small head
  • Irregularities of the face (e.g. narrow eye slits, sunken nasal bridge)
  • Defects of heart and other organs
  • Malformed arms and legs
  • Intellectual disabilities
  • Behavioural problems (e.g. hyperactivity, extreme nervousness, poor attention span)
• SMOKING

  Smoking causes : 

  • Lower birth weight 
  • Increased risk of miscarriage
  • Gastrointestinal problems when breastfed 
  • Respiratory problem (e.g. bronchitis, pneumonia) 
  • Sudden infant death syndrome (SIDS)

  If smoking is resumed after birth, there is still an increased risk of

  SIDS
• CHEMICALS

  Thalidomide : chemical originally developed for use in sleeping pills

  Also found to be effective in the prevention of morning sickness 

  Causes limb malformations - led to its discovery as teratogen
• CHEMICALS

  Thalidomide acts on the embryo between 28th - 42nd days of development, when future limbs are forming

  The arms are the first to develop, followed by the legs - may be why thalidomide affects the arms more frequently than the legs
• OTHER DRUGS

  Illegal drugs (e.g. heroin, LSD) and many medicinal drugs, can cause damage to foetus when taken during pregnancy

  Many drugs cause most harm early in pregnancy, when pregnancy is unknown
• OTHER DRUGS

  Sexually active women not using contraception should be careful about using drugs before seeking medical advice

  Read side effects label carefully to ensure no risk
• RUBELLA

  Viral infection frequently contracted by school-aged children

  Fairly mild, but highly infectious
• RUBELLA

  if contracted by a pregnant woman it can cause child to be born : 

  • Deaf
  • Blind
  • With heart malformations 
  • Brain damage

  Rubella virus tends to grow in tissues that are just forming

  • 9/10 babies infected during first 10 weeks have major problems
• RUBELLA

  Risk of damage decrease as pregnancy progresses

  • 61% if infection occurs in the fourth month
  • 10% towards the end of the pregnancy
• RUBELLA

  MMR vaccine (measles, mumps, rubella) is given at 12 months and again at 18 months, providing lifelong protection against rubella