Prescribing in Pregnancy

Question 1

What is teratogenicity?

Answer 1

The ability of a drug to cause a structural abnormality in the 1st trimester.

Question 2

What is fetotoxicity?

Answer 2

The ability of a drug to cause a functional abnormality in the 2nd and 3rd ​trimesters.

Question 3

What are the physiological changes in pregnancy which may alter the pharmacokinetics of a drug?

Answer 3

• Increased circulatory volume
• Increased 3rd space availability
• Increased fat content
• Decreased albumin
• Increased gFR
  
  • This can lead to increased clearance of drugs which are renally excreted.

Question 4

What are the classes of drugs associated with teratogenicity?

Answer 4

• Anti-convulsants
• Antibiotics (some)
• Anti-coagulants
• Anti-metabolites
• Anti-psychotics
• Androgens
• Acne drugs
• Alcohol

Question 5

Which analgesics can be used in pregnancy?

Which should be avoided?

Answer 5

• Probably safe
  
  • Paracetamol
  • Codeine
  • Tramadol
• Avoid
  
  • ​NSAIDs. Can cause premature closure of the ductus arteriosus.
• Caution
  
  • ​Opioids. If taken around the time of delivery, may lead to neonatal respiratory depression. Long-term use by the mother may lead to neonatal withdrawal symptoms.

Question 6

Which GI drugs can be used in pregnancy?

Which should be avoided?

Answer 6

• Probably safe
  
  • ​Ranitidine
  • Cyclizine (1st line anti-emetic)
  • Promethazine (1st-line anti-emetic)
  • Ondansetron
  • Metaclopramide
• Avoid
  
  • ​PPI

Question 7

Which cardiovascular drugs can be used in pregnancy?

Which should be avoided?

Answer 7

• Probably ok
  
  • ​Methyldopa
  • Labetalol
• Avoid
  
  • ​ACE-I. Teratogenic in the 1st trimester
  • Thiazides

Question 8

Which anticoagulants can be used in pregnancy?

Which should be avoided?

Answer 8

• Probably safe
  
  • ​LMWH (does not cross placenta).
• Avoid
  
  • ​Warfarin. Teratogenic and causes warfarin embryopathy.

Question 9

Describe the use of anti-epileptic drugs in pregnancy.

Answer 9

• Review history and medication, as all AEDs are associated with an increased risk of congenital malformations.
• However, the vast majority of pregnant women on AEDs give birth to healthy babies.
• Poorly controlled epilepsy is potentially dangerous to the mother and fetus.
• Women on AEDs are advised to take 5mg folic acid daily at least 6 weeks prior to conception.
• Sodium valproate is particularly teratogenic.

Question 10

What is use of cocaine in pregnancy associated with?

Answer 10

Fetal growth restriction and placental abruption.

Question 11

What is the use of ecstasy in pregnancy associated with?

Answer 11

Poorer mental and motor development in infants at 12 months old.

Question 12

What is the use of heroin in pregnancy asociated with?

Answer 12

Fetal growth restriction. Also associated with withdrawl symptoms when born; this leads to symptoms such as sleep problems, irritibility, seizures, tremors and problems feeding.

Question 13

What are the risks associated with smoking in pregnancy?

Answer 13

• Miscarriage
• Stillbirth
• Prematurity
• Low birth weight
• Sudden infant death syndrome
• Increased infant mortality

Question 14

What are the risks associated with alcohol in pregnancy?

Answer 14

• Fetal alcohol syndrome
  
  • Poor growth
  • Facial abnormalities
  • Learning and behavioural problems