Use of drugs in pregnancy and breastfeeding Flashcards
What are the stages of pregnancy?
First trimester (weeks 1-12):
Fertilised egg travels along fallopian tube dividing constantly until it reaches the uterus and implants in the lining.
Organs begin to develop.
Second trimester (weeks 13-27):
Muscles and bones continue to develop.
Growth occurs rapidly.
All essential organs have formed.
Third trimester (weeks 28-41):
Movement increases and babies begin to practice breathing by moving their diaphragm.
Weight increases significantly.
Bones harden and skin thickens.
What are the effects of drugs in the different trimesters?
First trimester:
Often thought of as the main time of concern when using drugs since some drugs used in the first trimester can cause structural congenital malformations or be teratogenic.
A teratogen is something that causes structural or functional abnormalities in a foetus or child.
Second and third trimester:
Use of drugs at this stage can lead to effects on the growth and functional development of the foetus.
Some drugs given very late in pregnancy can lead to adverse effects after delivery including withdrawal symptoms (e.g. opiates).
What are teratogens?
Any drug or substance that can cross the placenta and cause a congenital malformation is known as a teratogen.
Teratogens can cause structural or functional abnormalities in a foetus or child after birth.
Teratogens will not always cause an issue – e.g. thalidomide caused abnormalities in less than half of foetuses exposed during the critical period.
Teratogenicity is usually dose dependent.
What are some physiological changes that occur during pregnancy?
BP initially decreases and increases back to pre pregnancy levels at term. There is an associated increase in heart rate and stroke volume.
Changes in the coagulation cascade can lead to increased risk of a VTE.
Increase in renal blood flow means renally excreted drugs may be cleared more rapidly.
Plasma volume increases and albumin levels decrease affecting drug levels of highly protein bound drugs.
Altered activity of hepatic enzymes can affect drugs metabolised in the liver.
A decrease in lower oesophageal sphincter pressure and a decrease in GI motility can lead to bloating, reflux and constipation.
Can sodium valproate be used during pregnancy?
Sodium valproate is a known teratogen and is associated with foetal malformations and developmental delays.
In addition, many other antiepileptic drugs can lead to folate deficiency which is linked to the development of neural tube defects such as spina bifida.
In 2018, warnings were strengthened and now must be present on boxes.
However, it is important to control epilepsy during pregnancy since frequent or prolonged maternal seizures can cause miscarriage and premature labour and deprive the foetus of oxygen and nutrients.
Women of child bearing age must be on a pregnancy prevention programme (PPP).
Can isotretinoin be used during pregnancy?
Retinoids, including isotretinoin are contraindicated in pregnancy due to a high risk of serious congenital abnormalities and life threatening birth defects.
It should only be used for severe acne resistant to standard therapy and given under specialist supervision.
Women of child bearing age who are using isotretinoin should be enrolled on a pregnancy prevention programme.
Can antidepressants be used during pregnancy?
Women with mental health conditions may receive conflicting advice on how to manage their condition and whether or not they should continue to take medicines.
Women who become pregnant may suddenly stop taking their medication since they may feel this is the safest thing to do.
Leaving a condition such as severe depression untreated can have adverse effects on the pregnancy outcome and can affect the developing relationship between the mother and child.
TCAs and SSRIs have not been associated with a significant risk of foetal abnormalities.
If patient is willing and suitable, consider talking therapies.
Can analgesics be used during pregnancy?
Pain is common in pregnancy.
Paracetamol is safe and effective and recommended first line for mild to moderate pain.
Use of NSAIDs in late pregnancy can lead to premature closure of the ductus arteriosus which can lead to congestive heart failure.
Use of opiates in late pregnancy can lead to respiratory depression and withdrawal symptoms in the neonate but are not linked to an increased risk of congenital abnormalities.
Which opioids can be given during pregnancy?
Codeine is first choice if an opiate must be used.
Strong opioids used during labour can lead to neonatal issues.
Opioids can also exacerbate constipation, nausea and vomiting which are already common during pregnancy.
Can codeine be used whilst breastfeeding?
Use of codeine is not recommended in breastfeeding women due to a fatal case of morphine toxicity in a breastfed infant – codeine is metabolised into morphine in the body.
Ultrarapid metabolisers convert more codeine into morphine leading to potential toxicity.
Alternative opioids may be safer e.g. dihydrocodeine and tramadol but should be used under close supervision and the mother and infant monitored.
Replace opioid with non-opioid analgesic if adverse effects develop in infant and withhold breastfeeding.
Neonates and young infants are most at risk due to immature hepatic enzyme function.
Can ibuprofen and paracetamol be used whilst breastfeeding?
Ibuprofen:
Ibuprofen is one of the analgesics of choice when breastfeeding.
Only very small amounts pass into breast milk which are lower than the doses that would be given to infants directly.
Does not accumulate.
Paracetamol:
Paracetamol is the simple analgesic of choice.
Very small amounts pass into breast milk and again are lower than the dose that would be given directly.
Does not accumulate.
Avoid co-codamol and caffeine containing combination products.
Avoid decongestant combination products.
Can aspirin be used whilst breastfeeding?
Aspirin passes into breast milk in small amounts.
No adverse effects when used at low dose (75-150mg) when used as an antiplatelet agent.
Data is limited and therefore should be used with caution and infants monitored.
Unknown whether small amounts of aspirin present in breast milk could cause Reye’s syndrome in a breastfed infant.
Withhold breastfeeding if infant develops a fever or stop aspirin.
Can antidepressants be used whilst breastfeeding?
Consider non pharmacological interventions first, e.g. talking therapies, guided self help.
The SSRI sertraline is a suitable choice since it has a short half life and low levels of the drug transfer into breast milk but use is off licence.
Fluoxetine has a longer half life leading to a risk of accumulation in the infant.
There is a risk of maternal toxicity and significant adverse effects with tricyclic antidepressants therefore these are generally prescribed less for post natal depression.
Can contraceptives be used whilst breastfeeding?
Lactational amenorrhoea can be up to 98% effective in preventing pregnancy if the mother is fully breastfeeding, the baby is under 6 months and the mother has no periods.
Contraceptives can be used during breastfeeding and progesterone only methods are the preferred hormonal contraceptive.
There is a low risk of inhibition of early lactation if they are started before 6 weeks after delivery.
Combined hormonal contraceptives can be used from 6 weeks after childbirth but have a significant suppressant effect on milk production so should only be used once the infant is weaned or from 6 months post partum.
