Antidepressants are generally indicated in moderate to severe depression and when active management and psychological
therapy have not provided sufficient response. Careful explanation of the benefits and risks of antidepressant treatment
is very important, especially to counteract any potentially incorrect information that the woman may have been exposed
to. For example, a woman could be at serious risk of illness relapse if she stops antidepressant treatment because of
her concerns about infant exposure to the medicine from breastfeeding.
Choice of antidepressant
Choice of antidepressant is mainly determined by current or previous response. A serotonin re-uptake inhibitor (SSRI)
is the usual first choice. Paroxetine, citalopram and fluoxetine are all considered to be compatible with breastfeeding.
There is no evidence to suggest that any particular medicine or class of antidepressant is more effective in this patient
group. The choice of antidepressant is determined by previous response, and whether the woman is breastfeeding or wishes
to (see below). If a woman has been treated, and responded well to an antidepressant during pregnancy, it is usually preferable
to continue with the same agent in the postnatal period. A SSRI is now generally used as the first line antidepressant
as they are better tolerated and safer in overdose than tricyclic antidepressants (TCAs).
Antidepressants for postnatal depression during breastfeeding
A complex relationship exists between postnatal depression and breastfeeding. Depression is less likely to develop in
women who establish and maintain breastfeeding than in those who have difficulties with breastfeeding.15 Women
who develop postnatal depression are more likely to stop breastfeeding, perhaps due to concerns about infant medicine
exposure. Other women may stop taking their antidepressant due to toxicity concerns, without realising the risks of their
Not surprisingly, there are no randomised controlled trials of antidepressant use during breastfeeding, and there is
little evidence on the long-term consequences of infant exposure to antidepressants through breast milk. The safety of
medicine exposure from breast milk is derived from case studies and observational investigations involving small numbers
of women who are producing breast milk.
The relative safety of a medicine taken during breastfeeding is expressed in terms of the weight adjusted maternal dose
(WAMD).16 If the maternal dose of a medicine is 10 mg/kg, a “dose” of 1 mg/kg received via breast milk represents
a WAMD of 10%. If the WAMD is low, the overall medicine exposure to the infant is also low. Arbitrarily, drugs with a
WAMD of 10% or less are considered relatively safe for the infant, but the lower the better. Exceptions are drugs such
as warfarin and cytotoxics which are inherently toxic and any exposure would be considered unsafe.
As well as having a low WAMD, a medicine with a short half-life is desirable as this reduces the risk of accumulation
and allows significant removal of the drug from the maternal circulation between feeds.
The SSRIs and their metabolites pass into breast milk in small amounts, generally below 7% of the WAMD. Infant ingestion
via milk is lowest for paroxetine (WAMD ≈ 2%) citalopram (≈ 7%) and highest for fluoxetine (≈ 10%).17 Fluoxetine,
citalopram and paroxetine are all considered to be compatible with breastfeeding. If a woman has been successfully treated
with fluoxetine or citalopram in pregnancy, and needs to continue treatment after delivery, it is not necessary to switch
to paroxetine as differences in medicine exposure are relatively small. Sedation, poor feeding and behavioural changes
have been rarely associated with exposure to SSRIs via breast milk. Although there is no proven link between the medicine
exposure and these adverse effects, breastfed infants should be monitored, particularly if the mother is taking fluoxetine
or higher doses of any SSRI.
The commonly used TCAs, amitriptyline and nortriptyline have a low WAMD and are considered safe to use in breastfeeding.
However, SSRIs are generally preferred as they are generally better tolerated and have a lower toxicity in overdose.
Doxepin has been associated with some adverse effects in breastfed infants and is not recommended while breastfeeding.
Studies have shown that venlafaxine is excreted into breast milk with a WAMD in the range of 2-9%.17 This indicates
that it is relatively safe in breastfeeding but experience is limited and it is not a first-line choice.
There is no place for synthetic progestogens in the treatment of postnatal depression, and norethisterone is in fact
associated with an increased risk of postnatal depression. Progesterone-only contraceptives should be used with caution
in the postnatal period, particularly in women with a history of depression before or during pregnancy.18
The role of natural progesterone in the treatment of postnatal depression has yet to be evaluated in a randomised, controlled
Some studies have shown modest benefits of oestrogen therapy at late stages of postnatal depression,18 but
it is not recommended as a treatment option in the New Zealand Guidelines.1
Monitoring treatment and follow-up
It is important to monitor response to treatment and adjust if response is inadequate. This will involve good communication
between all practitioners involved in the woman’s care. There are significant risks if untreated depressive illness
in the postnatal period carries forward in to subsequent pregnancy. The next pregnancy should be planned and discussed
with consideration of factors such as the control of the current illness, whether in remission or not, and the need for
continued antidepressant treatment.
Contraceptive advice is important as low libido and breastfeeding can lead the mother in to thinking that conception
is not possible. An unexpected pregnancy during this time can be extremely stressful and compromise the health of mother