Antibiotics Safe During Lactation & Postpartum Depression

Part 1: Antibiotics Safe During Lactation

General Principles

• Relative infant dose (RID): the fraction of maternal dose an infant receives via milk — generally safe if <10%
• Oral bioavailability in the infant (drugs with poor GI absorption, e.g. IV vancomycin, pose minimal risk)
• Infant age and health (preterm or renally compromised infants need extra caution)
• Common minor side effects in the infant: loose stools, colic, diarrhoea — inconvenient but not a reason to stop breastfeeding

Safe Antibiotic Classes (First-Line Choices)

Antibiotics Requiring Caution

Antibiotics to Avoid

• Chloramphenicol (systemic) — risk of bone marrow suppression
• Dapsone — haemolytic anaemia risk in infants
• Linezolid — insufficient data, potential toxicity

Lactational Mastitis

Part 2: Postpartum Depression (PPD)

Definition & Epidemiology

• Formally defined as a major depressive episode within 4 weeks of delivery (DSM-5 uses "peripartum onset" — symptoms from pregnancy through 1 month postpartum)
• Affects ~10–15% of mothers; rates triple among adolescent and inner-city mothers
• Completed suicide is a leading cause of maternal mortality; infanticide, more often associated with postpartum psychosis (PPP), is also a devastating outcome
• Up to 1 in 5 women remain depressed for a year or longer if untreated

DSM-5 Diagnostic Criteria (Major Depressive Episode + Peripartum Onset)

1. Depressed mood most of the day, nearly every day
2. Markedly diminished interest or pleasure
3. Appetite/weight changes
4. Insomnia or hypersomnia
5. Psychomotor agitation or retardation
6. Fatigue or loss of energy
7. Feelings of worthlessness or excessive guilt
8. Difficulty concentrating
9. Recurrent thoughts of death or suicidal ideation

Risk Factors

• Prior history of depression or mood disorder (most significant risk)
• Discontinuing antidepressants prior to pregnancy (relapse rate 68% vs. 26% in those continuing medication)
• Single motherhood, domestic violence, low income, adolescent age
• History of depression during previous pregnancies
• Rapid postpartum hormone decline (allopregnanolone, estrogen, progesterone)

Screening

• Edinburgh Postnatal Depression Scale (EPDS) — widely validated; recommended at OB and primary care visits postpartum
• Screening recommended for all postpartum women at 6-week visit and beyond

Treatment

1. Non-pharmacological (mild-moderate PPD)

• Psychotherapy: Cognitive Behavioural Therapy (CBT) and Interpersonal Therapy (IPT) — first-line for mild cases
• Digital health interventions: meta-analyses (PMID 37330123) show benefit for postpartum depression/anxiety
• Postpartum exercise: meta-analysis (PMID 39500542) demonstrates significant reduction in depression scores
• Psychoeducation, social support, sleep hygiene

2. Pharmacological (moderate-severe PPD)

3. Novel FDA-Approved Agent: Brexanolone (Zulresso®)

• Mechanism: Positive allosteric modulator of GABA-A receptors; synthetic analogue of allopregnanolone (a progesterone metabolite that drops sharply post-delivery — implicated in PPD etiology)
• Route: Continuous IV infusion over 60 hours in an inpatient setting
• Adverse effects: Excessive sedation, sudden loss of consciousness, hypoxia — patient must be monitored continuously; supervised interaction with the baby during treatment is required
• Limitation: High cost and inpatient requirement limit broad use
• "Currently, brexanolone is the only medication specifically FDA-approved for the treatment of postpartum depression." — Goodman & Gilman's

4. Zuranolone (Zurzuvae®) — 2023 Approval

• Oral neurosteroid (GABA-A modulator), same class as brexanolone
• 14-day course taken orally — avoids inpatient requirement
• FDA-approved August 2023 for PPD

5. Role of Antidepressants During Breastfeeding

• Sertraline is the antidepressant of choice when breastfeeding — lowest relative infant dose among SSRIs
• Women who needed antidepressants during pregnancy should not discontinue postpartum; the postpartum period is high risk for relapse

Key Clinical Pearls

• Do not stop breastfeeding simply because antibiotics are needed — the vast majority are compatible, and the benefits of breastfeeding far outweigh the minor GI effects in the infant
• PPD is underdiagnosed — screen proactively with EPDS; symptoms can overlap with normal postpartum exhaustion
• Do not confuse PPD with postpartum blues (transient, resolves within 2 weeks, no treatment needed) or postpartum psychosis (rare, psychiatric emergency requiring hospitalisation)
• For women with a history of severe depression, continuing antidepressants through pregnancy and postpartum is strongly preferred over dose tapering