Psychology, Sociology, Anthropology and Education
Pharmacology and Toxicology: Drugs, Milk and Risk
Drug transfer and risk
Drugs enter milk mostly by passive diffusion. The milk-to-plasma ratio alone tells you little: what matters is the absolute infant dose, usually expressed as a relative infant dose (RID) - infant dose per kg divided by maternal dose per kg, times 100. An RID under about 10% is generally considered compatible. Factors that reduce transfer: high maternal protein binding, large molecular size, low oral bioavailability in the infant, short half-life. Milk is slightly more acidic than plasma, so weak bases can be "ion trapped" and concentrate.
Infant factors matter: a preterm or newborn infant clears drugs slowly, and repeated exposure accumulates.
Generally compatible: paracetamol, ibuprofen, most penicillins and cephalosporins, insulin, heparin, warfarin, sertraline and many SSRIs, most inhaled agents.
Avoid or use with specialist advice: codeine and tramadol (CYP2D6 ultrarapid metabolizers risk infant respiratory depression), radioactive iodine-131, cytotoxic chemotherapy, amiodarone, gold salts.
Galactagogues: domperidone carries QT and cardiac risk; metoclopramide can cause CNS effects in the infant; fenugreek can lower blood glucose and cross-reacts with peanut and chickpea allergy.
Alcohol: "pump and dump" is unnecessary - alcohol leaves milk as blood alcohol falls; allow about 2 hours per drink. Cannabis is not recommended (THC accumulates). Nicotine: breastfeeding remains better than not breastfeeding; support cessation.
Rule of thumb: check the RID, then ask how old and how well the infant is.
Techniques: Latch, Positions and Equipment
Latch, positions and equipment
Positioning: the infant's head and body align, ear–shoulder–hip in a line, infant held close, nose to nipple, chin leading. A good latch is asymmetric - more areola visible above the top lip than below - with a wide gape, flanged lips, and rhythmic sucking at roughly one suck per second with audible swallowing and pauses. Pain signals a shallow latch, not a need to endure.
Positions include cradle, cross-cradle, football/clutch (useful after caesarean or for twins), side-lying, and laid-back biological nurturing, which uses gravity and infant reflexes.
Hand expression: warm, gentle massage, then a C-hold behind the areola, press back toward the chest and compress, release, rotate. It is a skill every parent should leave with.
Pumps: flange fit matters - the nipple should move freely without more than 1–2 mm of areola drawn in and without rubbing; a rough guide is nipple diameter plus 4 mm. Double pumping and hands-on techniques raise yield.
Storage: freshly expressed milk at room temperature up to about 4 hours, refrigerator (≤4°C) up to about 4 days, freezer up to 6 months; thaw in the fridge and use within 24 hours; do not refreeze.
Alternatives when the breast is not available: paced bottle feeding (semi-upright, slow flow, pauses), cup, spoon, syringe and supplemental nursing systems.
Rule of thumb: pain is information - adjust the latch, do not just toughen up.