A2. Lactation, mastitis

Page created on November 22, 2021. Not updated since.



Lactation is the process of secreting milk from the breast to feed the infant. The synthesis of breast milk is induced by prolactin and ejecting of milk is induced by oxytocin.

Ideally, the infant should be exclusively breastfed in the first 6 months, followed by partial breastfeeding and partial vegetables and fruits from month 6 onwards. Breast milk contains enough energy and nutrients for the infant for the first 6 months, but after this the infant needs additional food to cover their needs. WHO recommends breastfeeding for two years or longer.

Composition of breast milk

Breast milk is composed of protein, lactose and other carbohydrates, minerals, immunoglobulins, bifidobacteria, etc. However, it does not contain sufficient amounts of vitamin D, which must be supplemented.


Colostrum is the special milk which is produced during late pregnancy and 3 – 4 days postpartum which is especially rich in protein and immunoglobulins.

Pros of breastfeeding vs formula feeding

  • Pros for the infant
    • Contains oligosaccharides which help develop a healthy intestinal bacterial flora
    • Contains IgA antibodies, complement factors, and lactoferrin (antimicrobial protein) -> passive immunity
    • Contains proteins which increase iron absorption
    • Skin-to-skin contact
    • Prevents acute infections (like otitis media, pneumonia)
    • Lower risk of asthma, allergy, obesity, diabetes mellitus, IBD
    • Better cognitive development
  • Pros for the mother
    • Faster uterus involution
    • Longer postpartum anovulation
    • Faster weight loss back to baseline
    • Lower risk of breast cancer, endometrial cancer, ovarian cancer, type 2 diabetes
    • Cheaper, more practical


There are very few absolute contraindications to breastfeeding. Maternal contraindications include HIV, active TB, and treatment with cytostatic drugs. The only infantile contraindication is galactosaemia.

Breast milk jaundice

An enzyme in milk (β-glucuronidase) increases enterohepatic recycling of bilirubin, potentially causing hyperbilirubinaemia. This is physiological and lasts for a few weeks or months. Treatment is not necessary.


Definition and epidemiology

Mastitis is the inflammation of the breast. It’s mostly a disorder of nursing mothers, and is relatively frequent, occurring in up to 10 – 20%. It mostly occurs in the first weeks after birth or at the 6-month mark.

Mastitis is usually initially inflammatory (sterile), due to interstitial oedema due to milk stasis. However, bacterial superinfection often occurs. Approx. 5 – 10% of people with mastitis go on to develop an abscess.


The causative bacterium is usually S. aureus. Bacteria enter the breast through defects in the skin, and stagnant milk provides good breeding ground for bacteria. Risk factors:

  • Insufficient emptying
  • Sore/fissured areola

Clinical features

The breast becomes tender, painful, swollen, and erythematous. Breastfeeding becomes painful. Symptoms are similar in inflammatory and bacterial mastitis, but systemic symptoms point toward bacterial mastitis.

Diagnosis and evaluation

Diagnosis is clinical. If an abscess is suspected, ultrasound may be used to diagnose it. Bacterial culture from milk or lesions may be taken.


Treatment is frequent and effective drainage of milk, analgesics, and, if bacterial etiology is suspected, antibiotics. The breast should be drained every second hour in the daytime, and at least twice during the night.

Mastitis which does not improve after frequent milk drainage is likely bacterial. Abscesses may be drained (ultrasound guided).

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