Breastfeeding and Breast Milk: Complete Textbook Reference

1. ORGANIZATIONAL RECOMMENDATIONS

• WHO: Initiate breastfeeding within 1 hour of birth; exclusive breastfeeding for first 6 months; continue with complementary foods until 2 years or beyond
• AAP/ACOG: Exclusive breastfeeding for first 6 months, then continued through 12 months or more

2. ANATOMY AND PHYSIOLOGY OF THE BREAST

Mature Breast Anatomy

• Located in the superficial fascia between the 2nd and 6th intercostal cartilages, superficial to the pectoralis muscle
• Measures 10-12 cm in diameter, 5-7 cm central thickness
• Non-pregnant weight: ~200 g; rises to 400-600 g in pregnancy and 600-800 g during lactation
• The tail of Spence is a projection of mammary tissue into the axilla, connected to the central duct system

Development

• Ductal/lobular growth begins before puberty under estrogen and progesterone stimulation
• Alveolar bud formation begins within 1-2 years of menarche
• During pregnancy, early colostrum-like secretory material appears in acini by the 3rd month of gestation
• Prolactin stimulates colostrum secretion in the 2nd trimester; full milk production is inhibited by progesterone until placental expulsion

3. PHYSIOLOGY OF LACTATION (LACTOGENESIS)

Stages of Lactogenesis

Key Hormones

• High during pregnancy but inhibited by placenta-produced progesterone
• After delivery, suckling stimulates prolactin release from the anterior pituitary
• Prolactin levels are highest at night; suckling-induced prolactin release establishes milk supply

• Released from the posterior pituitary with suckling and conditioned stimuli
• Causes milk ejection (let-down reflex) via myoepithelial cell contraction
• The mother notices let-down as a tingling sensation in the breast or dripping from the opposite breast
• Stress, anxiety, and pain can inhibit oxytocin release

Supply and Demand

• Milk production is entirely demand-driven. Frequent, effective feeding drives greater prolactin release and milk output
• A normal feeding pattern is 8-12 feeds per 24 hours

4. COMPOSITION OF BREAST MILK

Colostrum (Days 1-4)

• Thick, yellow secretion; small volumes (initially 2-10 mL per feed)
• High in secretory IgA, lactoferrin, leukocytes, growth factors, vitamins A, E, K
• Acts as the infant's first immunization
• Lower in fat and lactose than mature milk

Transitional Milk (Days 4-10)

• Bridges colostrum and mature milk
• Rapid changes in composition over first 4 days, followed by slower changes

Mature Milk

• Calories: ~20 kcal/oz (same as standard formula)
• Carbohydrate source: Lactose (predominant)
• Protein: Whey-casein ratio favors whey (easier to digest); total protein is lower than cow's milk but highly bioavailable; kidney-appropriate amounts
• Fat: Contains cholesterol and docosahexaenoic acid (DHA), which play a role in CNS development; higher in hindmilk than foremilk

• Iron: Present in low concentration but in a highly bioavailable form (50% absorbed vs. 4-10% from formula); still insufficient for term infants after ~4 months
• Vitamin D: Present in small amounts - insufficient to prevent rickets
• Vitamin K: Low; all newborns receive IM Vitamin K at birth regardless of feeding method

Immunologic Components (>50 active factors)

• Foremilk (early in a feed) is lower in fat
• Hindmilk (later in a feed) is richer in fat and calories
• Infants should complete one breast before switching to ensure they receive hindmilk

5. BENEFITS OF BREASTFEEDING

Benefits for the Infant

• Reduced infections: Otitis media, croup, pneumonia, gastrointestinal infections, respiratory tract infections
• Reduced necrotizing enterocolitis (NEC) - especially significant in premature infants
• Reduced SIDS (sudden infant death syndrome)
• Reduced atopic conditions: Asthma, eczema
• Reduced childhood lymphoma
• Reduced type 1 and type 2 diabetes (meta-analysis evidence)
• Reduced obesity
• Cognitive benefits: Enhanced IQ scores, developmental performance, visual acuity, school performance, standardized test performance - most consistent in exclusively breastfed infants
• Reduced inflammatory bowel disease

Benefits for the Mother

• Improved postpartum recovery
• Decreased risk of postpartum hemorrhage (oxytocin-mediated uterine contraction)
• Prolonged amenorrhea (lactational amenorrhea method for contraception - <2% pregnancy risk if exclusive, amenorrheic, feeds every <4-6 hours, and <6 months postpartum)
• Psychological bonding benefits

• Reduced risk of metabolic syndrome
• Reduced risk of hypertension
• Reduced risk of type 2 diabetes mellitus
• Reduced risk of breast and ovarian cancers
• Note: Bone resorption occurs during lactation to meet calcium demands, but these losses reverse after weaning

6. INITIATION AND TECHNIQUE

Immediately After Birth

• Skin-to-skin contact immediately after delivery
• Support the mother in holding the infant at the breast and establishing a good latch
• Feed on demand whenever the infant shows early hunger signs: mouthing, rooting, increased alertness or activity (crying is a late sign of hunger)

The Latch

• Good latch: Wide-open mouth, everted lips, high position on the mother's areola
• Poor latch: Partially closed mouth, lips near the base of the nipple, little areola in the infant's mouth
• Breastfeeding should not be painful - persistent pain indicates poor latch requiring correction
• Infant uses primarily negative pressure (vacuum) via downward movement of the anterior tongue

Feeding Pattern

• Feed every 2-3 hours, or 8-12 times in 24 hours
• Offer both breasts; alternate the first breast offered at each feeding for equal stimulation
• Milk production established in first 2-4 days (colostrum); dramatic increase on day 3-5
• No need for formula supplementation unless medically indicated
• No water, glucose water, or other fluids should be given to newborns

Weight Monitoring

• Weight loss >5% in first 48 hours: assess feeding process and review outputs
• Maximum acceptable weight loss: 7% by 72 hours
• Weight should plateau at 72-96 hours and begin rising
• Birth weight should be regained by 7-10 days

Voiding/Stooling Benchmarks

• Day 1: At least 1 void, 1 stool
• Day 2: At least 2 voids, 2 stools
• Day 3+: At least 3 of each; by day 4 onwards: ≥6 voids/day
• Stool at least once daily in first month; after 3-4 months, a healthy breastfed infant may go a week without stooling (soft yellow when passed)

7. SUPPLEMENTATION REQUIREMENTS

8. DURATION AND COMPLEMENTARY FEEDING

• Exclusive breastfeeding: First 6 months (no water, juice, or other fluids)
• Complementary foods: Introduced gradually beginning around 6 months; iron-rich foods prioritized
• Continue breastfeeding: Through at least 12 months, and for as long as desired by mother and child (WHO recommends up to 2 years or beyond)

9. BREASTFEEDING DEFINITIONS (WHO Classification)

10. COMMON BREASTFEEDING PROBLEMS

Engorgement

• Breast overfilling, often in first week
• Managed by more frequent feeding, warm compresses before feeds, cold compresses after, gentle expression

Nipple Problems / Sore Nipples

• Usually caused by poor latch; most common reason for early cessation
• Breastfeeding should never be painful - always assess and correct latch
• Lanolin cream can help cracked nipples

Insufficient Milk Supply

• Most women can augment supply by: increasing feeding frequency or pumping time, adequate rest, hydration, and nutrition
• True insufficient supply is uncommon; often perceived rather than actual

Plugged Ducts

• Focal tender lump from blocked milk duct
• Treated with frequent feeding from affected side, warm compresses, gentle massage

Mastitis

• Infection (often Staphylococcus aureus) causing breast erythema, pain, warmth, flu-like symptoms
• Breastfeeding should CONTINUE through mastitis (stopping worsens milk stasis)
• Treated with antibiotics (e.g., dicloxacillin, cephalexin) and continued emptying of the breast

Candidal Infection (Thrush)

• Burning breast pain after initially pain-free feeds; may be associated with oral thrush in infant
• Treat both mother and infant simultaneously

11. CONTRAINDICATIONS TO BREASTFEEDING

Absolute Contraindications (Mother should NOT breastfeed or provide expressed milk):

• Infant classic galactosemia (requires non-lactose formula)
• HIV infection in mother (in countries recommending this - USA, Canada, UK, Italy)
• Human T-cell lymphotropic virus (HTLV-I or II) infection in mother
• Confirmed or suspected Ebola virus disease
• Untreated brucellosis in mother
• Active illicit drug use (PCP, cocaine)
• Certain chemotherapy drugs being taken by mother

Temporary Contraindications (Mother should temporarily NOT breastfeed but CAN give expressed milk):

• Active herpes simplex on the breast - may feed from unaffected breast with lesions covered; resume when lesions resolve
• Untreated active tuberculosis - may resume breastfeeding after 2 weeks of appropriate treatment and when no longer contagious
• Active varicella developing within 5 days prior to or 2 days after delivery

Temporary Contraindication to Both Breastfeeding AND Expressed Milk:

• Radioactive iodine (diagnostic/therapeutic) - pump and discard; time to resume depends on specific agent

NOT Contraindications (Safe to breastfeed):

• Hepatitis B (infant should receive HBIg and vaccine at birth)
• Hepatitis C (unless nipples are cracked and bleeding)
• Most maternal infections - diphtheria and tuberculosis are transmitted via respiratory route, not breast milk
• Cytomegalovirus (CMV) - transmission via breast milk possible but benefits outweigh risks in term infants
• Tobacco smoking - not contraindicated but strongly discouraged (increased SIDS, respiratory disease, infection risk)
• Fever alone (most causes are safe)

12. DRUGS AND BREAST MILK

Passage of Drugs into Breast Milk (Key Principles):

1. Mammary alveolar epithelium is most permeable in the early postpartum period (colostrum phase)
2. Drug excretion depends on: degree of ionization, molecular weight, fat/water solubility, and plasma:milk pH ratio (7.4:7.0)
3. Drugs enter mammary cells in their nonionized, non-protein-bound form via diffusion or active transport
4. Water-soluble drugs with molecular weight <200 pass through water-filled membrane pores
5. Most drugs appear in milk but usually do not exceed 1% of the ingested maternal dose
6. Drugs are less protein-bound in milk than in plasma
7. Drug levels in milk are independent of milk volume

Practical Guidance:

• With exception of radioactive compounds like iodine-131, no drug requires immediate breastfeeding cessation without first checking data
• For short-term medications (e.g., anesthesia), pump and discard milk for the clearance period
• Contrast agents for radiology: <1% excreted in milk, <1% of that is absorbed by infant's GI tract - breastfeeding need not be interrupted
• SSRIs: Reference LactMed database for individual agent safety profiles
• Progestin-only contraceptives (mini-pill, Depo-Provera, implants) are preferred over estrogen-containing methods during lactation; estrogen/combination products avoided before 6 weeks postpartum

Resource: LactMed (NLM/NIH) - authoritative, frequently updated drug safety database for breastfeeding mothers

13. BREASTFEEDING IN SPECIAL CIRCUMSTANCES

Preterm and NICU Infants

• Breast milk especially important - protective against NEC
• Mothers must pump and maintain supply even when infant cannot feed directly
• Preterm infants often need fortification of breast milk for adequate growth

Multiples (Twins, Triplets)

• Supply meets demand - mothers can produce sufficient milk for twins, triplets, and even quadruplets
• Twins can learn to nurse simultaneously; rotating among multiples with bottle supplementation of expressed milk is an option
• Adequate rest and household help are essential

Maternal Infections

• Not contraindicated for most infections
• Key principle: If infection is transmitted by respiratory route (e.g., TB, diphtheria), contact restrictions apply regardless of feeding route - expressed milk can still be given
• Retroviral infections (HIV) are a special case - see contraindications above
• Benefits of breastfeeding during infection include enhanced immune protection from infection-specific secretory IgA

14. THE TEN STEPS TO SUCCESSFUL BREASTFEEDING (WHO/UNICEF)

1. Comply with the International Code of Marketing of Breast-milk Substitutes
2. Have a written infant feeding policy communicated to all staff
3. Establish ongoing monitoring and data-management systems

15. CONTRACEPTION DURING BREASTFEEDING

• Lactational Amenorrhea Method (LAM): <2% pregnancy risk if ALL three conditions met: amenorrhea, fully/nearly fully breastfeeding (no gap >4-6 hours), and <6 months since delivery
• Preferred hormonal methods: Progestin-only (mini-pill, Depo-Provera, levonorgestrel implant)
• Avoid: Estrogen/combined contraceptives before 6 weeks postpartum (theoretical risk of reducing milk supply)
• At 6 weeks postpartum, combined hormonal contraception can be considered

Summary Table: Breast Milk vs. Formula

Integrated Clinical Questions on Breastfeeding

Cross-Subject Integration: Pathology, Genetics, Pharmacology, Endocrinology, Psychiatry, Surgery, Microbiology & More

SUBJECT 1: BIOCHEMISTRY & INBORN ERRORS OF METABOLISM

• Caused by deficiency of galactose-1-phosphate uridyltransferase (GALT)
• Breast milk and standard formula contain lactose → galactose → accumulates as galactose-1-phosphate → toxic to liver, brain, kidneys
• Classic galactosemia is an absolute contraindication to breastfeeding - the infant must receive a non-lactose-based (soy) formula immediately
• Even expressed breast milk is contraindicated
• Key integrative link: E. coli sepsis is a classic associated finding in galactosemic neonates - the metabolic defect impairs neutrophil function
• In milder (Duarte variant) galactosemia, partial breastfeeding may be possible (Creasy & Resnik)

• For the infant with PKU: Breastfeeding is NOT absolutely contraindicated. Breast milk is low in phenylalanine relative to formula. Carefully monitored breastfeeding with frequent phenylalanine level checks and supplementation with phenylalanine-free formula is used in many centers.
• For the mother with PKU who is pregnant: Uncontrolled maternal hyperphenylalaninemia causes fetal microcephaly, intellectual disability, and congenital heart disease (maternal PKU syndrome) - this affects the fetus via placental transfer, not via breast milk
• A mother with undiagnosed PKU should be screened if she has low intelligence of uncertain origin or family history (Creasy & Resnik)
• Key integrative point: Maternal PKU is a teratogen acting in utero; PKU in the infant is a metabolic contraindication to phenylalanine-containing feeds

SUBJECT 2: ENDOCRINOLOGY

• Severe obstetric hemorrhage → hypovolemia → ischemic necrosis of the anterior pituitary gland (which is enlarged and metabolically hyperactive during pregnancy)
• The pituitary enlarges up to 100% during pregnancy, making it vulnerable to vascular compromise
• Agalactia (inability to lactate) and amenorrhea are the cardinal postpartum signs - often the first clue to the diagnosis
• The "typical postpartum agalactia and amenorrhea may not be fully investigated at the time" (Creasy & Resnik)
• Other features: adrenal insufficiency, hypothyroidism, diabetes insipidus (hypopituitarism)
• This is an endocrine cause of complete lactation failure
• Integration: Emergency medicine perspective - Sheehan syndrome can present acutely with hypotension, adrenal crisis, or DI in the postpartum period

• Women with prolactinomas can breastfeed - prolactin is the key hormone for milk production
• Suckling-driven prolactin release is the physiologic basis of milk supply; this is preserved even with treated prolactinoma
• Tumor remission post-lactation: Two studies showed 41-68% of women with prolactinomas had remission of hyperprolactinemia after pregnancy and lactation (at a median of 22 months) - pregnancy and breastfeeding may actually benefit the tumor
• Dopamine agonists (bromocriptine, cabergoline) are used to treat prolactinoma; bromocriptine suppresses lactation (it inhibits prolactin release) - this is a key clinical question
• Physiologic hyperprolactinemia during lactation causes postpartum amenorrhea via suppression of GnRH → low LH/FSH → anovulation

• LAM has <2% failure rate ONLY when ALL 3 criteria are met simultaneously:
  1. Amenorrhea (no menstrual bleeding)
  2. Fully or nearly fully breastfeeding - no gaps >4-6 hours between feeds
  3. <6 months since most recent delivery
• If ANY criterion is not met, LAM is not reliable - at 4 months, if she began supplementing or extended night intervals, ovulation can resume
• Physiologic mechanism: Suckling → pulsatile prolactin release → inhibits GnRH pulsatility → suppresses LH/FSH → anovulation; this breaks down with infrequent feeds or supplementation
• Integration (pharmacology): Progestin-only contraceptives (mini-pill, Depo-Provera, implants) are the preferred method. Estrogen-containing products are avoided before 6 weeks postpartum (may suppress milk supply)

• Levothyroxine (T4) is compatible with breastfeeding - excreted in minimal amounts in milk
• Untreated maternal hypothyroidism reduces milk supply (thyroid hormone needed for normal lactation physiology)
• The infant's own thyroid axis matures independently; maternal T4 in milk does not suppress infant TSH
• Primary hypothyroidism is a cause of hyperprolactinemia (TRH stimulates both TSH and prolactin release) - hypothyroid women may have galactorrhea even without breastfeeding
• Integration (Pharmacology): Radioactive iodine (I-131) for thyroid cancer/hyperthyroidism is an absolute contraindication to breastfeeding (and may require weeks of milk discarding depending on dose)

SUBJECT 3: PHARMACOLOGY & TOXICOLOGY

• Lithium has a low molecular weight (MW ~7), is water-soluble, non-protein-bound, and not ionized → ideal for passage into breast milk via water-filled membrane pores
• Infant plasma lithium levels can reach 10-50% of maternal levels - significant neonatal toxicity risk (hypotonia, cyanosis, cardiac arrhythmia)
• Principles of drug passage into breast milk (Creasy & Resnik Box 11.4):
  1. Most permeable in early postpartum (colostrum phase - tight junctions between alveolar cells open)
  2. Nonionized, non-protein-bound drug passes most freely
  3. Molecular weight <200 passes via water-filled pores (favors small drugs like lithium)
  4. Most drugs reach <1% of maternal dose in milk - but lithium is an exception
  5. Mammary alveolar epithelium acts as a lipid barrier with water-filled pores
• Contrast with SSRIs: Sertraline is preferred in breastfeeding mothers with postpartum depression - it is highly protein-bound, large molecular weight, and infant plasma levels are typically undetectable

• For short-term medications (e.g., single-dose or procedural anesthesia): the mother can pump and discard milk for the clearance period, then resume
• The clearance period is typically a few hours (not days or weeks) for most anesthetic agents
• Key principle: "For medications used once or for a short time, the time required for the drug to clear the mother's system and her milk can be determined. The mother can pump and discard for that period if deemed necessary and return to breastfeeding (usually in a few hours or days, not weeks)" (Creasy & Resnik)
• Radiocontrast agents for imaging: <1% of maternal dose in milk; <1% of that is absorbed by the infant's GI tract → breastfeeding need not be interrupted
• Radioactive iodine (I-131) is the exception - requires cessation, sometimes permanently

• (a) Methotrexate - CONTRAINDICATED (antimetabolite; immunosuppressive; accumulates in infant tissues)
• (b) Sertraline - SAFE (preferred SSRI; highly protein-bound; infant levels undetectable; used for postpartum depression while breastfeeding)
• (c) Methadone - SAFE if stable opioid maintenance program and no illicit drug use (Harriet Lane, p. 769) - small amounts in milk may help prevent neonatal abstinence syndrome; buprenorphine is similar
• (d) Bromocriptine - CONTRAINDICATED (dopamine agonist; suppresses lactation by inhibiting prolactin release; used specifically to STOP milk production)
• (e) Cyclophosphamide - CONTRAINDICATED (chemotherapy; immunosuppressive; potentially carcinogenic and mutagenic to infant)

• Metoclopramide is a dopamine antagonist (anti-emetic) → blocks dopamine's inhibition of prolactin → increases prolactin levels → increases milk production
• Used off-label as a galactagogue (milk-supply enhancer) in women with insufficient supply
• Integration (endocrinology): This illustrates the dopamine-prolactin axis:
  • Dopamine (hypothalamic) normally inhibits prolactin release (prolactin-inhibiting hormone = dopamine)
  • Drugs blocking dopamine (metoclopramide, antipsychotics like haloperidol, risperidone) → hyperprolactinemia → galactorrhea
  • Dopamine agonists (bromocriptine, cabergoline) → suppress prolactin → stop lactation
• Domperidone is used similarly in some countries
• Key integrative question: A woman on haloperidol for schizophrenia develops galactorrhea - mechanism is dopamine blockade → prolactin rise

SUBJECT 4: PSYCHIATRY

• Postpartum depression (PPD) affects 10-15% of women; onset typically 2-4 weeks to 3 months postpartum
• Bidirectional relationship:
  • Prenatal and postpartum depression are associated with early cessation of breastfeeding
  • Breastfeeding challenges, pain, and worries increase risk of PPD
  • Among women without prenatal depression, high positive emotions at 2 months feeding were associated with lower depression at 2, 6, and 12 months
• Treatment: Sertraline is the preferred antidepressant during breastfeeding (Kaplan & Sadock) - a case example shows a psychiatrist recommending sertraline as "relatively safe with breastfeeding"
• Screening: Edinburgh Postnatal Depression Scale (EPDS) is the validated tool
• Integration: Oxytocin released during breastfeeding has anxiolytic and bonding effects - cessation of breastfeeding can worsen mood

• Valproate: low levels in milk; generally considered compatible with breastfeeding but monitor infant for hepatotoxicity, sedation, and thrombocytopenia
• Carbamazepine: Excreted in milk; generally considered safe; monitor for sedation and hepatic effects
• Phenobarbital: Higher levels in milk; can cause sedation and poor feeding in infant - use with caution
• Lamotrigine: Significant levels in milk (40-70% of maternal serum levels); risk of infant rash and toxicity; careful monitoring needed
• Integration (neurology - Bradley & Daroff): Women with epilepsy need seizure control throughout lactation; the risk of seizure during breastfeeding (infant dropping risk) must be weighed against drug exposure risks
• Key principle: No drug requires immediate breastfeeding cessation without first checking data; LactMed database should be consulted

SUBJECT 5: MICROBIOLOGY & INFECTIOUS DISEASE

• In developed countries (USA, Canada, UK, Italy): HIV is an absolute contraindication to breastfeeding
• Risk of HIV transmission via breastfeeding: approximately 14% (meta-analysis of 5 studies; 95% CI 7-22%) in untreated mothers (Creasy & Resnik)
• HIV has been isolated from human milk; risk is higher when mother acquires HIV during pregnancy/lactation (higher viral load)
• In developing countries (Africa): Breastfeeding is often recommended even with HIV because risk of non-HIV morbidity and mortality (diarrhea, malnutrition, infection) from not breastfeeding may outweigh HIV transmission risk. WHO Program B+ antiretroviral treatment has dramatically reduced postnatal transmission
• HIV-1 transmission via breastfeeding accounts for 15-20% of infant HIV infection in Africa
• HIV-2: Transmission via breast milk less common than HIV-1, but still contraindicated in developed countries

• If varicella develops within 5 days before or 2 days after delivery: Mother should temporarily NOT breastfeed (both direct feeding AND expressed milk are withheld)
• The infant should receive Varicella-Zoster Immune Globulin (VZIG)
• Reason: The neonate has no transplacental varicella antibodies (insufficient transfer window) and is highly susceptible to disseminated varicella
• Once the mother is no longer contagious (all lesions crusted), expressed milk may be given and breastfeeding can resume
• Contrast: If varicella develops >5 days before delivery, maternal antibodies have been transferred across the placenta - the neonate is protected, and breastfeeding is not contraindicated

• Active, untreated TB: mother should NOT breastfeed (also not give expressed milk) due to respiratory transmission risk - the restriction is about proximity, not the milk
• TB bacilli are not transmitted via breast milk (except rare cutaneous TB of the nipple/TB mastitis)
• After 2 weeks of appropriate anti-TB treatment and confirmed no longer contagious: breastfeeding CAN resume
• First-line TB drugs and breastfeeding:
  • Isoniazid, rifampicin, pyrazinamide, ethambutol: all compatible with breastfeeding in standard doses
  • Caution: Isoniazid in milk → give infant pyridoxine (Vit B6) supplementation to prevent peripheral neuropathy; if infant is also being treated for TB, caution to avoid double dosing toxicity
• Integration (pulmonology - Fishman's): "Caution should be exercised when breastfeeding newborns that are also being treated for TB, since that may increase risk of drug toxicity. Transmission of mycobacteria via breast milk is quite unlikely, except for rare cases of TB mastitis"

• Hepatitis B is NOT a contraindication to breastfeeding
• The infant must receive Hepatitis B Immunoglobulin (HBIg) AND the first dose of Hepatitis B vaccine at birth (within 12 hours)
• After this prophylaxis, the infant can be breastfed safely
• HBsAg is present in breast milk but the risk of transmission is negligible when the infant is immunized
• Contrast: Hepatitis C is also not a contraindication to breastfeeding, UNLESS the mother has cracked, bleeding nipples (blood-borne virus) - then temporary cessation is advised

• Most common organism: Staphylococcus aureus (88% of cases)
• MRSA should be considered in recurrent or treatment-resistant cases
• Management (Swanson's Family Medicine Review - clinical MCQ format):
  • Correct answer: Continue breastfeeding AND treat with hot compresses and antibiotics
  • Stopping breastfeeding worsens milk stasis → promotes abscess formation
  • Antibiotics: Dicloxacillin or cephalexin (for S. aureus); TMP-SMX if MRSA suspected
  • Analgesia: NSAIDs are compatible with breastfeeding
• Comparison table (Creasy & Resnik):

• Progression: Mastitis → abscess (in up to 10% of cases) → requires incision and drainage; do NOT stop breastfeeding from the unaffected breast
• Recurrent mastitis causes: Poor latch, inadequate emptying, nipple cracks/fissures, candidal infection, overworked/fatigued mother, infrequent feeding intervals

SUBJECT 6: SURGERY & BREAST PATHOLOGY

• A galactocele is a milk retention cyst - round, well-circumscribed, easily movable
• Occurs when a duct becomes obstructed during lactation or after feeding frequency declines
• On ultrasound/aspiration: milky fluid
• Management:
  • Aspiration confirms diagnosis and is curative in most cases
  • Surgical excision under local anesthesia without interrupting breastfeeding if cyst recurs
  • "Lactating mothers should be encouraged to continue breastfeeding" (Bailey & Love's Surgery)
• Complication: Non-resolution due to inspissated material and calcification
• Key differential (Creasy & Resnik Table 11.4):

• Breastfeeding reduces breast cancer risk by approximately 4% for every 12 months of breastfeeding (Sabiston Textbook of Surgery)
• Protective factors for ovarian cancer: >16 months of breastfeeding confers protection (Symptom to Diagnosis)
• Mechanism: Differentiation of breast epithelium, reduced estrogen exposure (amenorrhea of lactation), physical shedding of cells with potential mutations via milk
• Long-term maternal benefits also include reduced risk of: metabolic syndrome, hypertension, type 2 diabetes, and ovarian cancer
• Integration (oncology): Lack of breastfeeding is listed alongside nulliparity and late first birth as risk factors for breast cancer (Sabiston)
• BRCA mutation carriers: Breastfeeding is not contraindicated in BRCA carriers; in fact it may offer some protection in BRCA2 carriers

• Breastfeeding should NOT be stopped for investigation of a breast mass
• FNAC/core biopsy can be performed during lactation - a milk fistula is a recognized complication but is manageable
• If excision is needed, it can be done under local anesthesia without interrupting breastfeeding
• Pregnancy-associated breast cancer (PABC): Breast cancer occurring during pregnancy or within 1 year postpartum; diagnosis is often delayed because lactational changes mask malignancy
• Periductal mastitis (non-lactational): Associated with squamous metaplasia of lactiferous ducts, most common in smokers - distinct from lactational mastitis

SUBJECT 7: NEONATOLOGY & PEDIATRICS

• Robbins Pathology: "Physiologic jaundice may be exacerbated by breastfeeding due to the action of bilirubin-related compounds in milk"
• Management of hyperbilirubinemia aims to prevent bilirubin encephalopathy (kernicterus) while minimizing interference with breastfeeding (Creasy & Resnik)
• Maximum acceptable weight loss: 7% by 72 hours; birth weight regained by 7-10 days

• Challenges:
  • Hypotonia (poor sucking force and coordination)
  • Macroglossia (large tongue)
  • Flat mid-face (poor seal on areola)
  • Congenital heart disease (fatigue during feeding)
  • Hypothyroidism (common in Down syndrome; worsens feeding difficulty)
• Breast milk is strongly indicated - the immunologic benefits are especially important as Down syndrome children are more susceptible to infections and leukemia
• Special breastfeeding positions and lactation consultant support are essential
• Integration (genetics + pediatrics): Down syndrome infants may need supplemental expressed breast milk via cup feeding or tube initially; supplemental nipple shields may help

• Pierre Robin sequence (PRS): hallmark is profound micrognathia → glossoptosis (tongue falls back) → upper airway obstruction + cleft palate (ROSEN's Emergency Medicine)
• Direct breastfeeding is typically not possible - the cleft palate prevents creation of negative pressure (suction) needed for milk transfer, and micrognathia worsens the latch
• However, expressed breast milk is strongly encouraged via specialized cleft palate feeders (Haberman feeder, Pigeon bottle)
• Stickler syndrome (collagen disorder) is the most common syndrome associated with Pierre Robin sequence - also has hearing loss, joint hypermobility, myopia
• After surgical repair of cleft palate (typically 6-12 months), breastfeeding may be attempted

SUBJECT 8: NEUROLOGY

• Breastfeeding is beneficial in MS: Some evidence suggests breastfeeding prolongs the relapse-free postpartum interval (hormonal/immune effects of lactation)
• The postpartum period (first 3-6 months) carries risk of MS relapse after the protective effect of pregnancy
• Interferon-beta: Not recommended during breastfeeding (large molecular weight protein - unlikely to be absorbed by infant, but data insufficient; conservative approach is to avoid)
• Natalizumab: Excreted in milk; not recommended
• Glatiramer acetate: May be acceptable (degraded in infant GI tract)
• Bradley & Daroff: Breastfeeding section discusses medication safety in neurologic disease
• Key principle: Each drug must be individually assessed using LactMed; benefits of breastfeeding should be weighed against theoretical risks

• Valproate is excreted in breast milk (~3% of maternal dose); neonatal hepatic metabolism is immature
• Signs of valproate toxicity in infant: lethargy, poor feeding, hypotonia, elevated liver enzymes, thrombocytopenia
• Management: Check infant serum valproate level and LFTs; reduce maternal dose if possible; consider alternative AED (lamotrigine levels in milk are higher but better tolerated)
• Integration (teratology): Valproate is the most teratogenic common AED (neural tube defects, VACTERL association) - this is a prenatal issue, distinct from the breastfeeding toxicity question

SUBJECT 9: OBSTETRICS / GYNECOLOGY - SPECIAL SCENARIOS

• HTLV-1 and HTLV-2 are absolute contraindications to breastfeeding (Harriet Lane, p. 767)
• HTLV-1 is transmitted efficiently via breast milk (cell-to-cell transmission via infected lymphocytes in milk)
• HTLV-1 infection causes: Adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy (HAM/tropical spastic paraparesis)
• Freezing of breast milk kills the virus, but this is not routinely recommended; formula feeding is advised
• Contrast with HIV: Goldman-Cecil Medicine notes "HTLV-2 is detectable in breast milk" - both are retroviral and transmissible via breastfeeding

• HSV labialis (cold sore on lips): Breastfeeding is NOT contraindicated - cover the lesion, practice careful hand hygiene, avoid kissing the infant's face
• HSV lesions ON THE BREAST/NIPPLE: Breastfeeding from the affected breast is temporarily contraindicated
  • May feed from the unaffected breast (cover affected breast lesions)
  • May give expressed milk from the unaffected breast
  • Resume feeding from affected breast once lesions have fully resolved
• Neonatal HSV is a devastating infection (disseminated disease, encephalitis) - direct contact with active lesions is the primary risk, not breast milk itself

SUBJECT 10: RADIOLOGY / NUCLEAR MEDICINE

• Iodinated contrast agents: <1% of maternal dose is excreted in breast milk; <1% of that is absorbed from the infant's GI tract
• American College of Radiology position: breastfeeding does NOT need to be interrupted after iodinated contrast
• Gadolinium MRI contrast: Similarly, <0.04% excreted in milk; <1% absorbed - ACR advises breastfeeding can continue
• Radioactive iodine (I-123, diagnostic): Temporary cessation required - duration depends on agent (typically 24 hours for I-123 diagnostic scan)
• Radioactive iodine (I-131, therapeutic): Requires permanent cessation of breastfeeding in that lactation cycle; future pregnancies and breastfeeding after treatment are not affected
• Principle: "There is no drug whose possible presence in the milk would require immediate withholding of breastfeeding without first checking the data" (Creasy & Resnik) - except radioactive compounds like I-131

SUBJECT 11: FORENSIC MEDICINE / LEGAL

• Cocaine and PCP (phencyclidine): Absolute contraindication to breastfeeding (Harriet Lane; Creasy & Resnik)
• Cocaine is rapidly transferred to milk; infant develops: irritability, tremors, tachycardia, hypertension, and seizures
• Cannabis (marijuana): Also contraindicated - THC concentrates in milk (lipid-soluble, high molecular weight); associated with impaired infant neurodevelopment
• Alcohol: Not contraindicated in small amounts; limit to occasional 2 oz liquor / 8 oz wine / 2 beers for a 60 kg woman, taken >2 hours before nursing (Harriet Lane)
• Tobacco/smoking: NOT contraindicated but strongly discouraged - associated with increased SIDS, respiratory disease, and infections in exposed infants (Harriet Lane, p. 769)
• Methadone/buprenorphine: NOT contraindicated if mother is in stable maintenance program and not using illicit drugs

SUBJECT 12: SAFE HANDLING OF BREAST MILK (Milk Bank / Storage)

• Once thawed to room temperature or warmed: use within 2 hours
• Do NOT refreeze thawed breast milk
• Donor Milk Banks: Pasteurized donor human milk most commonly used in low-birth-weight infants (<1.5 kg) and those with necrotizing enterocolitis (NEC) - reduces NEC risk substantially
• Pasteurization kills most viruses including HIV, CMV, and bacteria including Mycobacterium tuberculosis

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