CFB OGPAE02-2 Physiology Of Lactation, Breast Feeding And Infant Feeding (part II)

Term vs preterm; growth parameters (weight, length, head circumference); AGA vs SGA vs LGA; symmetrical vs asymmetrical SGA; LBW ( < 2.5 kg), VLBW ( < 1.5 kg), and ELBW ( < 1 kg). ^[1]

Day 0–4: fluid loss up to 7% of birth weight. Day 5–7: starts gaining weight. Fluid requirements increase and reach 150–180 ml/kg/day by day 7. ^[1]

Why this matters: Newborns are born with excess extracellular fluid, so some early diuresis and weight loss are expected. The slide uses up to 7% as its term-infant teaching figure. Interpret the trajectory with age in hours, gestation, delivery mode, feeding effectiveness, urine/stool output, and the local newborn-weight nomogram. A loss around 10% is an assessment trigger, not a stand-alone diagnosis and not a reason to supplement automatically; rapid or excessive loss requires prompt feeding and clinical assessment. ^[10]

• Day 0: fluid needs are very low (~60 ml/kg/day for term infants)
• Fluid needs escalate daily as renal function matures and insensible losses increase
• By day 7, many neonatal fluid prescriptions reach ~150–180 ml/kg/day, but actual prescriptions are individualized for gestation, renal function, insensible losses, illness, and enteral tolerance

11 weeks: fetal swallowing starts. 24 weeks: GIT anatomically completed. 28 weeks: GIT peristalsis. 33–36 weeks: coordinated suckling and swallowing. Functional development continues into infancy — digestion and absorption. ^[1]

Why coordinated suck-swallow matters: Premature babies < 33–34 weeks cannot safely coordinate sucking, swallowing, and breathing simultaneously. This is why they require gavage (tube) feeding and why oral feeds are only introduced once this coordination develops.

1. Achieve appropriate growth and development. 2. Compensate additional demand during disease state. 3. Prevent complications of nutritional deficiency or excess. ^[1]

Positive energy balance (gain) = intake > basal + expenditure. Expenditure includes activity, thermoregulation, digestion/metabolism, fecal loss, urine, heat loss by radiation and evaporation. Requirements: protein, fat, carbohydrates, minerals, vitamins, water. ^[1]

Normal infant growth is multifactorial: gestation, age, sex, ethnicity, feeding regimen, medical conditions, and even generational factors.

Protein: Preterms need more for growth. Whey protein (~60% in breast milk, 40% casein) — soluble upon acidification, easier digestion; contains essential amino acids, immunoproteins, and enzymes. ^[1]

Fat: 40–52% daily caloric intake; at least 3% total calories from linoleic acid. LC-PUFA important for growth, brain and retinal development. ^[1]

Carbohydrates: Glycogen stores from 2nd trimester, exhausted in 12–24 hours. Normal glucose utilization rate (GUR): 4–6 mg/kg/min (term), 4–8 mg/kg/min (preterm). ^[1]

Preterms: insensible water loss, catch-up growth, inadequate nutrient storage (glycogen, fat, calcium, iron, Vit D). Disease states: higher energy requirement. Fluid restriction in RDS/chronic lung/heart failure vs liberal in sepsis/NEC/IUGR. ^[1]

Respiratory quotient (RQ) = CO₂ produced / O₂ consumed: carbohydrate (1.0), protein (~0.8), fat (~0.7). The slide proposes less carbohydrate and proportionally more fat in chronic lung disease. ^[1]

Clinical interpretation: Avoid overfeeding, which raises CO₂ production. A lower-carbohydrate, higher-fat energy distribution can reduce CO₂ generation in selected ventilatory-limited infants, but “restrict carbohydrate” is not a universal prescription: adequate glucose delivery, protein, essential fatty acids, growth, and feed tolerance still matter, and neonatal dietetic input is required.

Inborn errors of metabolism: dietary restrictions to avoid accumulation of harmful metabolites. ^[1]

Composition and volume adjusted to infants' growing needs. ^[1]

The composition of breast milk changes dynamically:

Key observations:

• Preterm milk is higher in energy, lipid, and protein than term milk — nature compensates for the premature baby's higher metabolic demands ^[1]
• Protein content decreases over the first month as growth velocity declines
• Lactose increases as the infant matures

Growth velocity and protein/fat accretion are highest at birth and decline with age. ^[1]

The stacked-bar figure separates daily weight gain into water, fat, protein, and other solids. Its central message is the falling growth velocity, not a fixed prescription:

These are approximate values read from the lecture graph, not centile cut-offs. Assess growth longitudinally with weight, length, and head circumference rather than comparing one infant with a single average.

Mature human milk vs Enfamil (cow) vs Similac (cow) vs Isomil (soy) — per 100 Cal (i.e. 150 ml of 20 Cal/oz) ^[1]

Slide-derived comparison points:

• Breast milk has the LOWEST renal solute load (14 mOsm) — gentler on immature neonatal kidneys ^[1]
• The pictured human-milk column contains little vitamin D and iron. Supplementation depends on local guidance, gestation, birth stores, diet, and risk. For example, AAP guidance gives breastfed/partly breastfed infants vitamin D 400 IU/day and provides separate iron recommendations; preterm infants require specific multivitamin and iron planning. ^[11]
• Breast milk has a higher whey:casein ratio (80:20) than cow-based formulas — whey is more digestible ^[1]
• Formula has much higher iron and Vit D because of these known deficiencies in breast milk

The slide lists lower rates of gastroenteritis, respiratory illness, UTI, NEC, childhood leukaemia, cardiovascular risk factors, ear infection, SIDS, diabetes, and atopic disease among breastfed infants. ^[1]

The slide presents an observational dose–response between breastfeeding duration and later IQ (Mortensen) and the cluster-randomized PROBIT breastfeeding-promotion trial, which found less gastrointestinal infection/eczema in infancy and higher cognitive-test scores at 6.5 years. ^[1]

How to interpret the figure: Duration–IQ curves alone cannot remove residual confounding. PROBIT randomized a promotion intervention, not breastfeeding itself, and therefore provides stronger—but still indirect—causal evidence. The safe exam phrasing is that breastfeeding is associated with modest neurodevelopmental benefit, with some supportive promotion-trial evidence.

Preterm babies need: match intrauterine growth rate (15–20 g/kg/day), higher caloric requirement, prevention of NEC. ^[1]

The balance diagram contrasts the growth nutrients in preterm formula (higher energy/protein/minerals) with the gut, immune, and bonding advantages of human milk. ^[1]

The diagram is not an either/or choice. In modern practice the usual hierarchy is:

1. Mother's own milk for preterm/LBW infants.
2. Donor human milk when mother's own milk is unavailable, where safe milk banking is available.
3. Consider multicomponent fortification for very preterm (< 32 weeks) or VLBW (< 1.5 kg) infants to meet protein/mineral needs.
4. Consider nutrient-enriched preterm formula when human milk options are unavailable or insufficient under a neonatal plan. ^[13]

Human milk in preterms provides: ↓ infection, 6.5-fold ↑ NEC in formula-fed (Lucas, Lancet 1990), protective dose > 50 ml/kg/day against late-onset sepsis, NEC prevention (Cochrane review). ^[1]

Benefits of human milk as trophic feeding: maturation/adaptation of premature GI tract, full enteral feeding achieved earlier, mothers who initiate lactation early more likely to sustain, psychological wellbeing, better neurodevelopmental outcomes (8-pt advantage at 8 years; higher visual acuity scores at 2–6 months; 5-point Bayley MDI increase per 100 ml/kg/day). ^[1]

For breastmilk-fed preterms < 1.5 kg: breastmilk fortification with human milk or formula fortifiers is recommended to optimize protein content. ^[1]

Problems: aggressive marketing + poor hospital policies. Solutions: Baby Friendly (Hospital) Initiatives. WHO International Code and national legislation. WHO/UNICEF Ten Steps to Successful Breastfeeding. ^[1]

The BFHI was launched by WHO/UNICEF in 1991 to ensure that all maternity facilities support breastfeeding. Key points:

• Hospitals should NOT distribute free formula samples (aggressive marketing from formula companies undermines breastfeeding)
• The WHO International Code of Marketing of Breast-milk Substitutes restricts formula advertising

The slide shows the older programme poster. The 2018 revised Ten Steps retain the same intent but divide it into institutional procedures (Code compliance, written policy/data monitoring, competent staff) and clinical practices (antenatal discussion, immediate skin-to-skin contact, skilled feeding support, no non-indicated supplements, rooming-in, cue-based feeding, counselling about bottles/teats/pacifiers, and coordinated follow-up). ^[14]

Historical Hong Kong discharge-rate graph

The BFHIHKA line graph rises from about 19% in 1992 to about 79% in 2010, with a plateau around the low-to-mid 60s in 2002–2006 followed by a steeper rise. It illustrates population-level change alongside hospital/policy efforts. Label it carefully: this is historical breastfeeding at maternity discharge, not current prevalence, not necessarily exclusive breastfeeding, and not duration after discharge. The two arrows in the slide are not captioned, so no specific policy event should be inferred from them.

Colostrum: contains all necessary nutrients, protects against infections, has a laxative effect, comes in small volumes. ^[1]

Why the laxative effect matters: Colostrum helps the newborn pass meconium, which contains bilirubin. Early meconium passage reduces enterohepatic circulation of bilirubin, helping to prevent neonatal jaundice.

Formula can provide regulated nutrition when needed, but it does not reproduce the full, changing cellular, immunological, hormonal, oligosaccharide, and enzyme milieu of human milk. Avoid the slide's absolute implication that formula contains “none” of any bioactive ingredient; formulations vary and may include selected added components, though they are not equivalent to the living human-milk system.

Initiate BF within 1st hour, then exclusive BF for first 6 months. On-demand feeding. No bottles, teats, or pacifiers. Infants not exclusively BF need suitable breastmilk substitutes. At around 6 months: start safe and adequate complementary foods while continuing BF for up to 2 years and beyond. ^[1]

Encourage skin contact and early feeding after delivery. Kangaroo care. Value colostrum. Avoid unnecessary supplements and discourage teats/dummies. Avoid mother-baby separation. Encourage frequent feeding. Prescribe medications with care. Be supportive. Identify and care for "at-risk" babies (neonatal hypoglycaemia). ^[1]

The kangaroo-care photographs deliberately show both a mother and a father and include a very preterm infant receiving respiratory support. The visual point is that skin-to-skin care is family-participatory care, not limited to mothers or healthy term newborns; monitoring, lines and respiratory equipment require neonatal-team coordination rather than automatically precluding it. WHO recommends kangaroo mother care routinely for preterm/LBW infants and initiation as soon as possible after birth. ^[13]

Excess lactose in stool → loose, frothy, green stools and symptoms of colic. Low fat intake → inadequate intake of fat-soluble vitamins. ^[1]

What the diagram actually shows: milk fat concentration usually rises gradually as a breast becomes less full; there is no anatomical switch that suddenly changes “foremilk” into “hindmilk.” The labels describe relative samples, not two separate kinds of milk.

Ineffective attachment and/or infrequent feeding → ↓↓↓ breast milk production → fail to sustain breastfeeding. ^[1]

Mechanism from first principles: Milk production depends substantially on effective and frequent milk removal. Prolactin supports synthesis and oxytocin drives ejection. If the baby does not attach or transfer milk well, or feeds too infrequently:

• Less nipple stimulation → less prolactin → less milk production
• Less milk removal and greater alveolar distension → local down-regulation of synthesis → further ↓ production
• This creates a vicious cycle leading to lactation failure

Effective vs ineffective attachment: ineffective attachment → nipple soreness and cracks. ^[1]

Key signs of effective attachment: baby's mouth wide open, chin touching breast, lower lip turned outward, more areola visible above than below the mouth, audible swallowing.

Jaundice → lethargy → infrequent/inefficient feeds → reduced milk intake → fewer calories/less energy → reduced gut motility → re-absorption of bilirubin → reduced breastmilk supply → MORE jaundice. ^[1]

The slide's circular graphic is important because it shows two reinforcing limbs:

Jaundice → lethargy → infrequent/ineffective feeding → ↓ intake
        ↘ ↓ milk removal → ↓ supply ↗
↓ intake → ↓ energy + ↓ gut motility → ↑ enterohepatic bilirubin reabsorption
→ more jaundice

Management: Keep mother and baby together, frequent feeds, help from lactation consultant, express breastmilk and give (if necessary), AVOID WATER. ^[1]

Causes: ineffective attachment, infrequent/restricted feeding, underlying illness. Management: exclude underlying illness, keep mother and baby together, skilled help with attachment, frequent feeds, express breastmilk, monitor I/O and weight. ^[1]

The slide labels weight, stools, urine, and feeding history as useful, and dry mouth/skin, sunken fontanelle, early serum sodium, and unsettled behaviour as “unreliable.” ^[1]

Risk factors: Prematurity, SGA, compromised states (hypothermia, asphyxia, critically ill), maternal diabetes or beta-blocker therapy. Impaired counter-regulatory response; risk of neurological impairment if prolonged. ^[1]

Care: skin contact, early and regular feeds, warmth, close monitoring, colostrum. ^[1]

Why SGA babies are at risk: They have limited glycogen and fat stores, so when the transplacental glucose supply is cut at birth, they can't mount adequate gluconeogenesis or glycogenolysis.

Why infants of diabetic mothers (IDM) are at risk: Maternal hyperglycaemia → fetal hyperinsulinaemia (islet cell hyperplasia). After birth, the glucose supply stops but the high insulin levels persist → rebound hypoglycaemia.

Reading the paired graphs: both panels are individual SGA case traces, not treatment thresholds. In the breastfed infant, glucose falls transiently while ketones rise, demonstrating an alternative-fuel response. In the formula-fed infant shown, ketones remain low despite a low early glucose. The image illustrates possible metabolic adaptation; it does not prove that a low glucose is safe, that feeding type alone caused the difference, or that ketone production replaces local screening/treatment thresholds. Symptoms, risk category, age in hours, persistence, and the validated whole-blood/plasma method determine management.

1 Energy + 33 essential nutrients. Standards: WHO CODEX Alimentarius Commission Standards (Revised 2007); HK Food and Drugs Regulation 2014. ^[1]

In Hong Kong this is not merely historical: the 2014 amendment requires infant formula to meet specified energy and nutrient-composition ranges and to carry mandatory nutrition labelling; the main infant-formula requirements have applied since December 2015. ^[15]

The slide's product examples are historical. The safe way to use the image is to identify the nutrient source and medical indication, then check the current product label; do not infer that all products in a category have identical ingredients.

Specialty formulas are medical feeds. Match the exact diagnosis and current composition with neonatal/metabolic/renal/dietetic advice; similar-looking tins are not interchangeable. ^[17][18]

Term: 110 kcal/kg/day (1st month), 95 kcal/kg/day (3–6m), 80 kcal/kg/day (6–12m). Preterm: 120 kcal/kg/day at 150 ml/kg/day. Preterm formulas: high protein, Ca, PO₄; additional Vit A, D, folate, zinc, iron; contains MCT, long-chain fats, glucose polymers, lactose. For BM-fed preterms < 1.5 kg, fortification recommended. Former preterms: enriched formula from discharge until 9–12 months corrected age. ^[1]

These are the lecturer's approximate energy targets, not a universal prescription. The maturity branch in the image should read preterm < 34 weeks and/or birth weight < 2 kg; the slide's “BW > 2 kg” is a typographical error. Current WHO guidance prioritizes mother's own milk, considers donor milk if unavailable, and conditionally considers multicomponent fortification for very preterm/VLBW infants; post-discharge enrichment is individualized rather than continued to a fixed age for every infant. ^[13]

Why MCT can help: Medium-chain fatty acids are more water-soluble and are absorbed more readily than long-chain fats, with much entering portal blood rather than chylomicrons/lymph. This can reduce dependence on bile-mediated micellar solubilization and lymphatic transport. It does not mean that all MCT behaves identically or that essential long-chain fatty acids can be omitted. Uses include:

• Cholestasis (bile salt deficiency)
• Chylothorax (lymphatic leak — LCT would worsen the chylous effusion)
• Short gut (reduced absorptive surface)

CRF/persistent hypercalcaemia: Renal formula (e.g. Similac PM 60/40) — low Ca, PO₄, K, iron. Cholestasis: MCT-enriched formula; most need fat-soluble vitamin supplementation (A, D, E, K). ^[1]

Why the pictured renal formula modifies minerals: Kidney disease can impair potassium/phosphate handling and alter calcium balance. The exact electrolyte, calcium, phosphate, protein, iron, and fluid prescription depends on the infant's disease and laboratories; “renal formula = low in everything” is unsafe shorthand.

Why fat-soluble vitamin supplementation in cholestasis: Bile salts are needed for fat-soluble vitamin absorption. In cholestasis, bile flow is impaired → malabsorption of vitamins A, D, E, K.

CMPA may be IgE- or non-IgE-mediated. Continue breastfeeding where possible; a time-limited maternal cow's-milk elimination trial is considered only when the breastfed infant has compatible symptoms, with nutritional support and planned reintroduction/challenge where safe to confirm the diagnosis. ^[1][17]

Suitable formulas:

Unsuitable formulas for CMPA:

Boil water → clean surface/wash hands → sterilized bottle → fill with HOT WATER ≥ 70°C → add correct amount of powder → gently shake → cool → test temperature (lukewarm). ^[1]

Why ≥70°C? Powdered infant formula is not sterile and can contain Cronobacter. The slide/WHO-style method adds powder to water that remains at least 70°C, then cools the sealed bottle. Follow the product and local public-health instructions because preparation advice can differ for liquid concentrate, ready-to-feed formula, and certain specialist products. For high-risk infants, sterile ready-to-feed liquid formula may be preferred when available. ^[19]

The safety details omitted from the slide:

• Measure the water first, then add the exact number of level scoops; extra powder can cause dehydration and extra water causes undernutrition/hyponatraemia.
• Prepare one feed at a time where possible and never microwave it.
• Use a started feed within 1 hour and discard leftovers; if a prepared feed will not be started immediately, refrigerate promptly and follow the local/product storage limit (CDC: within 24 hours). ^[19]

Complementary feeds "fill the gap" — BM alone insufficient to meet energy/nutritional needs. Gap widens as child grows. Slow/stop growing if gap not filled. Food types influenced by culture. By 2 years, breast milk entirely replaced by family foods. ^[1]

The energy-gap graphic shows a growing infant's total requirement rising above what milk alone can provide from about 6 months; complementary food fills the widening gap while breast milk or formula continues. The slide's statement that breast milk is “entirely replaced” by age 2 conflicts with current guidance: family foods progressively become the major nutritional source, but breastfeeding may continue to 2 years or beyond if mutually desired. ^[11][12][20]

At about 6 months, most term infants have the developmental and physiological maturity to start complementary foods. ^[1][20]

Start with 1 food item. Gradual increase in consistency and variety. 6m: pureed/mashed/semi-solid. 8m: finger foods, self-feeding. 12m: family food, mature self-feeding. ^[1]

Feeding frequency: 2–3 times/day (6–8 months), 3–4 times/day (9–24 months), +1–2 nutritious snacks/day (12–24 months). ^[1]

Alternative approaches: "baby-led weaning" — infants share family food and self-feed with hand-held foods. ^[1]

The slide's maturation/timing table can be read as a skills progression:

Do not keep an infant on smooth purées longer than necessary. Offer increasing texture and variety, energy-dense food, and iron-rich foods from the start. The reference-intake panel particularly highlights iron (11 mg/day at 7–12 months), zinc (3 mg/day), vitamin D (10 μg/400 IU/day), protein, essential fats, and total dietary diversity; these are reference values, not instructions to calculate every meal at home. Vegan feeding requires medical/dietetic supervision, especially for vitamin B12, vitamin D, iron, zinc, iodine, calcium, protein, and omega-3 fatty acids. ^[1][20]

Responsive feeding: seat the child safely, recognize hunger/satiety cues, encourage without force, minimize distraction, and assist self-feeding. The meal-frequency numbers are guides; appetite, breast/formula intake, energy density, growth, and illness modify the plan.

Allergens: do not delay common allergens simply because they are allergens. Once complementary feeding begins, introduce cooked egg and smooth peanut in age-appropriate, non-choking forms, one at a time, and keep tolerated foods in the diet. Infants with severe eczema, existing food allergy, or a previous immediate reaction need individualized advice. Whole nuts remain a choking hazard. ^[21]

Why avoid honey before 12 months: Clostridium botulinum spores can be present in honey. The infant's immature gut flora cannot outcompete these spores, leading to infant botulism — a potentially fatal flaccid paralysis.

Why avoid cow's milk as the main drink before 12 months: It is iron-poor and is not formulated to provide the complete nutrient profile of breast milk or infant formula. Pasteurized cow's milk can still be used in small amounts in cooking/foods from around 6 months, and dairy foods are not prohibited unless allergy is present.

The final slide lists growth/body composition, neurodevelopment, microbiota, infection/immune outcomes, allergy, coeliac disease, type 1 diabetes, and cardiovascular health as domains studied in relation to complementary feeding. ^[1]

These are outcome domains, not a claim that one weaning method prevents each disease. Timing, food quality and diversity, iron adequacy, texture progression, responsive feeding, and choking/food-safety precautions are the actionable takeaways.