Pregnancy

Special Nutritional Needs of Pregnancy

Nutritional Demands During Pregnancy

  • Growth of the foetus & maternal physiological changes require increased nutrients.

  • Increased energy needs particularly in the 2nd and 3rd trimesters.

  • Increased demand for specific nutrients to support foetal development, maternal health, and lactation preparation.

Gestational Weight Gain

  • Healthy range: 10-13 kg (for normal BMI).

  • Recommended weight gain varies by pre-pregnancy BMI (underweight women require more, overweight/obese women require less).

  • Excessive weight gain can lead to gestational diabetes, hypertension, and delivery complications.

  • WHO is developing global weight gain standards.

Key Nutritional Considerations

Maternal size

  • Influences placenta size

  • Placenta size determines the amount of nutrition, BW of neonate

  • Low pre-pregnant weights have lighter weighed placenta

  • Underweight mothers have higher incidence of LBW and prematurity

  • Outcome improved with extra weight gain

Periconceptual Nutrition:

  • Blood tests periconceptually - check immunity and nutrition

  • Unplanned pragancines

  • Impacts oocyte quality, implantation, and foetal programming (Barker Hypothesis).

LBW increases risk of:

  • Poor suck —> need for tube feeding from birth

  • Developmental disorders and learning outcomes

  • Long term adverse health outcomes

  • Miscarriage, neonatal death and malformations

LBW is associated with low pre-pregnant and maternal weight, poor nutrition preconception, poor gestational nutrition, inherited conditions, perinatal insults, smoking status

  • Interpret TEE with caution as women are not supposed to be in energy balance 

  • TEE and REE highly variable

Key Vitamins, Minerals & Food Sources

Iron

- RBC production, foetal growth

- Increase in maternal blood supply 

- Active bone marrow (500mg)

- Term foetus and placenta (300mg)

- Total of 800mg extra iron is needed (15mg per day)

- iron supplementation depends on iron, hB and ferritin levels before and during pregnancy                                                                                                                                                    

Zinc

- Enzyme function, foetal growth

- Required after 1st trimester

- low levels —> abnormal brain development, congenital malformations 

- Immune system, wound healing, anti-inflammatory 

- Zinc supplementation in women with low pre-pregnant weight increases infant BW

- Excess iron and dietary fibre inhibits zinc absorption

Folic acid / food folate

- DNA synthesis, neural tube development

- Demands double

- maternal erythropoiesis

- foetal and placental growth

- deficiency causes reduction in DNA synthesis and mitotic activity in individual cells

- supplementation reduces risk of neural tube defects (a month prior gestation, first few months

- all women of child bearing age should increase intakes of folate rich foods

- Low risk (0.5mg daily), high risk (5mg daily)

Iodine 

- Thyroid function, brain development

- Requirements increased substantially during pregnancy 

- Absorbed in the stomach and duodenum

- Taken up depending on supply and state of thyroid

- Iodine sufficiency in 2004 —> fortification introduced into bread making flour in 2009

- Kelp and seaweed supplements not recommended

Calcium

- Bone development, muscle function

- extra required after 12 wks for the fatal skeleton

- 30g stored in skeleton and remainder is stored for lactation

- low intakes causes ca2+ to leach from maternal skeleton —> increases risk of osteomalacia and neonatal bone density

- Ca2+ absorption inhibited by oxalates and caffeine

Vitamin D

- bone health, immune support

- only 10% from food

- sun exposure 

- dose in pregnancy supplements may be too small to correct issues of deficiency 

- supplement should be taken while breast feeding

Long chain polyunsaturated fats

- preterm birth (<37 weeks) leading cause of disability or death

- fish and fish oil associated with longer term pregnancies

- 70 RCTS, incidence of preterm and very preterm (<34 wks) was lower, fewer babies with LBW, increased pregnancies >42 weeks

Nutrient Absorption Considerations:

  • Vitamin C enhances iron absorption.

  • Excess iron & dietary fibre inhibit zinc absorption.

  • Oxalates (found in spinach) & caffeine inhibit calcium absorption

  • Avoid alcohol

  • Limit intakes of fish high in mercury (flake, swordfish)

Listeria: food borne illness

  • Soft or semi soft pasteurised white cheeses (e.g. brie, camembert, feta, blue, mozzarella, ricotta) unless thoroughly cooked

  • Unpasteurised dairy products

  • Oysters

  • Pre-packed salads

  • Soft serve ice cream

Others:

  • Raw eggs may contain Salmonella so should be avoided. Smoothies, mayonnaise or desserts like mousse may contain raw eggs

  • Hummus and tahini may contain Salmonella and should be avoided

  • Raw seed sprouts may contain E.coli, Salmonella and Listeria and should be avoided or thoroughly cooked before consumption

Common problems: morning sickness, gestational diabetes, pre-eclampsia

Nutritional Needs of Lactation

Energy requirements: Higher than pregnancy due to milk production.

  • +500 kcal/day during first 6 months.

  • +400 kcal/day after 6 months.

Protein: 67 g/day for milk production.

Calcium: 1000-1300 mg/day (prevents bone loss).

Iron: Lower than pregnancy (9-10 mg/day) due to no menstruation.

Zinc, Iodine, Magnesium, Selenium needs increase.

Hydration: Adequate fluid intake essential (~750-850 mL milk production/day).

Establishing Lactation

  • Ductal growth early in pregnancy

  • Stage 1 lactogenesis: influenced by rising levels of progesterone, prolactin and placental lactogen

  • Stage 2 lactogenesis: removal of placenta at birth triggers hormonal changes – a drop in progesterone

  • Delays due to C-section (up to 72 hours) and first delivery

  • Triggers release of colostrum – high protein, but lower fat than breastmilk, enzymes, antibodies, leukocytes, neutrophils, macrophages, probiotics

Supply 

  • Early attachment and stimulation encourages production

  • Nerve stimulation as the infant suckles stimulates release of prolactin (produces breastmilk) and oxytocin (“let-down” reflex or milk ejection reflex)

  1. Endocrine control of breastfeeding

Major mechanism to control milk production

FREQUENCY, ADEQUACY, SPACING, DURATION

As feeding is established, it moves to a supply-demand feedback system – production changes to autocrine control.

  1. Autocrine control of breastfeeding

Storage capacity of breast and amount milk taken at each feed determines the amount and rate of milk synthesis between feeds

Milk production related to degree to which the breast is emptied

SUPPLY = DEMAND

Breast Milk Composition

  • Transition milk is high in whey

  • Mature milk is more 50% whey: 50% casein (i.e. change over a year)

  • Supply responds to demand once under autonomic control

  • Within feed: fore milk higher in CHO than hind milk which is higher in fat, not emptying the breast can lead to poor infant growth 

  • Over a day: feeds earlier in day are higher in CHO

Advantages of Breastfeeding

For Mother

  • Faster uterine contraction & postpartum recovery.

  • Reduced risk of breast & ovarian cancer.

  • Helps return to pre-pregnancy weight.

  • Prolonged postpartum infertility.

  • Contributes to the economy (~$4 trillion globally).

For Infant

  • Immunity boost: Protection against diarrhoea, respiratory infections, allergies, type 1 diabetes.

  • Higher IQ & improved psychomotor development.

  • Reduced risk of obesity and chronic diseases later in life.

  • Exposure to maternal diet flavours through breast milk may influence future taste preferences.

  • In utero: flavour experience via amniotic fluid from about 30th week of gestation

  • Breast milk: cumin, vanilla, chocolate, garlic, mint, blue cheese, carrot

Breastfeeding Duration (Australia)

  • 96% of newborns receive breastmilk.

  • 51% still breastfeeding at 12 months.

  • Exclusive breastfeeding rates decline after 6 months.

Infant Formula & Its Use

Why Use Infant Formula?

  • Only recommended alternative to breastmilk.

  • All formulas must comply with Australian Food Standards Code.

  • Cannot replicate bioactive properties of breast milk (e.g., antibodies, live cells).

Component

Breast Milk

Formula

Cow's Milk

Protein

1.3 g

1.2-1.95 g

3.2 g (too high)

Fat

4.2 g

2.1-4.2 g

3.9 g

Iron

76 µg

325-975 µg

60 µg (poorly absorbed)

Calcium

35 mg

59-120 mg

120 mg (too high for infants)

Formula Variations

  • Hypoallergenic (hydrolyzed protein): For allergy-prone infants.

  • Prebiotic/probiotic formulas: Support gut health.

  • Lower protein formulas: To reduce obesity risk.

  • Soy-based formulas: For lactose-intolerant infants (must be fortified with B12 and calcium).

Why Cow’s Milk is Not Recommended (<12 months)

  • Too high in protein & sodium.

  • Low in essential fatty acids, iron, and folate.

  • Risk of iron-deficiency anaemia.

Homemade Formula Risks

  • Lacks key nutrients.

  • Can cause severe nutritional imbalances.

  • No clinical evidence supporting homemade formulas.

Best Practices for Formula Feeding

  • Correct preparation & sterilisation of bottles.

  • Proper feeding position for infant eye development.

  • Avoid overfeeding—watch for hunger/fullness cues.

  • Monitor bowel habits & growth trends.

Summary

  1. Pregnancy nutrition is crucial for maternal and infant health, influencing lifelong outcomes.

  2. Key micronutrients include iron, folate, calcium, vitamin D, iodine, and omega-3 fatty acids.

  3. Lactation increases nutritional demands for energy, protein, and specific vitamins/minerals.

  4. Breastfeeding benefits both mother and child, reducing disease risks and promoting development.

  5. Infant formula is a suitable alternative but lacks breastmilk’s immunological components.

  6. Cow’s milk and homemade formulas should be avoided due to safety concerns.