Nutrition Across the Life Cycle: Pregnancy, Infancy, Childhood and Ageing
Life-cycle items ask you to change the same nutrient prescription as physiology changes. The exam concentrates on gestational weight gain, the timing of supplementation, complementary feeding rules, and the protein, vitamin D and B12 issues of older adults.
Pregnancy and lactation
Folic acid 400 micrograms/day from at least 3 months before conception through the first trimester; women with a previous neural tube defect pregnancy need a much higher dose under medical supervision. Energy needs rise by about 300 kcal/day in the second trimester and 450 kcal/day in the third, with proportionally smaller protein increases. Iron requirement climbs steeply in the second and third trimesters, so supplementation is common where diet alone is insufficient. Gestational weight gain is BMI-specific: roughly 11-16 kg for underweight women, 8-14 kg for normal weight, 7-11 kg for overweight and 5-9 kg for obese women. Avoid alcohol, keep caffeine below 200 mg/day, avoid high-mercury fish and unpasteurised or deli foods because of listeria. Lactation adds about 500 kcal/day.
Infancy
Exclusive breastfeeding for the first 6 months, complementary foods from 6 months starting with iron-rich foods, continued breastfeeding to 2 years. No honey before 12 months because of infant botulism risk; unmodified cow milk is not the main drink before 12 months; vitamin D 400 IU/day from birth; vitamin K prophylaxis at birth.
Childhood and adolescence
Growth monitoring against age- and sex-specific curves is the core skill. Obesity prevention targets sugar-sweetened beverages, screen time and physical activity. Adolescence is the window for peak bone mass, so calcium and vitamin D intake and iron in menstruating girls deserve attention.
Ageing
Energy needs fall with loss of lean mass, but protein needs rise to 1.0-1.2 g/kg/day to counter sarcopenia. Vitamin D 600-800 IU/day, B12 for atrophic gastritis and food-cobalamin malabsorption, adequate fluid, and texture modification for dysphagia.
Worked example
A woman in her third trimester has a measured BMR of 1300 kcal and a light activity factor of 1.5: 1300 x 1.5 = 1950 kcal, plus 450 kcal for the third trimester, giving about 2400 kcal/day. If her BMI before pregnancy was 26, the gain target is 7-11 kg, so the advice is not to eat for two but to meet the added energy and protein needs while monitoring gain velocity.
Traps that cost marks
Applying a single weight-gain range to all pregnant women. Advising folic acid only after pregnancy is confirmed. Starting complementary foods before 6 months or delaying them past 6 months without iron-rich options. Applying adult BMI cut-offs to children. Recommending the same protein intake to an 80-year-old as to a 30-year-old.