Nutrition in Pregnancy

• Balanced macronutrient intake gives best pregnancy outcomes
• Restrictive/fad diets should be avoided.
• Pre-pregnancy Bmi can impact on influence of gestation weight gain on pregnancy complications
• Multivitamin/mineral supplements plus folic acid recommended
• Important for healthcare providers to have time to focus on diet during pregnancy
• In preparation for pregnancy:

  • achieve and maintain healthy bodyweight
  • choose an adequate and balanced diet
  • be physically active
  • avoid harmful influences
• Other Lifestyle Risk Factors

  • BMI < 20 kg/m2 or > 30 kg/m2
  • Physical Inactivity
• Sociodemographic Risk Factors

  • Low income
  • Low educational attainment
  • Underrepresented minority race/ethnicity
• Psychosocial Risk Factors

  • depression
  • anxiety
  • stress
• Fertility outcomes

  • viable pregnancy
  • time to conception
  • spontaneous ovulation
  • semen quality (morphology, motility, concentration)
  • embryo development
  • treatment success using Assisted reproductive technologies
  • live births
• • fetal undernutrition in middle to late gestation, which leads to disproportionate fetal growth, programmes later coronary heart disease
  • early-life (in utero) events play a powerful role in influencing later susceptibility to certain chronic diseases
  • there is a link between low birth weight and increased risk of CVD, type 2 diabetes and metabolic syndrome
• • nutrition is a modifiable risk factor for infertility for both men and women
  • nutrition exerts its primary influence through the woman
• in preparation for pregnancy

  • achieve and maintain healthy bodyweight
  • choose an adequate and balanced diet
  • be physically active
  • avoid harmful influences
• Improvements in nutrition and health will contribute to better outcomes for mother and offspring
• Poor maternal nutrition status is associated with abnormal fetal growth patterns. Associated with longer term health
• Adolescent mothers are more likely to have less healthy diet
• Beneficial dietary patterns during pregnancy is related to lower risk of disorders of pregnancy
• Nutritional programming physiological processes

  • appetite and neural networks
  • metabolic pathways
  • cell structure and development
  • adipose tissue growth
  • neuroendocrine balance
  • mitochondria and endoplasmic reticulum
• Nutritional programming genomics/epigenetics

  • DNA methylation
  • histone modifications
  • RNA silencing
  • Enzymes (methylases, acetylases)
  • ncRNA/mRNA
  • polycombs
• Low birth weight (but not high birth weight) was associated with increased CVD risk. Hypothesis:

  • reduced fetal growth in which brain is spared
  • structure of fetal arteries re-distributes - permanent change in major arteries
  • reduced elasticity and raised blood pressure
  • potential link with stress response
• • critical period - time of intense development and rapid cell division
  • any adverse genetic or maternal (environmental) impact will affect developmental process
  • organ and tissues are most vulnerable to adverse influence of nutrient deficiency, nutrient excess and toxins
  • dos and don'ts during these periods need to be understood
• • the developing embryo and fetus involves many biochemical reactions, muscle growth, tissue and organ growth and metabolic activities
  • the placental development to support fetal growth requires energy and new tissue synthesis
  • breasts need to get ready for lactation for the newborn baby
• during pregnancy diet influences the health of not just one but two (or more) individuals
• On average how much weight do pregnant women put on?

  10 - 12.5 kg
• • low gestation weight gain is associated with low birth weight of the baby
  • excessive weight gain is associated with complications during pregnancy, labour and causes obesity in mother
• There is no official guidance on recommended weight gain during pregnancy in the UK.
• • increased BMR and development of maternal tissues and fetal growth demand more energy
  • dietary reference intake is not aimed at maintaining weight but to support the optimal development of maternal tissues and fetal growth and development
• • energy intake requirements during the first trimester are minimally different from requirements before pregnancy
  • during the second and third trimester, increase energy requirements by 390 - 450 kcal/day
  • recommendations +200 kcal but only for 3rd trimester
• Which nutrient is crucial during first 3 weeks of pregnancy?

  Folic acid
• • folate (synthetic form, folic acid) is a type of B vitamin present in fruits and green leafy vegetables
  • required for DNA synthesis, amino acid metabolism and methylation of genes, proteins and lipids
  • deficiency of folate may cause neural tube defects such as spina bifida, anencephaly
  • 5% of population may be deficient
  • recommendation: 400 mcg folic acid supplement while trying to get pregnant and until 12 weeks pregnant
  • difficult to reach through food alone
• Which physiological processes demand extra iron during pregnancy?

  Fetal growth and development, growth of placenta, expansion of maternal red blood cell mass, loss of blood during labour
• What pathology might occur in fetus if there is severe vitamin D deficiency in mother?

  Rickets
• • vitamin D is required for immune and nervous system function and mediates transfer of calcium from maternal stores to fetus for skeletal growth
  • babies born with features of rickets, due to vitamin D deficiency during pregnancy
  • soft weak bones, symptoms include bowed legs, stunted growth and bone pain
  • vitamin D deficiency in mothers - due to severe osteomalacia, untreated coeliac, malabsorption and pre-eclampsia
• • vitamin D is synthesised in skin when cholesterol gets converted to pre-vitamin D3 by ultraviolet rays from the sun
  • pre-vitamin D3 gets activated by the enzyme produced by liver and kidney - vitamin D - hormone
  • vitamin D maintains blood concentration of calcium and phosphorous
  • helps in calcium absorption from GI tract, reabsorption in kidneys, mobilisation from bones
• • in the UK, risk of vitamin D deficiency between October and March, with higher risk if stay indoors always and if dark skinned
  • recommended dose: all pregnant women take a daily 10 micrograms vitamin D supplement throughout pregnancy
• Which vitamin is teratogenic in excess?

  Vitamin A
• • vitamin A is an essential vitamin - must be obtained through food
  • different forms - retinal, retinol and retinoic acid (retinoid)
  • role: promoting vision, protein synthesis and cell differentiation, supporting reproduction and growth, supports immune system
  • vitamin A supports fetal growth
  • vitamin A is stored in liver and hence deficiency in UK is not common
  • recommended dose: 700 micrograms/day and excess vitamin A causes birth defects
• • pregnant women are advised not to take vitamin A supplements, cod liver oil supplements or multivitamin supplements containing vitamin A
  • liver and liver products can also be high in vitamin A and should be avoided during pregnancy
• What is the recommended intake for alcohol for adults?

  0 units
• • there is no evidence to suggest how much alcohol is safe during pregnancy
  • the safest approach is not to drink any alcohol during pregnancy
  • alcohol crosses the placenta and affects embryo and fetus
  • in the first three months it may cause miscarriage and later still birth or premature labour and low birth weight
  • alcohol consumption during later months known to cause illness during childhood and adult life