Nutrition During Pregnancy

Nutrition During Pregnancy

• General Outcome: Students will become familiar with pregnancy-related physiological changes impacting nutritional needs and demonstrate their understanding of how these changes affect needs.

• Specific Outcomes:

  • Describe typical physiological changes during pregnancy.
  • Identify recommended weight gain ranges for women with various pre-pregnancy weights (underweight, normal weight, overweight, obese).
  • Identify the relationship between nutritional status during pregnancy and long-term health outcomes in offspring.

Time-related terms before, during & after pregnancy

• Periconceptional: period before conception, important for preparing for pregnancy.

• Trimester 1: weeks 0 to 12, the initial stages of pregnancy.

• Trimester 2: weeks 13 to 28, a period of significant fetal growth.

• Trimester 3: weeks 29 to 40, nearing the end of pregnancy, rapid fetal development.

• Preterm: less than 37 weeks gestation

• Postterm: greater than 42 weeks gestation

• Term: 38-42 weeks gestation

• Very preterm: less than 32 weeks gestation

• Perinatal: covers the period from 20 to 24 weeks gestation to 7 to 28 days after birth

• Neonatal: from birth to 28 days

• Post-neonatal: from 28 days to 1 year

Important Terms & Definitions

• Fetal death/Stillbirth: death of the fetus after 20 weeks of pregnancy.

• Perinatal mortality: death of fetus between 20 weeks of gestation or death of an infant during the perinatal period.

• Neonatal mortality: deaths of infants from delivery to 28 days.

• Post-neonatal mortality: deaths of infants from 28 days after birth to 1 year.

• Infant mortality: deaths of infants from birth to one year of age.

Infant Mortality

• Indicator of a country's overall health.

• Measured as the number of infant deaths per 1,000 live births.

• Decrease in infant mortality rates indicates improvements in social conditions, safe food and water supply, and disease control.

Child Mortality Rates, 1970-2019 (Malaysia)

• Infant mortality rate in Malaysia decreased from 41 deaths per 1,000 live births in 1970 to 6.9 in 2017.

• Malaysia experienced significant improvements in overall health during this period.

Causes of Infant Mortality

• Perinatal conditions.

• Pneumonia.

• Meningitis.

• Chronic lower respiratory issues.

• Congenital malformations, deformations, and chromosomal abnormalities

Maternal Mortality

• Deaths related to pregnancy or childbirth complications.

• Global maternal mortality ratio improved by 34% between 2000 and 2020.

• Most maternal deaths occur in low- and lower-middle-income countries.

• Most pregnancy-related deaths are preventable.

Causes of Maternal Mortality

• Severe bleeding (mostly postpartum).

• Infections (frequently postpartum).

• Hypertension during pregnancy (pre-eclampsia).

• Delivery complications.

• Unsafe abortions.

Physiology of Pregnancy

• Begins at conception, approximately 14 days before the next menstrual period.

• Average duration is 38 weeks (266 days), though it is often reported as 40 weeks (280 days) in healthcare, as it's measured from the first day of the last menstrual period (LMP).

• Gestational age = duration of pregnancy from conception.

• Menstrual age = time in pregnancy as calculated from the LMP

Normal Physiology Changes During Pregnancy

• Anabolic phase (first half of pregnancy): Increased food intake, lipid accumulation, elevated levels of hormones estrogen and progesterone.

• Catabolic phase (second half of pregnancy): Increased lipolysis, decreased lipoprotein lipase activity, reduced insulin sensitivity, fat redistribution.

Maternal Anabolic Phase (0-20 weeks)

• Blood volume expands; cardiac output increases.

• Fat, nutrient, and liver glycogen stores develop.

• Maternal organ growth.

• Increased appetite and food intake.

• Decreased exercise tolerance.

Maternal Catabolic Phase (20+ weeks)

• Fat and nutrient stores are mobilized.

• Blood glucose, triglycerides, and fatty acids increase.

• Fasting metabolism speeds up.

• Catabolic hormones increase.

Fetal Growth

• Roughly 10% of fetal growth happens in the first half of pregnancy; the remaining 90% occurs in the second half

Body Water Changes During Pregnancy

• Total body water increases to 7-10 liters because of increased blood, extracellular fluid, and amniotic fluid.

• Edema is common.

Hormonal Changes During Pregnancy

• Many pregnancy-related physiological changes are regulated by hormones produced in the placenta.

• hCG, estrogen, leptin, and progesterone.

Individual Hormone Functions (Pregnancy)

• hCG stimulates the corpus luteum to produce estrogen and progesterone; stimulates growth of the endometrium during pregnancy.

• hCS promotes hormonal insulin resistance in the mother to keep glucose available for the developing fetus; promotes protein synthesis and fat breakdown for maternal energy needs.

• Estrogen increases in lipid production, boosts protein synthesis and uterine blood flow, stimulates uterine and breast duct development, and increases ligament flexibility.

• Leptin regulates appetite and lipid metabolism; influences weight gain and fat utilization.

• Progesterone helps maintain the implanted embryo and relaxes uterine blood vessels and gastrointestinal tract muscles; stimulates breast development, and increases lipid storage.

Carbohydrate Metabolism

• Glucose is the favored fuel source for the developing fetus.

• Early pregnancy is associated with increased insulin production and glucose conversion into glycogen and fats.

• Late pregnancy exhibits decreased insulin sensitivity in pregnancy for fat availability for the fetus, increasing the mother's dependence on fats.

Accelerated Fasting Metabolism

• Pregnant women use stored fats for energy while sparing glucose and amino acids for the fetus.

• Prolonged fetal ketone usage can result in abnormal growth and intellectual impairment.

Protein Metabolism

• Crucial for synthesizing maternal and fetal tissues, with approximately 925 grams of protein accumulated during pregnancy.

• Maternal and fetal protein needs are met through mother's intake.

• Protein needs are met through decreased nitrogen excretion and amino acid conservation.

Fat Metabolism

• Accumulation of maternal fats in the first half of pregnancy.

• Increased fat mobilization in the second half of pregnancy.

• Dramatic increase in blood lipid levels (plasma triglycerides, cholesterol-containing lipoproteins, phospholipids, and fatty acids).

• Cholesterol and triglycerides do not promote atherosclerosis.

• Cholesterol-lowering diets can decrease maternal cholesterol levels.

Mineral Metabolism

• Maternal calcium absorption and calcium mobilization from bones increase to provide the fetus with calcium for bone development.

• Increased sodium and other mineral requirements during pregnancy.

• Low-sodium diets are not recommended.

Placenta

• Shaped like a round disk, derived from the Latin word "cake."

• Crucial for nutrient transfer, hormone production, and waste removal.

• Acts as a barrier against harmful substances.

Placenta Function

• Hormone and enzyme production.

• Nutrient and gas exchange between mother and fetus.

• Waste product removal from the fetus.

• Acts as a barrier against many harmful compounds.

Nutrient Transfer in Placenta (1)

• Placenta uses about 30-40% of the glucose supplied through the mother's circulation.

• The fetus derives water and nutrients from the amniotic fluid.

Nutrient Transfer in Placenta (2)

• Size, charge, and lipid solubility of molecules influence transfer across the placenta.

• Small molecules (water, lipids, and ketones) easily cross the placenta; other molecules such as insulin and enzymes don't easily pass.

Mechanisms of Nutrient Transport Across Placenta

• Passive diffusion.

• Facilitated diffusion (receptors/carriers on cell membranes).

• Active transport.

• Endocytosis.

Fetus is Not a Parasite

• The fetus cannot take all the nutrients it needs from the mother's body.

• Maternal insufficient nutrient intake negatively affects the fetus's growth and development more than it does the mother's well-being.

• Nutrients are initially used to support maternal needs, then for placental development.