Lecture 5 - Physiological Changes During Pregnancy Flashcards
What are the overall physiological changes during pregnancy?
- ↑organ weight
- ↑respiratory rate
- ↑urinary output
- ↑Heart rate and stroke volume
- ↑Blood volume and RBC
- ↑Blood lipids
- ↑Insulin resistance
- ↑BMR
- Relaxed muscle tone = fart more
What are the two phases of physiologic changes during pregnancy? Give a general overview of what happens in these phases
1) Maternal anabolic phase:0-20 weeks
- “building up” of mother’s body to supply increased needs of fetus and infant
- 10% of fetal growth occurs in this phase
- Extra build up for mom to deliver energy in next phase to fetus
2) Maternal catabolic phase: 20 weeks-birth
- 0-20 weeks to birth
- Delivering stored energy and nutrients to growing fetus
- 90% of fetal growth occurs in this phase
What happens during the maternal anabolic phase?
- Increased blood volume, growth of maternal organs
- Increased fat, glycogen, nutrient stores
- Increased appetite, decreased exercise tolerance (bc bones become more maleable)
- Increased anabolic hormones (like insulin)
What happens in the maternal catabolic phase?
- mobilization of stores
- Accelerated fasting metabolism
- Increased appetite and food intake (declines near term) and exercise tolerance
- Increased catabolic hormones
- Changes ensure readily availble nutrients to go to the placenta then transfer to the fetus
- Development of placenta is supporting these changes
What is the single best predictor of a baby’s health at birth?
- Birth weight
- Weight gain in mother is related to infant birth weight
- Lowest risk and associate problems is when there is an appropriate amount of weight gain in mother
How much should a women gain throughout pregnancy for underweight, healthy weight, overweight, and obese classifications? How much should this be per week in the second and third trimester?
- Healthy mothers should gain 11.5-16kg/25-35 pounds throughout pregnancy
- Underweight mothers should gain more! If they are underweight it is likely they are malnourished or have other social factors
- Overweight mothers should gain less over the course of their pregnancy
- Little weight gained in the first trimester. If there is weight loss it could be due to nausea or other factors
In pregnancy where does the weight go?
- Weight gain during pregnancy is mainly from the baby, extra blood/fluids/protein as well as breasts and energy stores
What weight gain is recommended during pregnancy? Why is this recommended?
- Health care professionals should recommend a weight range for all pregnant mothers and monitor
- When making recommendations they need to consider subsets of the population (such as adolescents, multiple pregnancies). Less research has been done on these populations for what is optimal, so need to follow guidelines for healthy women
- Weight gain within the guidelines is associated with the best pregnancy outcomes
- As shown with BMI it is not a one size fits all, depends on BMI
What can happen with low or excessive gestational weight gain?
- Increased risk of adverse outcomes for both mother and fetus/infant
- Fetus/Infant: low or high birth weight
- Maternal: nutritional status, gestational diabetes, pre-eclampsia (hypertension), complications during labour, post-partum weight retention
Does maternal weight gain cause fetal weight gain?
- Association between maternal weight gain and infant birth weight does NOT mean that maternal weight gain CAUSES fetal weight gain
- Fetal weight gain is compilation of many different factors - *nutrient availability, placental transfer capacity, fetal growth factors, etc.
How is energy balance maintained overall?
Energy In (Intake) = Energy Out (BMR + TEF + Physical activity)
What kind of energy balance should pregnant women have?
- Positive energy balance of ~80,000kcal during pregnancy
What is energy required for in pregnancy?
- Increases in maternal tissue
»>Breast tissue, uterine muscles, placenta, fat stores - Fetal tissues
- Energy “cost” of metabolic needs of new tissue
»>Increased BMR - Increased cost of physical activity
What are 3 possible adaptive responses to achieve positive energy balance in pregnancy?
- Increased intake
- Decreased energy expenditure
- Metabolic adaptations
All 3 occur to a varying degree in pregnancy
How does energy balance in pregnancy change for healthy weight women, underweight women, and overweight/obese women?
- Healthy weight women: BMR increases throughout pregnancy (particularly later)
- Underweight women: decreased BMR. May allow continuation of pregnancy, but compromise fetal growth
- Overweight/Obese women: greater increase in BMR (about 20%) to offset further fat accumulation
How do hormone levels change over time?
- hCG peaks early on, how you detect pregnancy
- All other hormones increase until 40 weeks
