Nutrition During Pregnancy Flashcards
Maternal physiology changes
Increase in maternal plasma volume (20wks)
Increase maternal nutrient stores (20wks)
Placental weight increase (31wks)
Uterine blood flow (37wks)
Foetal weight (37wks)
Maternal physiology phases of change
Maternal anabolic (1):
Blood volume expansion, increased cardiac output
Buildup of fat, nutrient and liver glycogen stores.
Growth of some maternal organs
Increased appetite (pos caloric)
Decreased exercise tolerance
Increased levels of anabolic hormones
Maternal catabolic (2):
Mobilisation of fat and nutrient stores
Increased production and blood levels of glucose, triglycerides and fatty acids, decreased liver glycogen stores
Accelerated fasting metabolism
Increased appetite fasting metabolism
Increased appetite and food intake decline somewhat near term
Increased levels of catabolic hormones
Body water changes
Increase from 7L to 10L
Results from increased blood and body tissues and extracellular volume and amniotic fluid
Oedema can occur due to an accumulation of ECF
Key placental hormones: human chorionic gonadotropin (hCG)
Maintains early pregnancy by stimulating the corpus luteum to produce oestrogen and progesterone
Stimulates growth of the endometrium
Placenta produces oestrogen and progesterone after the first 2 months of pregnancy
Key placental hormones: progesterone
Maintains implantation
Stimulates growth of the endometrium and secretion of nutrients
Relaxes smooth muscles of the uterine wall, blood vessels and GI tract
Stimulates breast development
Promotes lipid deposition
Key placental hormones: oestrogen
Increases lipid formation and storage, protein synthesis and uterine blood flow
Prompts uterine and breast duct development
Promotes ligament flexibility
Key placental hormones:human chronic somatotropin (hCS)
Increase maternal insulin resistance to maintain glucose availability for foetal use
Promotes protein synthesis and the breakdown of fat for energy for maternal use.
Can be key factor that leads to GDM
Occurs in second part of pregnancy
Key placental hormones: leptin
May participate in the regulation of appetite and lipid metabolism, weight gain and utilisation of fat stores
Carbohydrate metabolism
Early pregnancy: high oestrogen and progesterone stimulate insulin which increase glucose conversion to glycogen and fat
Late pregnancy:
Human chorionic somatotropin (hCS) and prolactin inhibit conversion of house to glycogen and fat.
Exposure to high BGL can cause neural tube defects in developing embryo; this can be caused by diabetes in the Mother. Therefore need to stress the importance of glucose monitoring in women who have had history of diabetes before or during early pregnancy.
Glucose is preferred fuel for foetus, diabetogenic effect of pregnancy results from maternal insulin resistance
Protein metabolism
Less than a kilo of protein accumulate during pregnancy
Protein and aas conserved during pregnancy.
No evidence that the body stores protein early in pregnancy
Needs (an additional 14g/d) in second and third trimester must be met by mothers intake of protein.
Need to meet all essential aas
Fat metabolism
Fat stores accumulate in first half of pregnancy, enhanced fat mobilisation in half life.
Blood lipid levels increase
Increased cholesterol is substrate for steroid hormone synthesis
Increased requirements for long chain PUFAs particularly in the third trimester to meet the demands of foetal brain and nerve tissue
Mineral metabolism
Calcium
- increased bone turnover and reformation
- not enough calcium may result in tooth loss- excessive vomiting may also impact dental
Sodium
- accumulation in mother, placenta and foetus
- restriction of sodium potentially harmful
B vitamins
- increased need due to increased metabolism of nucleus amino acids and increased DNA synthesis
The placenta
- Functions:
Hormone and enzyme production
Nutrient and gas exchange
Remove waste from foetus
-structure
Double lining of cells separating maternal and foetal blood
- nutrient transfer
Factors that affect transfer include size and charge of molecules, small molecules pass through most easily
Lipid solubility of particles
Concentration of nutrients in maternal and foetal blood
Nutrient first used for maternal needs, then placenta and then foetus. Ie if maternal nutrition is poor, greatly impacts on foetus
Occurs though passive, active and facilitated diffusion and endocytosis
Critical periods of foetal growth
Differentiation: cellular acquisition of one or more characteristics or functions different from that of the original cell
A preprogrammed time period during embryonic/foetal development when specific cells, organs and tissues are formed and integrated or functional levels established. If the mother is exposed to smoke, drugs, alcohol listeria etc during these periods, most harmful to development
Four periods:
- hyperplasia (increased cell multiplication)
- hyperplasia and hypertrophy
- hypertrophy (increased cell growth)
- maturation (stabilisation of cell no. And size)
Variation in foetal growth
Linked to energy, nutrient and oxygen availability, genetically programmed growth and development and insulin like growth factor (IGF-1) is main foetal growth stimulator Newborn weight classification: SGA- small gestational age dSGA pSGA LGA Ponders index (similar to BMI) - calculated by wt in g divided by cube of height (cms) x 100 PI for normal weight - 23-25
