Maternal changes in pregnancy Flashcards
Maternal system in pregnancy
• To diagnose abnormality in pregnancy need to detect changes in the changes!
• However, pregnancy may:
o exacerbate a pre-existing condition
o uncover ‘hidden’ or mild condition
Changes designed to cope with several main events
o increase in size of the uterus
o increased metabolic requirements of uterus
o structural and metabolic requirements of fetus
o removal of fetal waste products
o provision of amniotic fluid
o preparation for delivery and puerperium
Pregnancy is a
physiological event
Systems in which changes occur
- energy balance
- respiratory system
- cardiovascular system
- gastrointestinal system
- urinary system
- endocrine system
Which hormones cause most of the changes
• placental peptides o hCG, hPL, GH • maternal steroids o placenta takes over ovarian (CL) production around wk 7 • placental and fetal steroids o progesterone, oestradiol, oestriol • Maternal and fetal pituitary hormones o GH, thyroid hormones, prolactin, CRF
Effects of placental steroids
• Steroids: o renin/angiotensin system o respiratory centre o GI tract o blood vessels o uterine myometrial contractility
Total gain in weight
Fetus plus placenta 5 kg Fat and protein 4.5 kg Breasts 1 kg Uterus 0.5- 1kg Ideally keep to less than 13kg: failure to gain or sudden change needs monitoring
Energy
• need to increase energy
o output
to cope with increased respiration and cardiac output
o and storage
for fetus
for labour and puerperium
• gain in fat and protein stores 4-5 kg
increased consumption and reduced use
mainly laid down in anterior abdominal wall
utilised later in pregnancy and puerperium
Basal metabolic
• Rises by:
o 350 kcal/day mid gestation 75% fetus and uterus
o 250 kcal/day late gestation 25% respiration(H&L)
o 9 calories=1g fat therefore 40g fat for 350kcal ie 1 large Mars Bar
Glucose
- need increased availability in 2nd trimester
- active transport across placenta as fetal energy source
- fetus stores some in liver
Glucose 1st trimester
Maternal reserves pancreatic b cells increase in number plasma insulin increases fasting serum glucose decreases (laid down as stores and used by muscle)
Glucose 2nd trimester
Fetal reserves hPL causes insulin resistance ie less glucose into stores =increased availability in serum glucose (more crosses placenta) but can cause diabetes
Total water gain
\+8.51 • Placenta • Amniotic fluid • Uterine muscle • Mammary gland • Fetus • Oedema – Lungs, connective tissue, ligaments, Leakage, swollen ankles • Plasma volume – - Sodium retention, - resetting of the osmostat, - decrease thirst threshold, - decrease in plasma oncotic pressure (albumin)
Maternal blood
increased efficiency of iron absorption from gut
Haemodilution=
apparent anaemia as
concentration of Hb falls
Also changes in white cells (up) and clotting factors..blood becomes hypercoagulable=increased fibrinogen for placental separation, but increased risk of thrombosis
Fetal blood
smoking increases maternal carboxy-Hb which is more permanent and reduces the increased binding = fetal hypoxia
