Maternal Changes In Pregnancy Flashcards
Trophoblastic invasion
During implantation and subsequent trophoblast invasion, fetal trophoblast cells and maternal uterine tissues (endometrium and myometrium) come into intimate contact with each other.
Placental hormone production
The placental hormone (Human Chorionic Gonadotropin, HCG) is present in the mother’s body during pregnancy. Its structure and effect resemble the luteinizing hormone (LH) that is secreted from the pituitary gland.
Vasodilatation
The dilatation of blood vessels, which decreases blood pressure.
Effective circulating volume - The volume of arterial blood effectively perfusing tissue.
Physiological adaptation
Internal systematic responses to external stimuli in order to help an organism maintain homeostasis.
Gestational diabetes
Any degree of glucose intolerance with onset or first recognition during pregnancy.
Pre-eclampsia
A condition in pregnancy characterized by high blood pressure, sometimes with fluid retention and proteinuria.
Maternal Changes in Pregnancy
- Major changes in multiple systems
- Causative factors
»High levels of steroids
»Mechanical displacement
»Fetal requirements - Pregnancy is a physiological event
- Systems (usually) return to normal after delivery, but not all!
Maternal system in pregnancy
- To diagnose abnormality in pregnancy need to detect changes in the changes!
- However, pregnancy may:
»exacerbate a pre-existing condition
»uncover ‘hidden’ or mild condition - Changes designed to cope with several main events:
» increase in size of the uterus
» increased metabolic requirements of uterus
» structural and metabolic requirements of fetus
» removal of fetal waste products
» provision of amniotic fluid
» preparation for delivery and puerperium
systems in which changes occur
l energy balance l respiratory system l cardiovascular system l gastrointestinal system l urinary system l endocrine system
Which hormones cause most of
the changes?
- placental peptides »hCG, hPL, GH - maternal steroids »placenta takes over ovarian (CL) production around wk 7 - placental and fetal steroids »progesterone, oestradiol, oestriol - Maternal and fetal pituitary hormones »GH, thyroid hormones, prolactin, CRF
Effects of placental steroids
lSteroids: »renin/angiotensin system »respiratory centre »GI tract »blood vessels »uterine myometrial contractility
total gain in weight 12.5-13kg
Fetus plus placenta 5 kg Fat and protein 4.5 kg Body Water (this is excluding that in other listed structures) 1.5 kg intravascular interstitial intracellular Breasts 1 kg Uterus 0.5- 1kg Ideally keep to less than 13kg: failure to gain or sudden change needs monitoring
energy balance
l need to increase energy
»output
–to cope with increased respiration and cardiac output
»and storage
–for fetus
–for labour and puerperium
l 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 Rate
l Rises by:
»350 kcal/day mid gestation 75% fetus and uterus
»250 kcal/day late gestation 25% respiration(H&L)
»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
1)1st Trimester Maternal reserves pancreatic cells increase in number plasma insulin increases fasting serum glucose decreases (laid down as stores and used by muscle)
2)2nd Trimester
Fetal reserves
hPL causes insulin resistance ie less glucose into stores=increased availability in serum glucose (morcrosses placenta) but can cause diabetes
Total Water Gain
Sodium retention,resetting of the osmostat,decrease thirst threshold,decrease in plasma oncotic pressure (albumin) E2 and P act on renin angiotensin system
diagram
Respiration:
oxygen consumption is increased
diagram
maternal blood
graph
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 hyper-coagulable=increased fibrinogen for placental separation, but increased risk of thrombosis
fetal blood
Fetal blood= increased Hb and altered it type =increased O2 binding
Oxygen given up by maternal Hb
smoking increases maternal carboxy-Hb which is more permanent and reduces the increased binding = fetal hypoxia
cardiovascular system- heart
l expanding uterus »pushes heart round »changes ECG and heart sounds l increased cardiac output »increased heart rate and stroke volume »begins as early as 3 weeks to max 40% at 28 weeks »for maternal muscle and fetal supply
cardiovascular system-
vessels
Increased cardiac output and vasodilation by steroids= Reduced peripheral resistance. Increased flow to : • uterus • placenta • muscle • kidney and • skin Neoangiogenesis....including extra capillaries in skin (spider naevi) to assist in heat loss
GI tract
diagram
Dietary supplementation…folic acid
folic acid = DNA production, growth, blood cells = uterus, placenta, fetus
supplementation advised= 5mg/ day up to week 12
Deficiency linked to spina bifida- neural tube defect
urinary system
diagrams
