Physiology of Pregnancy Flashcards
What does fertilized ovum do?
Divides progressively and differentiates into blastocyst as it moves form fertilization in upper oviduct to site of implantation in the uterus
How many days after fertilization is blastocyst transported and to where?
3-5 days
Uterus
What happens at 5-8 days post transplantation?
Attaches to lining of uterus
What do inner cells of blastocyst develop into?
Embryo
Outer cells of blastocyst develop into?
Placenta
Outer cells of blastocyst are collectively called?
Trophoblast
Placenta is derived from what?
Trophoblast and decidual tissue
What do trophoblast cells differentiate into?
Multinucleate cells which invade decidua and break down capillaries to form cavities filled with maternal blood
What week of pregnancy are foetal HR and placenta functional by?
5th week of pregnancy
PO2 maternal is higher or lower than foetal?
Higher
Is the PO2 levels maternalLY and foetally similar to CO2?
No it follows a reversed gradient
What does fetal oxygenated blood blow to the fetus in?
Via umbilical vein
Maternal oxygen poor blood flows back into which vessels?
Uterine veins
Foetal oxygen supply is facilitated by what 3 factors?
- Fetal Hb has increased ability to carry O2
- There is a higher Hb conc in fetal blood, 50% more than in adults
- Bohr effect means fetal Hb can carry more oxygen in low PCO2 than in high
Placenta transport of nutrients and waste? (water)
Water diffuses into placenta along osmotic gradient
Exchange increased during pregnancy up to 35th week (3.5L a day)
What follows H20 in placental transport?
Electrolytes (Iron and Ca2+) only go mother to child so mum must have a lot
Fetus main source of energy?
Glucose (passes the placenta via simplified transport high to low conc)
What does hCG do?
Prevents involution of corpus luteum
Effect on male testes of fetus
HCG in ectopic pregnancy?
Static or slow rising
Falling HCG levels indicate?
Failing pregnancy
Molar pregnancy HCG levels?
Very high levels
Multiple pregnancy HCG levels?
High levels
When does HCG level fall?
from 12-14 weeks
What is HPL?
Human Placental Lactogen (Human chorionic somatomammotropin)
When is HPL produced?
From week 5 of pregnancy
Effects of HCS/HPL?
Growth like effects causing protein tissue formation
Decreases insulin sensitivity in mother so more glucose for fetus
Involved in breast development
What happens with progesterone in pregnancy?
Rises from early pregnancy throughout
Involved in development of decidual cells
Decreases uterus contractility
Preparation for lactation
What happens to oestrogens throughout pregnancy?
Rise throughout pregnancy espesh estradiol
Involved in enlargement of uterus, breast development and relaxation of ligaments
Hormonal problems in pregnancy?
-Placenta produces CRH which can cause ACTH production, increased cortisol, increased aldosterone which = HT, oedema, insulin resistance and gestational diabetes
What does placenta produce and what can this cause?
HCG = N&V
HC thyrotropin= hyperthyroidism
CV changes in pregnancy?
-Increase in CO
-ECG changes, murmurs and added heart sounds= normal
CO decreases slightly in last 8 weeks
HR increases
BP drops during Tri 2
Haem changes in pregnancy?
-PV increases proportional to CO (50%) but erythropoiesis only by 25% so Hb is decreased (diluted)
Resp changes in pregnancy?
-In order to lower CO2 levels: RR increase, TV and Minute Vl increase, PCO2 decrease slightly, VC and PO2 dont change
General description of resp changes in preg?
Bigger breaths
More often
Changes in rep pregnancy are due to?
Progesterone
Enlarging uterus interfering with lung function
Urinary changes in pregnancy?
GFR and renal plasma increase up to 30-50% and peak about 16-24 weeks
Increased reabsorption of ions and water
Slight increase of urine formation
What type of coagulation state is pregnancy?
Hypercoagulable
What does pregnancy being a hypercoagulable state mean for the woman?
Reduces risk of haemorrhage during and after delivery
Does increase risk of VTE
Nutrition/metabolism in pregnancy?
200kcal extra should be ingested
30g of protein daily
Week 1-20 of pregnancy is what nutritional phase?
Mother’s anabolic phase where mother builds up fetus and only has small demands
Week 21-40 is mothers what nutritional phase?
Catabolic phase
-High demands from fetus and accelerated starvation of mother
How much acid and what type of it should pregnant mums be taking?
Folic acid
400mg 1st 12 weeks and ideally 3 months before conception
What vitamin should pregnant women take daily and how much?
Vitamin D
10mg/day
B vitamins as well to help with erythropoiesis
Common acute problems throughout pregnancy
N&V
UTI
Pain
Heartburn
Risk to foetus in 1st trimester?
Early miscarriage
Organogenesis
Teratogenic drugs
Examples of teratogenic drugs?
ACEi/ARBs Androgens Antiepileptics Cytotoxics Lithium Methotrexate Retinoids Warfarin
Risks to foetus in 2nd and 3rd trimester?
Growth of foetus
Functional development
Toxic effects on foetal tissue
