Pregnancy and Delivery Flashcards
When are the three trimesters in pregnancy and how are they defined?
3 trimesters (defined by experience rather than scientific basis)
1st – 0-13 weeks (30-60% are not successful)
2nd – 13-26 (95% pregnancies successful from here) 26 weeks earliest NATURAL survival at birth
3rd – 26-39 (39-41 weeks is term)
What major changes occur in the first trimester?
Altered immune system Altered emotional state Altered brain function Altered hormones Altered appetite – GI Imbalance
(Uterus presses on GI tract in later trimesters reducing appetite, 1st trimester instead presents with morning sickness)
What major changes occur in the second trimester?
Increased blood volume
Increased blood clotting tendency
Decreased blood pressure
Altered fluid balance
What major changes occur in the third trimester?
Altered joints (increased flexibility) Increased weight
What is the role of hCG in pregnancy? When does it peak?
HCG binds to corpus luteum mimicking LH to ensure continued release of progesterone and oestrogen.
8 Weeks peak
(Levels coincide with morning sickness)
What happens to levels of the main pregnancy hormones?
Placental lactogen - Rises continually, acts as GH for the foetal development
Oestrogens - Rises continually, becomes dominant in delivery
Progesterone - Rises continually, remains dominant until delivery
What are the terms used to describe the various stages of an unborn baby?
Conceptus – baby, placenta, foetal membrane, umbilical cord
Embryo – Baby before species distinguishable
Foetus – Baby for remainder of pregnancy
Infant – Baby after delivery
What are the different time keeping systems used in embryological development and clinical pregnancy? Why are these used?
Embryological development measured from fertilisation for accuracy.
Clinically pregnancy is measured last day of menstruation
This only becomes clinically relevant in the case of determining the actually age on infants born pre-term for likelihood of survival etc.
What are the purposes of the placenta?
Separation Exchange Biosynthesis Immunoregulation Connection
SEBIC
What are the functional subunits of the placenta? What are their features?
Functional subunit = Cotyledon
Irregular shape (Resemble gyri in brain) but often called semi-circular. Larger in centre than at periphery
Cotyledon highly branched – high surface area (11m2)
Very effective transport of molecules
What is unusual about the placental vessels? Why does this occur?
Umbilical arteries – Deoxygenated
Umbilical vein – oxygenated
(Think of the umbilical vessels like the pulmonary vessels with same set up - blood leaves the heart to be oxygenated via the mother’s oxygen supply and therefore returns oxygenated)
What is the Cytotrophoblast shell? What is its purpose?
The cytotrophoblastic shell is the external layer of cytotrophoblasts from the fetus that is found on the maternal surface of the placenta
It blocks spiral artery from placenta (if broken down
before ~8 weeks, maternal blood pressure will destroy placenta and result in miscarriage)
Limits oxygen – prevent free radical formation in early embryo
What can placental malformation result in?
Miscarriage in late 1st trimester or 2nd trimester
Pre-eclampsia (Early delivery)
Foetal growth restriction
How common are the various outcomes of pregnancy?
Miscarriage - 350k annually within 13 weeks, 7000 late miscarriages (<23 weeks)
Term (37-41 weeks) births – 700k annually
Preterm (23-37 weeks) birth – 80k annually 45k preterm labour 35k preterm emergency caesarean
(Cause of preterm emergency caesarean – Severe gestational hypertension and other life threatening conditions)
What are Braxton-Hicks contraction?
‘Practise’ contractions that may be experienced by mothers throughout pregnancy, although usually in the later trimesters. It is thought that these sporadic uterine contraction may assist the uterus in preparing for delivery.
NOT EVERY MOTHER WILL EXPERIENCE THESE
