PHY3181 Lecture Notes - Lecture 8: Herg, Perfusion, Mmp9
30 Jun 2018
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Lecture 13. Pregnancy and some its problems
Complications in pregnancy
• Labour induction = where the woman
doesn’t go into labour on time
• Miscarriage = usually occurs around 12
weeks
• Pre-eclampsia = often have to
terminate the pregnancy early (the
mum can die otherwise)
• Intra-uterine growth restriction (IUGR)
• Caesarean delivery = children will
often have immune dysfunction,
allergies, allergic reactions, childhood
leukaemia, autonomic bowel
dysfunction
• Require intervention: special care
nursery or neonatal intensive care
• Maternal obesity = often require a C
section
• Caesarean delivery in obese women
• Note that greater than 30 is
considered old to be having your first
child – increased risk in pregnancy
Problems that can arise
Fetal morbidity
• Fetal distress
• Brain damage
• Cardiovascular issues
• Perinatal mortality
Long term effects: offspring
• Cerebral palsy
• Obesity
• Hypertension
• Diabetes (type 2)
• Cognitive impairment
Maternal morbidity
• Extensive pelvic organ damage,
including hypoxic necrosis and fistula
(the pressure of the fetal head on the
rectum will start the death of the
bowel cells – this is what gives rise to a
fistula)
• Post-partum (following childbirth)
haemorrhage
• Maternal mortality
Maternal longterm effects:
• Future pregnancies – if a woman has a
C-section she is more likely to need
one on her next pregnany
• Fistula
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Loss of the baby at week 12 (first three
months/ first trimester)
UP until here everything is happening very fast.
Until 12 weeks the placenta is being formed
but it is not functional. The uterus creates
secretions these are what keeps the fetus
going. At around the 9-11 week mark, the
uterine secretions will no longer be sufficient.
The essentials of implantation
• Implantation occurs between the
uterine glands
• Initial support is predominantly from
the uterine glands
• The uterine arteries are mainly
plugged by extravillous trophoblasts
Note that the trophoblasts are the non-fetal
part of the embryo. They invade the maternal
endometrium (also called decidua)
Implantation details
During the first trimester:
• The maternal spiral artery comes up
into the decidua
• There is no blood getting into the
placenta – due to blocking
• This blocking effect is carried out by
the fetal trophoblasts which form a
plug in the spiral artery
• They eat the endothelial cells
become pseudo epithelium cells
• There is no smooth muscle left the
blood vessels cannot contract
Why we need this: when we jog, blood is
directed away from unnecessary organs eg the
reproductive system to the skeletal muscle. To
stop this from occurring we need to get rid of
the smooth muscle blood vessels cannot
contract cannot redirect the blood away
from the fetus (this is a protective mechanism
for the fetus). It is essential that the blood
vessels cannot contract cannot restrict the
placenta ensures blood supply to the
placenta.
If this eating away of the smooth muscle does
not occur you will get pre-eclampsia.
Note that there is no connection between
maternal and fetal blood (due to the immune
system). There is always some layers of cells
between the fetus and the mothers blood
supply at all stages.
At 11 weeks there is potential for a lake but
there is nothing in it as the mothers arteries
have been blocked.
This is referred to as a lake of blood. There are
no capillaries, just an endothelial layer. The
fetal vasculature dips into this pool of blood.
Note that the lake is like a tube there is no
ability to contract.
The critical period at week 12 – after plugging
especially in the centre
Oxidative stress is a significant issue
• Normal pregnancy is a state of
increased oxidative stress –
endogenous antioxidants lower
• Inflammation enhanced in normal
pregnancy enhances reaction
oxygen species production
• Endogenous protection: superoxide
dismutase (SOD), glutathione
peroxidase, catalase ect
• Protection weak in the developing
embryo, therefore it is vulnerable
• Adequate antioxidants are essential
for optimal pregnancy outcomes
At this critical point the fetus is stressed, it will
develop antioxidants the plugs will get
swept away by the mothers blood pressure
and 20% oxygen maternal blood will enter the
lake. If the antioxidants haven’t kicked in
sufficiently cannot cope with the sweeping
away of plugs. This is because the mums blood
has too much oxygen oxidative stress would
be massive (this is why the plugs are essential)
This is a critical balance of time, if something
gets out of time we get pre-eclampsia.
• Green is the placenta
• Yellow is the lake without the blood
• Top: a little bit of blood will sneak in
