How common is down’s syndrome ( one in how many live births)
1:1000
What chromosome is tripled in Down’s Syndrome?
21st
When is the blood test for down’s syndrome in a baby taken?
15-20 weeks
At what part of the fallopian tube does fertilization normally occour?
Normally the ampule
How long does it take from fertilatizaion for the blastocyst to implant in the uterus ?
5-8 days
What happens during days 1-5 ( day 1 being fertilisation of the ovum)
The ovum progessivley divides and differentiates into a blastocysts as it moves along the fallopian tube towards the uterus
What do the (a) inner cells and (b) outer cells of the blastocyst do?
Inner cells- become embryo
Outer cells - become placenta
How does the blastocyst implant into the uterus?
The free floating blastocyst sticks to the endometrial lining and sends cords of trophoblastic cells to penetrate the endometrium
What should happen by day 12?
Blastocyst should be completely buried within the uterine lining
From what two tissues is the placenta derived from?
Trophoblast tissue
and
Decidual tissue
from what date is the placenta frist functional?
from the 5 week of pregnancy
What cells concentrate glycogen, protein and lipids for the blastocysts?
Decidual cells
How are decidual cells stimulated?
Corpus luteum secretes progesterone which stimulates decidual cells
What are the free factors which facilitate oxygen supply to the featus?
Fetal Hb has increased ability to carry O2
Fetal blood has a higher Hb concentration
Bohr Effect
What is the Bohr effect?
Fetal Hb can carry more oxygen in low pCO2 than in high pCO2
How is water transported across the placenta ?
Osmotic gradient
What does Human Chorionic Gonadotropin do during pregnancy?
Prevents involution of Corpus Luteum
(i.e stimulates the production of progesterone and oestrogen)
What does the Human Chorionic Gonadotropin over time chart look like ?
What does Human Chorionic Somatomammotropin do?
Growth hromone like effects
Decreases insulin sensitivity in mother
Ivolved in breast development
When is Human Chorionic Somatomammotropin produced?
Produce from 5 weeks of pregancy more and more each day untill birth
What are the cardiovascuar changes to the mother during pregnancy?
Cardiact output increases
Heart rate increases
Blood pressure drops during 2nd trimester
What happens to the mothers blood during pregnancy?
Plasma volume increases
consequently iron requirements increase
What does Progesterone do to the lungs?
Increases the CO2 sensitivity in respiratory centres
What happes to renal function during pregnancy?
GFR and renal plasma flow increase by up to 50%
What is pre-eclampsia ?
Pregnancy induced hypertension and proteinuria
What is eclampsia?
Extreme pre-eclampsia
Vascular spasm
Extreme hypertension
Chronic seizures
Coma
How much weight do mothers usually gain over a pregnancy?
10Kg
How much more food does a pregnant mother need per day?
250-300 extra calories per day
What iron supplements should pregnant mothers take ?
300mg ferrous sulfate
What does parturition mean?
Birth of the baby
What does oxytocin do to the uterus ?
Increases contractions and excitability
What are the three stages of labour?
1- cervical dilation
2- passage through birth canal
3- expulsion of placenta
How long is the 1st stage of labour?
8-24 hrs
What does estrogen do in terms of lactation?
Govers the growth of the ductile system
What does progesterone govern in terms of lactation?
Development of the lobule-alveolar system
Where can you get baby DNA from in order to test it ?
Placenta
Skin/unrine cells
Blood
How do you get placental cells for testing?
Chorionic villus Biopdy
How do you get baby skin/urine cells for testing?
Amniocentesis
When can a chorionic villus biopsy be preformed?
11.5 weeks
When can amniocentesis be preformed?
15 weeks onwards
When can Fetal blood sampling be done?
18 weeks +
What is the difference between mutationa and polymorphism?
Mutation causes disease whereas Polymorphisim does not
What is FISH good for?
Looking for really small chromosome changes
What does IUGR mean?
Inter uterine growth restriciton
what is the definition of preterm birth ?
birth between 24 and 36 weeks
How common are pre-term births?
6-7%
what are the survivial rates for pre term births at
24 wks
27 wks
32 wks
24wks - 25%
27wks - 80%
32 wks > 95%
What is the definition of “small for gestational age”?
Infant with a birthweight that is less than the 10th centile for gestation.
What must the bladder be like during an (a) transabominal unltrasound and (b) transvaginal ultrasound?
Transabdominal - full
Transvaginal - empty
What are the 4 common atiologys for large for dates preulgnancys?
Wrong dates
Multiple pregnancys
DIabetes
Polyhydramnios
What is Polyhydramnios?
Excess amniotic fluid
What are the symptoms of Polyhydramnios?
Discomfort
Membrane rupture
Cord Prolapse
How common are twins?
1 in 80
Regarding twins:-
What does Chorionicity mean?
What does Zygosity mean?
Chorionicty = membrane pattern of the twins
Zygosity = Number of eggs fertilised to produce twins
What is different about twins length of gestation?
Usually around 36 weeks