Pregnancy Flashcards
Recall the time limits at which a baby is known as a zygote, blastocyst, embryo and foetus
Zygote - fertilisation to day 5
Blastocyst = days 5-9
Embryo = first 8 weeks
Foetus = thereafter
What does “conceptus” refer to?
Everything resulting from fertilised egg: Baby Placenta Foetal membranes Umbilical cord
In the UK, what is the gestational age at which an attempt at revival must be made if they are born pre-term?
24 weeks
In which trimester does the neural tube close?
1st
In the absence of an ICU cot, what is the absolute limit of gestational period for survival of a pre-term baby?
27 weeks
With an ICU cot, what is the absolute limit of gestational period for survival of a pre-term baby?
23 weeks
How many days since LMS is considered to be “term”?
280
Which gestational weeks are considered “term”?
37-41
Summarise the hormonal changes during the first trimester
hCG peaks
O,P and placental lactogen begin to increase
Why do O, P and PL levels continue to rise thorughout pregnancy?
Produced by placenta, which increases in size
Describe the levels of LH and FSH throughout pregnancy
Very low as high levels of O and P suppress the HPG axis
What is the proper name given to morning sickness?
Hyperemesis gravidarum
Recall the probably cause of hyperemesis gravidarum
hCG
Recall 2 possible mechanisms for the altered immune response in pregnancy
- Endogenous immunosuppressant production at utero-placental interface
- HLA-G expression
In which trimester is there a change in blood pressure, and in which direction does it change?
2nd
Drops significantly
Recall the 2 major maternal changes in the 3rd trimester
- Loosening of pelvic joints
2. Weight gain of 10-15kg
Recall the source of progesterone throughout pregnancy
Initially corpus luteum - hCG drives production
Lutoplacenteal shift at 8 weeks
Recall the source of oestrogen throughout pregnancy
First 8 weeks: corpus luteum
Following LPS: foetal andrenals produce DHEA, placenta converts to 17-B-oestradiol, liver converts to oestrone
Why is DHEA not produced in the placenta?
Does not express the required isoform of CYP450
To where does the placenta anchor in the uterus?
Decidua
What is the approximate surface area of the placenta?
11 m^2
How many days post-fertilisation does the blastocyst implant?
9
What is the outer later of the conceptus composed of?
Multinucleated synctiotrophoblasts
In which cells of the conceptus does the placenta develop?
Cytotrophoblasts
Describe the development of the placental blood supply during pregnancy
- Branches into villous sprouts
- Isolated from maternal blood supply by 4 weeks
- At 8 weeks: cytotrophoplast plug breakdown; spiral artery formation
- During 2nd and 3rd trimesters there is increased branching, placental diameter = 5–> 20cm
What is the gestational age limit for a foetal death to be considered “miscarriage”?
23 weeks
What is the most common cause of miscarriage?
incomplete anchrage of placenta
How is still birth risk assessed?
Foetal movement on ultrasound
