Pregnancy Flashcards
Day 1 of the ovarian cycle is taken as…
The first day of the period
Describe phase 1 of the ovarian cycle
Follicular growth - the ovum is growing inside the follicle
Which hormone is secreted by the follicle?
Oestradiol (an oestrogen)
Secretion of which hormone peaks 1-2 days before ovulation?
Lutienising hormone (LH)
What happens to the follicle at ovulation?
The follicle releases the mature ovum and becomes the corpus luteum
At what day in the ovarian cycle does ovulation occur?
~day 14
Describe phase 2 of the ovarian cycle
Luteal function - the corpus luteum implants into the endometrial wall and secretes hormones which will thicken the endometrial wall and allow implantation of a fertilised ovum
Which hormones (2) does the corpus luteum secrete?
Progesterone (mainly)
Oestradiol (an oestrogen)
What happens to the corpus luteum of the ovum is not fertilised?
It shrinks, progesterone levels drop and the endometrial lining is shed
How long does the ovarian cycle last?
~28 days
Which hormone is detected in pregnancy tests?
hCG (human chorionic gonadotropin)
Where is hCG secreted from?
Trophoblast cells of an implanted fertilised ovum
The placenta releases which 3 hormones?
Human placental lactogen (hPL)
Placental progesterone
Placental oestrogens
What does human placental lactogen (hPL) do?
- Stimulates breast development
- Regulates metabolism of fats and carbohydrates so more glucose is free in the blood to provide energy to the foetus across the placenta
Which hormone is released by the pituitary in response to pregnancy and why?
Prolactin for breast milk production
Which 2 placental hormones can cause insulin resistance in a pregnant woman?
hPL (human placental lactogens)
Placental progesterones
How can hPL and placental progesterones lead to gestational diabetes? (2)
- Cause insulin resistance in the mother
- Raise blood glucose in the mother to provide nutrients for the foetus
At what week does foetal organogenesis occur?
~5 weeks
How can maternal hyperglycaemia lead to macrosomia (large birth weight)
Maternal hyperglycaemia leads to foetal hyperglycaemia as glucose crosses the placenta
Foetal hyperinsulinaemia occurs to combat this
Insulin is a major growth factor so leads to increased growth in the foetus
In which trimester does the foetus start producing its own insulin?
3rd trimester
How can maternal hyperglycaemia lead to neonatal hypoglycaemia at birth?
The mother’s glucose will stop crossing the placenta but foetal hyperinsulinaemia will still be occurring
This will deplete the foetus’ own supply of glucose
How does thyroid disease reduce fertility?
Causes oligo/amenorrhoea
Why is there increased demand on the thyroid during pregnancy? (2)
- Maternal thyroxine is required for foetal CNS development
- Plasma protein binding of thyroxine increases so less is free
How does the thyroid gland respond to increased demand during pregnancy?
- Increases in size
- Increases T4 production to maintain normal concentration
How does increased demand on the thyroid during pregnancy affect a woman with hypothyroidism?
The thyroid is unable to compensate for the increased demand
How is Levothyroxine (thyroxine) dose changed in a pregnant woman with hypothyroidism? (3)
- Dose increased by 25 micrograms as soon as pregnancy suspected
- Monthly thyroid function tests
- Average dose increase is by 50% by 20 weeks
What are the complications of untreated hypothyroidism in pregnancy?
- Impaired foetal neuropsychological development
- Miscarriage
- Pre-eclampsia
- Pre-term labour
- Post-partum haemorrhage
How does hCG secretion from the embryo affect thyroxine and TSH levels?
Increases thyroxine which suppresses TSH (-ve feedback)
Excess hCG in pregnancy mimics…
a) Hypothyroidism
b) Hyperthyroidism
?
Hyperthyroidism
increased T4 and decreased TSH
What symptom is strongly associated with high hCG?
Hyperemesis (vomiting)
What features make hCG-associated thyrotoxicosis more likely than hyperthyroidism?
- Raised hCG and low TSH
- Hyperemesis
- Resolves by 20 weeks gestation
Which anti-thyroid drugs can be used for hyperthyroidism in the…
-1st trimester
-2nd and 3rd trimesters
?
1st trimester: Propylthiouracil
2nd & 3rd: Carbimazole
Which antibodies can cross the placenta and cause neonatal transient hyperthyroidism?
TRAb antibodies
Describe the usual pattern of post-partum thyroiditis (3)
- Transient overactive thyroid at ~6 weeks after delivery
- Transient underactive thyroid at ~3 months after delivery
- Usually resolves at ~1 year
