Endocrinology of Pregnancy Flashcards
what are the 3 key events in the ovarian cycle?
follicular growth
ovulation
luteal function
what hormone is produced by the ovum?
oestradiol
what happens in the ovum in pregnancy?
follicle releases egg which is implanted
corpus luteum develops from the remains of the follicle which has released the egg
as the egg is implanted, the corpus luteus eventually degrades once the placenta develops and takes over hormone secretion from the corpus luteum
which hormones are secreted at each stage of pregnancy?
ovum = oestradiol
corpus luteum = progesterone
HCG secreted once egg is implanted
Placenta = Human placental Lactogen (hPL), progesterone and oestrogens
what is secreted by the pituitary during pregnancy?
prolactin (lactogen)
what are the placental hormones?
Human placental lactogen (hPL)
Placental progesterone
Placental Oestrogen
how can placental hormones affect blood glucose control?
cause degree of insulin resistance to increase blood glucose so that glucose travels through placenta to give nutrition to foetus
what are the risks of placental hormones in a predisposed mother?
insulin resistance can tip over into gestational diabetes if degree of insulin resistance already present or predisposed
what 3 types of diabetes can be present in pregnancy and when do they occur?
type 1 and type 2 present before, throughout and after
gestational diabetes usually occurs in 3rd trimester and resolves after delivery
when does foetal organogenesis occur?
starts at 5 weeks
name 6 possible complications which can occur in pregnancy in mothers with pre-existing diabetes?
congenital malformation prematurity intra-uterine growth retardation (IUGR) macrosomia (large baby) polyhydramnios intra-uterine death
what is polyhydramnios?
increased fluid surrounding the baby
what 3 pregnancy complications are also risks in gestational diabetes?
macrosomnia
polyhydramnios
intra-uterine death
what complications can occur in newborn if mother has pre-existing diabetes?
respiratory distress (immature lungs) hypoglycaemia (fits)
name 3 types of congenital abnormalities which can occur if mother has diabetes
CNS defects (anencephaly, spina bifida) skeletal abnormalities (caudal regression syndrome) genital and GI (ureteric duplication)
how does maternal blood glucose affect foetal blood glucose and what 2 effects can this have?
maternal hyperglycaemia > hyperglycaemia in placenta > foetal hyperglycaemia
in 3rd trimester foetus produces its own insulin which also acts as a growth factor so foetal hyperinsulinaemia can lead to
- macrosomnia
- neonatal hypoglycaemia
how is type 1 and 2 diabetes managed during pregnancy?
pre-pregnancy counselling (enforce importance of glycaemic control)
give 5mg of folic acid (usually 400 micrograms in non-diabetic)
may need insulin as well as tablets
regular eye checks at 10/20/30 weeks gestation (accelerated retinopathy in pregnancy)
replace ACE if already taking for BP
diabetic diet
monitor HbA1c and BP
maintain BG during labour with IV insulin and dextrose
what is ACE replaced with in pregnancy?
labetalol
nifedipine
methyldopa (not first line)
what are the targets for blood glucose in pregnancy?
pre-meal = <4-5.5 mmol/L
2hr post meal = <6.5-7 mmol/L
what drug treatment is used for each type of diabetes in pregnancy?
Type 1 = continue insulin
Type 2 = Metformin, most will need insulin at some point
Gestational = lifestyle, metformin, may need insulin
when should gestational diabetes have resolved by, what happens if it doesn’t?
should resolve by 6 weeks post delivery (check via fasting BG)
if not resolved = type 2 diabetes
what are the possible implications of gestational diabetes for the mother?
50% go on to develop type 2 diabetes (higher risk if obese)
few (<5%) develop type 1
how can post gestational diabetes be prevented?
keep weight low healthy diet aerobic exercise annual fasting glucose screen metformin, acarbose, pioglitazone prophylaxis
what are the implications of thyroid disease when trying to conceive?
hypo and hyperthyroid can cause anovulatory cycles causing reduced fertility
maternal thyroxine important for neonatal CNS development
increased demand on thyroid during pregnancy
why is there increased demand on the thyroid during pregnancy?
plasma thyroid binding proteins/globulins increase so you need more thyroid hormone to keep up
how do you manage pre-existing hypothyroidism in pregnancy?
increase dose of thyroxine by 25 micrograms immediately
then increase by 50% by 20 weeks gestation
check TFTs monthly for first 20 weeks and then 2 monthly until term
- aim for TSH <3 mU/L
what are the risks of untreated hypothyroidism in pregnancy?
increased rates of
- abortion
- pre-eclampsia
- postpartum haemorrhage
- preterm labour
- reduced neuropsychological development (low IQ in baby)
what is the relationship between TSH and hCG?
hCG drives thyroid to produce thyroxine in early pregnancy (similarly to TSH)
can cause TSH suppression as not needed as much
how are thyroid function tests abnormal in pregnancy?
hCG has TSH like effect, therefore
- T4 increased
- low TSH
hCG mimics hyperthyroidism biochemically
what is hyperemesis gravidarum and what causes it?
severe nausea and vomiting in pregnancy
high hCG and many have low TSH
how can hyperemesis be distinguished from hyperthyroidism?
thyroid receptor antibodies (TRab) - negative in hyperemesis
hyperemesis resolves by 20 weeks
what are the risks of hyperthyroidism in pregnancy?
infertility spontaneous miscarriage stillbirth thyroid crisis in labour transient neonatal thyrotoxicosis
what can cause thyrotoxicosis in pregnancy?
graves disease
TMNG, toxic adenoma
thyroiditis
how is hyperthyroidism managed in pregnancy?
wait and see (hyperemesis will resolve and graves will settle)
beta blockers can help symptoms if needed
low dose anti-thyroid drugs
what anti-thyroid drugs are used in pregnancy?
1st trimester = propylthiouracil
2nd/3rd trimester = carbimazole
why must you check TRab antibodies in pregnancy and when?
check especially in 3rd trimester
can cross the placenta and cause neonatal transient hyperthyroidism
how do thyroid hormone levels change after pregnancy?
overactive at 8 weeks
underactive at 4-8 months
normal by 10-12 months
how is post partum hyperthyroidism managed?
don’t give carbimazole for overactive stage as can make following crash even worse which can cause post-partum depression
what else can cause overactive thyroid after pregnancy?
all autoimmune diseases are exacerbated again so graves disease can re-activate
