Endocrinology of Pregnancy

Question 1

what are the 3 key events in the ovarian cycle?

Answer 1

follicular growth
ovulation
luteal function

Question 2

what hormone is produced by the ovum?

Answer 2

oestradiol

Question 3

what happens in the ovum in pregnancy?

Answer 3

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

Question 4

which hormones are secreted at each stage of pregnancy?

Answer 4

ovum = oestradiol
corpus luteum = progesterone
HCG secreted once egg is implanted
Placenta = Human placental Lactogen (hPL), progesterone and oestrogens

Question 5

what is secreted by the pituitary during pregnancy?

Answer 5

prolactin (lactogen)

Question 6

what are the placental hormones?

Answer 6

Human placental lactogen (hPL)
Placental progesterone
Placental Oestrogen

Question 7

how can placental hormones affect blood glucose control?

Answer 7

cause degree of insulin resistance to increase blood glucose so that glucose travels through placenta to give nutrition to foetus

Question 8

what are the risks of placental hormones in a predisposed mother?

Answer 8

insulin resistance can tip over into gestational diabetes if degree of insulin resistance already present or predisposed

Question 9

what 3 types of diabetes can be present in pregnancy and when do they occur?

Answer 9

type 1 and type 2 present before, throughout and after

gestational diabetes usually occurs in 3rd trimester and resolves after delivery

Question 10

when does foetal organogenesis occur?

Answer 10

starts at 5 weeks

Question 11

name 6 possible complications which can occur in pregnancy in mothers with pre-existing diabetes?

Answer 11

congenital malformation
prematurity
intra-uterine growth retardation (IUGR)
macrosomia (large baby)
polyhydramnios
intra-uterine death

Question 12

what is polyhydramnios?

Answer 12

increased fluid surrounding the baby

Question 13

what 3 pregnancy complications are also risks in gestational diabetes?

Answer 13

macrosomnia
polyhydramnios
intra-uterine death

Question 14

what complications can occur in newborn if mother has pre-existing diabetes?

Answer 14

respiratory distress (immature lungs)
hypoglycaemia (fits)

Question 15

name 3 types of congenital abnormalities which can occur if mother has diabetes

Answer 15

CNS defects (anencephaly, spina bifida)
skeletal abnormalities (caudal regression syndrome)
genital and GI (ureteric duplication)

Question 16

how does maternal blood glucose affect foetal blood glucose and what 2 effects can this have?

Answer 16

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

Question 17

how is type 1 and 2 diabetes managed during pregnancy?

Answer 17

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

Question 18

what is ACE replaced with in pregnancy?

Answer 18

labetalol
nifedipine
methyldopa (not first line)

Question 19

what are the targets for blood glucose in pregnancy?

Answer 19

pre-meal = <4-5.5 mmol/L

2hr post meal = <6.5-7 mmol/L

Question 20

what drug treatment is used for each type of diabetes in pregnancy?

Answer 20

Type 1 = continue insulin
Type 2 = Metformin, most will need insulin at some point
Gestational = lifestyle, metformin, may need insulin

Question 21

when should gestational diabetes have resolved by, what happens if it doesn’t?

Answer 21

should resolve by 6 weeks post delivery (check via fasting BG)
if not resolved = type 2 diabetes

Question 22

what are the possible implications of gestational diabetes for the mother?

Answer 22

50% go on to develop type 2 diabetes (higher risk if obese)

few (<5%) develop type 1

Question 23

how can post gestational diabetes be prevented?

Answer 23

keep weight low
healthy diet
aerobic exercise
annual fasting glucose screen
metformin, acarbose, pioglitazone prophylaxis

Question 24

what are the implications of thyroid disease when trying to conceive?

Answer 24

hypo and hyperthyroid can cause anovulatory cycles causing reduced fertility
maternal thyroxine important for neonatal CNS development
increased demand on thyroid during pregnancy

Question 25

why is there increased demand on the thyroid during pregnancy?

Answer 25

plasma thyroid binding proteins/globulins increase so you need more thyroid hormone to keep up

Question 26

how do you manage pre-existing hypothyroidism in pregnancy?

Answer 26

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

Question 27

what are the risks of untreated hypothyroidism in pregnancy?

Answer 27

increased rates of

• abortion
• pre-eclampsia
• postpartum haemorrhage
• preterm labour
• reduced neuropsychological development (low IQ in baby)

Question 28

what is the relationship between TSH and hCG?

Answer 28

hCG drives thyroid to produce thyroxine in early pregnancy (similarly to TSH)
can cause TSH suppression as not needed as much

Question 29

how are thyroid function tests abnormal in pregnancy?

Answer 29

hCG has TSH like effect, therefore
- T4 increased
- low TSH
hCG mimics hyperthyroidism biochemically

Question 30

what is hyperemesis gravidarum and what causes it?

Answer 30

severe nausea and vomiting in pregnancy

high hCG and many have low TSH

Question 31

how can hyperemesis be distinguished from hyperthyroidism?

Answer 31

thyroid receptor antibodies (TRab) - negative in hyperemesis

hyperemesis resolves by 20 weeks

Question 32

what are the risks of hyperthyroidism in pregnancy?

Answer 32

infertility
spontaneous miscarriage
stillbirth
thyroid crisis in labour
transient neonatal thyrotoxicosis

Question 33

what can cause thyrotoxicosis in pregnancy?

Answer 33

graves disease
TMNG, toxic adenoma
thyroiditis

Question 34

how is hyperthyroidism managed in pregnancy?

Answer 34

wait and see (hyperemesis will resolve and graves will settle)
beta blockers can help symptoms if needed
low dose anti-thyroid drugs

Question 35

what anti-thyroid drugs are used in pregnancy?

Answer 35

1st trimester = propylthiouracil

2nd/3rd trimester = carbimazole

Question 36

why must you check TRab antibodies in pregnancy and when?

Answer 36

check especially in 3rd trimester

can cross the placenta and cause neonatal transient hyperthyroidism

Question 37

how do thyroid hormone levels change after pregnancy?

Answer 37

overactive at 8 weeks
underactive at 4-8 months
normal by 10-12 months

Question 38

how is post partum hyperthyroidism managed?

Answer 38

don’t give carbimazole for overactive stage as can make following crash even worse which can cause post-partum depression

Question 39

what else can cause overactive thyroid after pregnancy?

Answer 39

all autoimmune diseases are exacerbated again so graves disease can re-activate