Hello and welcome to the Zero to Finals podcast. My name is Tom and in this episode I'm going to be talking to you about the physiological changes that occur in pregnancy.

And you can find written notes on this topic at zero definals.com slash physiology in pregnancy or in the reproductive system section of the zero

de finals obstetrics and gynecology book. So let's get straight into it. The body goes through a large

number of changes during pregnancy and you'll come across pregnant women with a high heart rate,

low blood pressure, abnormal blood

test results and skin changes. It helps to know what changes are normal in a healthy pregnant

women and when to investigate further for underlying disease. Let's start with the hormonal

changes in pregnancy.

The anterior pituitary gland produces more adrenocortico-trophic hormone or ACTH and also produces

more prolactin and melanocyte stimulating hormone in pregnancy.

Higher ACTH levels lead to a rise in steroid hormones, particularly cortisol and aldosterone.

Higher steroid levels lead to an improvement in most autoimmune conditions such as rheumatoid arthritis

and also a susceptibility to diabetes and infections.

Increased prolactin acts to suppress FSAH and LH, leading to reduced FSAH and LH levels.

Increased melanocyte stimulating hormone causes increased pigmentation of the skin during pregnancy,

resulting in skin changes like Linnear nigra and melasma.

Remember, Linneanigra is some pigmentation underneath the umbilicus, underneath the belly button,

and melasma is increased pigmentation on the skin, usually on the

face across the cheekbones. Thyroid stimulating hormone levels remain normal, but T3 and T4 thyroid

hormones rise. HCG levels rise, roughly doubling every 48 hours, until they plateau around 8 to 12 weeks

of gestation, then they gradually start to fall. Progesterone levels rise throughout pregnancy. Progesterone

acts to maintain the pregnancy, prevent contractions and suppress the mother's immune system

...