What is an abnormal condition called pituitary infarction?

Loss of blood supply. Pituitary infarction is due to loss of blood supply. Sometimes the pituitary enlarges in pregnancy & after delivery the pituitary involutes & dies. Another issue can be pituitary apoplexy when a pituitary tumor outgrows its blood supply & dies with or without bleeding.
Sheehan's Syndrome. Sheehan's syndrome or pituitary infarction is rare in developed countries because of good obstetrical care. It happens after a delivery with a lot of blood loss so the pituitary gland in the brain does not get enough blood flow and part or all of it stops working. This gland supplies hormones that regulate many of the body's functions such as heart rate and metabolic rate.