Adrenal glands are glands that produce hormones like cortisone and aldosterone. These glands are located on top of the kidneys. The adrenal glands of someone with Addison's disease have "chronic adrenal insufficiency" and don't make enough of one or both of two hormones, either steroids hormones, corticosteriods and cortisol, or aldosterone. Underproduction of these hormones leads to Addison's disease and overproduction leads to Cushing's disease.
Only one in 100,000 people has Addison's disease, making it a rare condition and even rarer in pregnancy. Women may develop Addison's disease before pregnancy or during pregnancy. Those who have Addison's before pregnancy and are not treated have reduced fertility and are less likely to get pregnant.

Symptoms of Addison's disease

Symptoms of Addison's disease in pregnancy are not dissimilar to those outside of pregnancy and may include: 

• Muscle weakness
• Fatigue.
• Weight loss and decreased appetite.
• Inability to cope with stress
• Salt craving
• Inability to tolerate high/low temperatures
• Hypoglycemia: Low blood sugar
• Hyperpigmentation: Darkening of the skin 
• Low blood pressure, even fainting.
• Salt craving.
• Nausea, diarrhea or vomiting.

Addison's crisis

Addison's crisis is an acute and life-threatening condition of Addison's disease usually requiring hospital admission and intensive treatment. 

Cause of Addison's disease

• About 70% of Addison's disease cases result an autoimmune disease, primary adrenal insufficiency where certain proteins attack the adrenal glands. and destroys the outer layer of the glands.
• The adrenal glands can also be affected by infections.
• Cancer cells from other parts of the body to the adrenal glands can also destroy the adrenal glands
• Less common is secondary adrenal insufficiency that is caused by problems with other glands like the hypothalamus or pituitary gland, which can affect the production of hormones in the rest of the body like the adrenal glands. 
• Pituitary tumors and damage to the pituitary gland during surgery or radiation can also cause Addison's disease.
• Another cause of secondary adrenal insufficiency is prolonged or improper use of steroid hormones such as prednisone.

Pregnancy outcome and Addison's disease

According to results of a Swedish study pregnancies in women with either diagnosed or undiagnosed Addison’s disease are at increased risk for:

• preterm birth,
• low birth weight
• cesarean delivery
• other unfavorable pregnancy outcomes

Treatment of Addison's disease

Treatment of Addison's disease requires replacement of the low hormones with similar hormones like corticosteroids.