Your immune system protects your body from disease and infection. How this works is anything but simple though, and sometimes the process goes wrong.

When this happens, your immune system can attack parts of your body. This is called autoimmune disease, and it’s not simple either:

• There are more than 80 known autoimmune diseases.
• There can be overlap in the symptoms they can cause, but each disease is different.
• Two people with the same disease might have very different symptoms.
• About 80 percent of people with autoimmune disease are women.

We talked to Dr. Julianna Desmarais, a general rheumatologist who sees patients with all kinds of autoimmune diseases. She helped us unpack some of the complexity.

Why do women get autoimmune diseases more often than men?

Physicians don’t know for certain, because we don’t yet understand exactly what causes autoimmune disease. It seems to be a combination of genetics, environmental factors, and hormones, but we don’t know why some people get them and some don’t.

“Research has shown that women tend to have stronger immune systems in response to infection or vaccination than men” says Dr. Desmarais. “Autoimmune disease may be the downside of that stronger immune response.”

Why do women have stronger immune systems?

We don’t know this answer for certain either, but we do know that hormones play a role in the immune system. Women have a lot of the hormone estrogen, which seems to activate the immune system. Testosterone, which men have more of, seems to calm the immune system.

Why are women often diagnosed with autoimmune disease in early adulthood?

The answer here starts with estrogen too. Girls start to produce more estrogen as their bodies develop into adults, and this continues until they approach menopause. We think that this higher level of estrogen affects the immune system.

“That doesn’t mean that older women can’t get autoimmune disease though,” Dr. Desmarais cautions. “Rheumatoid arthritis can start later in life and there are some diseases that only start later in life.”

Which autoimmune diseases are more common in women?

• Lupus can affect the joints, skin, kidneys, heart, lungs, and other body parts.
• Graves’ disease causes the thyroid to make too much thyroid hormone.
• Hashimoto’s disease causes the thyroid to make too little thyroid hormone.
• Sjögren’s syndrome affects the glands that make moisture, like tears and saliva to cause very dry eyes and dry mouth.
• Multiple sclerosis (MS) affects the nerves, brain and spinal cord.
• Scleroderma causes abnormal hardening in the skin and blood vessels.
• Rheumatoid arthritis affects the joints and potentially other organs like the lungs.

Other autoimmune diseases you may have heard of, like psoriasis, inflammatory bowel disease (IBD), celiac disease, and type 1 diabetes, are equally common in women and men.

How do autoimmune diseases affect fertility and pregnancy?

There’s a misconception that women with certain autoimmune diseases, especially lupus, can’t or shouldn’t get pregnant.

“The truth is that even if you’re less likely to get pregnant, there is always a chance that you still can,” says Dr. Desmarais.

So if you don’t want to become pregnant, use birth control. If you do want to have a baby, planning ahead is especially important for women with autoimmune disease.

“Talk to your provider about your plans,” Dr. Desmarais says. “Some medications used to treat autoimmune disease can affect fertility or cause birth defects, so knowing your plans helps us choose how to treat you.”

Treatment that works can also make it easier to become pregnant and have a healthy baby.

“We recommend waiting to get pregnant until your disease has been quiet for at least six months,” says Dr. Desmarais.

It’s no guarantee, but in some cases pregnancy may lessen symptoms of autoimmune disease. Lupus, however, is an exception as it may flare during pregnancy.

“We think this is because your immune system calms down during pregnancy so it won’t attack your fetus,” Dr. Desmarais says. “However, it is safest and healthiest for you and your baby if your autoimmune disease is well controlled before you try to get pregnant.”

The bottom line

The most important thing to know about autoimmune diseases is that they are very individual.

“Every patient is different. Even two patients with the same diagnosis can have very different symptoms,” says Dr. Desmarais.

This means that diagnosis isn’t always easy and finding the treatment that works best for you can take time.

There aren’t any cures for autoimmune disease, but many people treated for these diseases have few or no day-to-day symptoms. There are lots of treatment options, and more are being studied all the time.

Dr. Desmarais encourages patients to work with their provider to treat their disease. “If you try one medication and it doesn’t work, try another. Don’t give up,” she says.