If you’re living with endometriosis, endometrium-like tissue grows outside the uterus in other areas of your pelvis — like in the bladder or ovaries.

Each month during your menstrual cycle, tissue thickens and sheds when you have your period. However, the tissue that’s inside your pelvis can’t be shed. When it swells up, it hurts — sometimes a lot.

About 1 out of every 10 women will get endometriosis at some point during their reproductive years.

Doctors don’t know what causes endometriosis for sure. Some theory believes that the tissue was there since fetal development and begins growing with puberty hormones. Others think that in some women, the tissue gets carried backward out of the uterus during their periods and then deposits in the pelvic organs.

Endometriosis can cause a lot of pain — with your period, during sex, and sometimes when you have a bowel movement. Having endometriosis can also make it harder for you to get pregnant.

Complicating matters is how long it can take to reach a correct diagnosis. Because the symptoms of endometriosis are similar to those of other conditions, some women go through years of tests before finding out they have the condition. With endometriosis, the average time from the start of symptoms to diagnosis is 6 to 10 years.

Endometriosis is often called the invisible illness because symptoms aren’t apparent to anyone except the person who has it. Your partner might not have any idea what you’re going through — unless you tell them.

Starting a conversation about your reproductive health can be difficult. You might worry that you’ll be a burden to your partner or that they won’t understand. If you’re familiar with the condition and you plan out what you’re going to say, the experience may be less intimidating for both of you.

1. Learn about endometriosis

Your partner will likely have questions about how endometriosis will affect your body or impact your relationship. To answer them accurately, you’ll want to educate yourself on the condition.

Start by talking to your doctor. Find out what treatment they recommend and how that treatment is likely to help you.

Also, ask about your outlook — including whether endometriosis might affect your fertility.

2. Choose the right time

Don’t spring the conversation on your partner. Let them know you want to talk about endometriosis and choose a time and place that works for both of you.

Make sure it’s just the two of you, and that you’re in a quiet environment free from distractions.

3. Be honest

Talk as openly as you can about your symptoms and how they might affect you both. Let your partner know that pain, fatigue, and heavy bleeding could interrupt your plans from time to time. Also, explain that sex may be painful.

Figure out ways to work around your symptoms together. For example, you might suggest doing movie nights at home instead of going out. You could also try other ways to be intimate when sex is too painful — like giving massages or gently touching one another.

4. Be supportive

When you’re experiencing pain and other symptoms of endometriosis, it’s easy to forget that your partner is living through them with you.

They may experience many of the same emotions you have — including anger, frustration, helplessness, and even despair. A study conducted on the partners of women with endometriosis found that men experienced a number of strong emotions — including anxiety, low mood, and a feeling of powerlessness.

Be sure to listen when your partner is expressing themselves. Be understanding and supportive. Of course, you should expect the same support in return.

5. Get help

If your partner isn’t coping well with your diagnosis, seek help from a professional. Go to your next doctor appointment together. Or schedule a couple’s session with a counselor — preferably one who is experienced in treating people with chronic conditions like endometriosis.

Every woman with endometriosis is different, but for some, sex is extremely painful. That pain may be due to the abnormal tissue, vaginal dryness, or hormonal changes. Whatever the cause of painful intercourse, it can disrupt your sex life and cause a major strain on your relationship.

Endometriosis pain isn’t consistent. It can get more intense at certain times of the month, or in some positions. Experiment by having sex at different times in your cycle. Incorporate other types of stimulation, like touching, massage, or oral sex. And use a lubricant to make vaginal sex more comfortable.

Open communication is especially important when you’re having sexual issues. Let your partner know how you feel, and acknowledge how they feel.

If you’re in a serious relationship and your partner wants to have children, your fertility might be a point of concern for them. Let them know that while having this condition can make it more difficult for you to conceive, treatments can improve your odds. You’ll both need to be realistic and possibly consider backup options — such as adoption.

About 176 million women around the world live with endometriosis — so you’re not alone. Once you understand your diagnosis and get started on a treatment plan, you’ll be better equipped to talk to your partner. Together, you can figure out a strategy for managing the condition as a team.