If you’ve had a cesarean section, you may be at a greater risk for complications if you later need a hysterectomy, according to a new study out today in the journal JAMA Surgery.

C-section, or the delivery of a baby via abdominal surgery, is the most common surgery in the U.S. The second most common surgery is hysterectomy, in which the uterus is removed, usually as a last resort to relieve severe pain (most commonly from uterine fibroids) or bleeding.

This new study, from researchers at Aalborg University in Denmark and Ariadne Labs (at Brigham and Women’s Hospital and the Harvard T.H. Chan School of Public Health) in Massachusetts, looked at all women in Denmark who gave birth for the first time between 1993 and 2012, and who later underwent a hysterectomy sometime between 1996 and 2012 for any reason other than cancer—7,685 women in total.

Those who gave birth vaginally had a 4.4 percent chance of needing a second surgery in the 30 days after a later hysterectomy. But those who’d had a C-section had a higher risk of needing additional surgery post-hysterectomy. After adjusting for factors such as age, income, and other medical conditions, the risk of a second surgery was 31 percent greater for women who’d had one C-section (to 6.2 percent), and 35 percent greater for women who’d had two or more (to 6.8 percent).

C-sections’ immediate risks to mothers are well understood, says Neel Shah, M.D., an assistant professor of obstetrics, gynecology, and reproductive biology at Harvard Medical School who co-wrote the new study. They include bleeding, infection, and more.

Until now, however, Shah says, “we haven’t had a lot of information of what the long-term effects are on the mom.”

Here’s what you need to know about this new research on hysterectomy complications and what you can do to lower your odds of having a C-section in the first place.

Surgery Complications and C-Sections

In general, it’s rare for women to women to need a second surgery after a hysterectomy. But when it happens, Shah says, “It’s one signal that something didn’t go as planned during the original operation.”

For instance, a surgeon might have inadvertently damaged another organ, such as the bowel, during the surgery. Or the woman might develop an infection in her abdomen shortly after the surgery.

According to Shah, this new study doesn’t mean that C-sections are necessarily responsible for hysterectomy complications or the second operations in the Danish women. But Shah thinks that we may be seeing this link because a C-section leaves scar tissue that can make any future operation in the same area of the body (such as a hysterectomy) more difficult.

That hypothesis is reasonable, says Elliot Main, M.D., the medical director of the California Maternal Quality Care Collaborative, a nonprofit organization that works to improve outcomes for mothers and babies. Scar tissue “distorts the normal anatomy and makes it hard to do the surgery,” he says, which could contribute to hysterectomy complications.

Main points out, however, that the most significant long-term risks of C-sections arise when women decide to have additional children. When women who have previously had C-sections give birth again, they are at far greater risk for delivery complications such as a ruptured uterus, hemorrhage (uncontrolled bleeding), and an unplanned hysterectomy—and those risks are even bigger when they’ve had a second C-section.

According to data collected in 2013 from the Centers for Disease Control and Prevention, women who had a previous C-section and gave birth vaginally during their next birth were about four times more likely to need an unplanned hysterectomy than those who’d never had a C-section.

And women who had a previous C-section and then another C-section with a subsequent birth were almost 12 times more likely to need an unplanned hysterectomy.

Overall, Main says, “It’s clear that having a C-section puts you at risk for operative complications and subsequent surgeries.”

How to Reduce Your Risk of C-Section

This new study evaluated C-section and hysterectomy rates in Denmark because data is available there for the entire country’s population. Denmark’s overall C-section rate is 21 percent, whereas the U.S. rate is almost 32 percent.

“The harm that we measured in Denmark is likely to be much smaller than the harm in the U.S.,” Shah says.

Though some women need to give birth by C-section for medical reasons, survey evidence suggests that most would prefer to give birth vaginally, according Doris Peter, Ph.D., director of the Consumer Reports Health Ratings Center. She says that although it’s up to hospitals to implement the procedural changes that will lower their C-section rates, women aren’t powerless when it comes to decisions about how they give birth.

“This study underscores how important it is for women to avoid a medically unnecessary C-section,” Peter says. “Women can use data on C-section rates in hospitals and talk with their doctor or nurse midwife to make sure they are choosing the right hospital for them.”

Here are strategies to try:

Pick your hospital carefully. A recent Consumer Reports analysis showed that a woman’s biggest C-section risk may be the hospital where she gives birth. If possible, find out your hospital’s C-section rate ahead of time. (Our tool to look up hospital C-section rates is currently being updated with new data; you will be able to look up your hospital again in September. Until then, ask your provider about the hospital’s C-section rates.)

Have a conversation with your doctor. Let him or her know you prefer a vaginal delivery, and would like to avoid a C-section unless absolutely necessary. If the doctor seems unreceptive, consider switching. (But remember that because of hospital scheduling, the doctor you see for prenatal care isn’t always the doctor who ends up delivering your baby—that’s why the hospital’s overall rate is so important.)

Slow down any rush to the hospital, or to delivery. Unless you live hours from where you plan to give birth, you may not need to hurry in as soon as you begin labor. Talk with your doctor about how long it’s safe to wait. And according to the American College of Obstetricians and Gynecologists, a long labor alone isn’t sufficient cause for a C-section.

For more information on how to reduce your C-section risk, you can find our report here.