Weight gain can be an issue for women of all ages. The last thing you want to worry about when choosing birth control is gaining weight. Yet weight gain is a reported side effect of many birth control methods. Is the copper intrauterine device (IUD) one of them?

An IUD is a T-shaped, plastic device implanted into the uterus to prevent pregnancy. There’s only one type of copper IUD, and it’s called ParaGard. A copper wire is coiled around the stem of the device and copper sleeves cover each arm. ParaGard continually releases copper into the uterine lining. The copper is lethal to sperm and helps prevent fertilization.

Other types of IUDs release hormones into the body. These hormones thicken cervical mucus to help prevent sperm from moving towards an egg. All IUDs have a string attached so you can make sure it’s in place. This string also helps your doctor remove the device. If you want to become pregnant, an IUD can be removed any time.

IUDs don’t prevent sexually transmitted diseases (STDs). If you’re at high risk of contracting one, you’ll need to use condoms as well.

IUDs top the list of effective birth control methods with less than one pregnancy per 100 women each year. Once it’s inserted, the ParaGard copper IUD helps prevent pregnancy for up to 10 years. Hormonal IUDs help prevent pregnancy for three to five years.

Since a copper IUD has no hormones, the side effects are less severe than those of hormonal IUDs or other forms of hormonal birth control. The side effects can include:

  • anemia
  • a backache
  • breakthrough bleeding, or bleeding between periods
  • cramping
  • vaginal inflammation
  • pain during sex
  • severe menstrual pain
  • heavy periods
  • vaginal discharge

In rare cases, an IUD is expelled from the body. This is more likely to happen if any of these apply:

  • you’ve never been pregnant
  • you have heavy periods and severe menstrual pain
  • you’ve expelled an IUD before
  • you’re under age 20
  • you had the IUD inserted immediately after childbirth or after an abortion in the second trimester

There’s a slight possibility of perforating the wall of the uterus, particularly during placement. If perforation occurs, the IUD should be removed and surgery may be needed. Perforation may cause infection, scarring, or damage to other organs.

Weight gain isn’t listed as a side effect of ParaGard. Anecdotal evidence from women using the device indicates IUDs cause weight gain, but scientific evidence is inconclusive.

A study published in Contraception assessing weight changes in Brazilian women using copper IUDs found that weight increased, especially in older women. It was also determined that the women tended to gain weight during their reproductive years independent of IUD insertion. Because of this, weight gain may have been related to age.

A more recent study published in the European Journal of Contraception & Reproductive Health Care compared weight gain in women who used hormonal contraception or IUDs. The study found users of both types of birth control gained significant weight over a 10-year period.

Although these studies indicate IUD users experienced weight gain, it’s unclear if the gain was due to the IUD or normal aging and lifestyle factors such as diet and exercise. Removing the IUD didn’t necessarily result in weight loss. More research is needed to put an end to the debate about weight gain and IUDs.

Birth control is a personal choice that should be weighed carefully. Most women can safely use a copper IUD, but you should consider other options if you have any of these risk factors:

  • uterine abnormalities that interfere with placement
  • a pelvic infection
  • uterine or cervical cancer
  • unexplained vaginal bleeding
  • allergies to any components of the IUD
  • Wilson’s disease, which causes the accumulation of copper in the brain and other organs
  • a high risk of having an STD
  • a history of problems with an IUD

Which Birth Control Is Right for You?

A copper IUD is a great option for women who want to avoid hormonal birth control or want the convenience of not having to think about birth control in the long term. When it comes to weight gain, the definitive verdict is still out. Eating a healthy diet and staying active may help reduce your risk of packing on extra pounds. Talk to your doctor if you’re interested in using a copper IUD but are concerned about weight gain.