Gynecology >> Intrauterine Systems: Mirena


What Is Mirena?

Mirena is an intrauterine contraceptive that continuously delivers a small amount of hormone called progestin directly to the uterus. Made of soft, flexible plastic, it is put in place by your healthcare provider during an office visit.

What Mirena does:

  • Offers birth control that is 99.7% effective.
  • Prevents pregnancy for up to 5 years
  • Reduces menstrual flow Returns you to fertility within one month of removal
  • Keeps hormone levels steadier and lower than the pill

What Mirena does not do:

  • Make your cycles regular
  • Cause weight gain Improve acne conditions
  • Keep you from ovulating or prevent ovarian cysts
  • Treat endometriosis

How Mirena Works:

There is no single explanation for how Mirena works. Mirena may:

  • Thicken cervical mucus to prevent sperm from entering your uterus
  • Inhibit sperm from reaching or fertilizing your egg
  • Make the lining of your uterus thin

Mirena may stop the release of your egg from your ovary, but this is not the way it works in most cases. Most likely the above actions work together to prevent pregnancy. Like other forms of birth control, Mirena is not 100% effective.

What Mirena looks like:

Mirena is a tiny T-shaped piece of soft, flexible plastic that is placed in the uterus by your healthcare provider during an office visit. It's designed to be small and comfortable, so that you and your partner most likely won't even feel like it's there. 

Is Mirena Right for Me?

You are a good candidate for this IUD if:

  • You have had a baby
  • You don’t want to have another baby for one or more years
  • You don’t want to get pregnant again
  • You are breastfeeding your baby
  • You need emergency birth control
  • You want to avoid surgical sterilization (getting your tubes tied)
  • You have one safe partner for sex and are not high risk for sexually transmitted infections. 

Mirena is not appropriate for women who:

  • Who are pregnant or might be pregnant
  • Have had a serious pelvic infection 
  • May currently have an infection
  • Have unprotected sex with more than one partner
  • Problems with your immune system
  • Are HIV positive or have AIDS
  • Unexplained uterine or vaginal bleeding
  • Cervical cancer
  • Breast cancer that is hormone sensitive
  • Uterine malformations or tumors (called fibroids)
  • Are allergic to levonorgestrel, silicone or polyethylene 

Birth Control After Your Baby:

Although breastfeeding full time will delay ovulation and menstruation for a number of months, the effectiveness of breastfeeding is quite variable and not reliable 2-3 months after delivery. The IUD is ideal for new mothers who may find daily pill taking or condom use difficult.

The IUD is safe while breastfeeding. Small amounts of the hormone in Mirena can be found in the breast milk of nursing mothers. This is not likely to affect the quality or amount of your breast milk or the health of your nursing baby. 

An IUD is generally placed 6-12 weeks after your delivery during a simple office procedure. When you may have an IUD placed will depend upon your delivery (vaginal or cesarean) and recovery.

When Mirena should be placed: Mirena should be placed within 7 days of your period. Or 6-12 weeks after delivery of your baby.

What Mirena Users May Expect:

Your provider will ask you to eat and take 600mg. of ibuprofen and hour prior to your appointment to have your IUD placed. Pre-treating with ibuprofen will minimize the mild cramping that often occurs during after placement.

This cramping may persist for 1-5 days after placement. The cramping should be mild and respond well to ibuprofen.

Often, the provider who placed your IUD will advise you to have it checked in 4-6 weeks in the office to assure you that the IUD is still in the uterus and providing the promised level of birth control. If the IUD will be expelled, it usually occurs during this time frame.

IUD’s can be expelled in the future also. Checking the strings of your IUD and monitoring and calendaring your menstrual cycles can help assure you that your IUD remains in the proper location.

Your Periods Will Change:

During the first three to four months of use most women experience bleeding between their menstrual cycles. Although you cannot expect the IUD to make your cycles regular (like a birth control pill), you can expect your cycles to become lighter over the next year.

After your body adjusts, the number of bleeding days will decrease (but may remain irregular), and you may even find that your periods stop altogether. Your periods will become lighter and lighter. By one year, about 1 out of 5 users may hay have no period at all.

Your periods will return once Mirena is removed. Fertility is restored within one month of removal.

Nearly Perfect Birth Control:

No birth control method is 100% effective. If you do get pregnant while using a birth control method, there can be risks to you and your baby.

About 2 in 1000 women using Mirena for one year may become pregnant. Sometimes when a woman gets pregnant with the IUD in her uterus the pregnancy will be in the fallopian tube. This is called an ectopic pregnancy. If your pregnancy test is positive while you are using the Mirena you should call the office immediately.

Usually when women become pregnant while using the IUD, it occurs because the IUD has been displaced (usually pushed down into the cervix) and is not providing pregnancy prevention. An ultrasound will allow your health care provider to locate the IUD and give you advice.

If your pregnancy is in the uterus, your health care provider will recommend removal of the IUD even if removal may cause a miscarriage. Severe infection, miscarriage, premature delivery and even death can occur with pregnancies that continue with an intrauterine device (IUD).

How Will I Know if My IUD has come out of the Uterus?

  • Abnormal Bleeding: Most women have a predictable bleeding pattern. Although your periods may not be regular, they will be light. So if you have a sudden increase in the amount of menstrual flow after many months of panty liner periods, you should see your provider to check your IUD.
  • Abnormal Pain: When your menstrual flow becomes this light you should not have any significant pain. If you have a significant increase in menstrual pain, you should see your provider to check your IUD 
  • Partner Complaints: Your sexual partner will likely be aware of, or even bothered by your IUD string. Over two to three months the string will wrap around your cervix and no longer bother your partner. So if, after many months of not noticing the IUD string, your partner complains of pain from the IUD string, you should see your provider to check your IUD. 
  • String Check: Your IUD string, which feels like fishing line, will protrude from your cervix about 2 inches. The string is not long enough to protrude from you vagina like a tampon. If you check your string and are unable to locate it or it is at the vaginal opening, then see your provider to check your IUD. 

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