Pregnancy With Mirena: Is This Normal?

Mirena, known by its generic name levonorgestrel, is an IUD with progesterone contraception currently marketed by Bayer. It is a hormonal, long-acting, and reversible birth control device that is also used for managing menorrhagia (intense periods), anemia, dysmenorrheal, and preventing certain diseases like uterine fibroids and adenomyosis. After IUD placement, an initial 20 micrograms of levonorgestrel is released directly into the uterine lining, which decreases ovulation frequency, thickens cervical mucus to serve as natural barrier, and triggers the uterus to unleash a stream of prostaglandins and leukocytes that can kill sperm and egg cells.


In several comparative and non-comparative studies, the cumulative probability of pregnancy with Mirena is as little as one pregnancy in every 100 women for the use of Mirena IUD as compared to other non-hormonal IUD products. One trial has established 0-0.2% pregnancy rate for a one year study and 0.5-1.1% for studies that lasted for at least five years. This does not mean, however, that it is 100% effective compared to other competing birth control products as comparative studies show otherwise.

Side Effects

It has been reported that some Mirena users are experiencing symptoms of pregnancy with Mirena. Some claim that their breasts became tender, and they felt as if they were lactating. Other users verbalized that they have experienced increased urinary frequency, morning sickness, and developed cravings for certain food types. Other accompanying symptoms were the feeling of a bloated abdomen or stomach, frequent low back pain, dizziness, and even vomiting on some occasions.

Clinical tests show that for the initial 3-6 months, monthly periods may be irregular and the incidence of periods may seem to increase. Spotting and slight vaginal bleeding may be evident in the first months as well. But later on, the periods may eventually stop for the duration that the IUD is in place (temporary amenorrhea). This is probably one of the reasons why Mirena users sometimes think they have become pregnant because missing menstrual periods will become a normal occurrence. Other symptoms that are listed as probable side effects of Mirena use include:

  • Dizziness, headache, and migraine
  • Nausea
  • Abdominal pain
  • Acne development
  • Mood swings or mood alterations (i.e., frequently depressed)
  • Back pain
  • Breast tenderness

As you can see, these symptoms are usually present during pregnancy. But these symptoms of pregnancy with Mirena normally occur during the first months of IUD use.


There are already a lot of studies conducted to test the safety of Mirena as compared to other methods of contraception like Cu-IUDs. The majority established that:

  • Mirena use does not lead to weight gain.
  • There is low risk of pelvic inflammatory disease and breast cancer development.
  • There is low Mirena pregnancy incidence, specifically ectopic pregnancy.
  • Mirena use has been observed to improve hemoglobin, serum protein, and serum ferritin levels.

Although Mirena has been noted to be safe and very effective for use, it must be replaced with a new set every five years. You can still use tampons if you're using this device.