Intrauterine Device (IUD) Types and Evidence‑Based Clinical Guidance

IUD Categories

The two fundamental IUD categories are copper‑bearing devices and levonorgestrel‑releasing (hormonal) devices. 1

The only copper IUD marketed in the United States is the Copper T380A (ParaGard). 4

Approved for up to 10 years of continuous use with a typical‑use failure rate of < 1 % per year. 4
Can be inserted at any point in the menstrual cycle provided pregnancy has been reasonably excluded. 4

When placed within 5 days of unprotected intercourse, the copper IUD prevents > 95 % of unintended pregnancies, making it the most effective method of emergency contraception. 4

Contains no hormones; contraceptive effect is achieved primarily by copper’s toxic effect on sperm, preventing fertilization. 1
Does not provide protection against sexually transmitted infections (STIs) or HIV. 1

The principal side effect is increased menstrual bleeding and cramping, which may persist with long‑term use. 2

Device	Levonorgestrel Reservoir	Daily Release	Approved Duration	Notable Efficacy Data
Mirena	52 mg	20 µg	5 years (effective up to 7 years)	Cumulative failure rate 0.68 % during years 6‑8
Liletta	52 mg	20 µg	3 years (potential extension)	—
Skyla	13.5 mg	14 µg	3 years	Lower‑dose option introduced in 2013

All devices act by inhibiting sperm motility, thickening cervical mucus, and altering endometrial environment—mechanisms that occur before implantation. 2
Classified as progestin‑only contraceptives; they contain no estrogen. 2

The 20 µg/day devices (Mirena, Liletta) reduce menstrual blood loss by 71‑95 %. 2
Many users experience lighter periods or complete amenorrhea. 2
Only Mirena has been formally evaluated and shown to be effective for treating heavy menstrual bleeding; Skyla has not been studied for this indication. 2
Levonorgestrel IUDs are useful for adolescents requiring long‑term menstrual suppression when estrogen is contraindicated. 2
They also reduce dysmenorrhea and provide therapeutic benefit for endometriosis and adenomyosis. 3

Changes in bleeding patterns (including amenorrhea) do not correlate with contraceptive failure; efficacy is maintained regardless of bleeding profile. 2

Both copper and levonorgestrel IUDs have typical‑use failure rates of < 1 % per year, placing them among the most effective reversible contraceptives. 2
They are safe for nulliparous individuals and adolescents; nulliparity is not a contraindication. 2
Fertility returns rapidly after removal. 2
Insertion can be performed immediately postpartum or after an abortion. 3
The risk of pelvic infection is confined to the first 20‑21 days after insertion; beyond this period, IUDs do not increase rates of STIs or pelvic inflammatory disease. 2
Neither copper nor hormonal IUDs protect against STIs or HIV; consistent condom use is advised when STI/HIV risk exists. 1
Expulsion occurs in 5‑10 % of insertions within five years, with higher rates in younger nulliparous users. 4
Women with uterine fibroids have an approximate 11 % expulsion risk versus 0‑3 % in those without fibroids. 2

Contraception‑only indication: Either copper or levonorgestrel IUD may be chosen based on patient preference and any contraindications to hormones. 3
Heavy menstrual bleeding: Select Mirena or Liletta (20 µg/day devices) as they have established evidence for treating menorrhagia. Skyla has not been studied for this use. 2
Emergency contraception: The copper IUD is the sole IUD option and must be inserted within 5 days of unprotected intercourse. 4