Intrauterine Device (IUD)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 14, 2026

An intrauterine device (IUD) is a small, T-shaped contraceptive device placed inside the uterine cavity. Two primary types exist: copper and hormonal. The copper IUD works without hormones. Copper ions impair sperm motility and inhibit fertilization. At higher concentrations, copper may also alter the endometrial environment in ways that affect implantation, though the primary mechanism operates before fertilization.

The hormonal IUD releases levonorgestrel, a synthetic progestin, locally into the uterine cavity. It thickens cervical mucus, thins the endometrial lining, and may suppress ovulation in some users, particularly in the first year of use. Whether post-fertilization effects occur is scientifically contested and directly relevant to informed consent for couples who consider fertilization the beginning of a new life.¹

Both types carry known side effects. The copper IUD frequently causes heavier menstrual bleeding and increased cramping. The hormonal IUD frequently causes irregular bleeding or amenorrhea. Amenorrhea eliminates menstrual cycle data as a diagnostic source, removing information that restorative clinicians rely on to identify hormonal patterns and underlying conditions. Both types carry a small risk of expulsion, uterine perforation at insertion, and pelvic infection.

Fertility Awareness-Based Methods provide an alternative to intrauterine contraception with equivalent effectiveness when used correctly, without a device, systemic or local hormonal exposure, or the post-fertilization mechanisms that have prompted ongoing scientific and ethical discussion. For couples who want to understand their cycle rather than suppress or override it, FABMs support that goal directly, alongside body literacy and restorative care.

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.