Stem pesaries are intra-uterine devices (IUDs) consisting of a rubber, metal, or glas stem attached to a cup or button to hold the stem upright and prevent it from becoming lost in the uterus. An IUD works after conception by denying a newly fertilized embryo the ability to implant and grow in the lining of the uterus. The IUD is the most inexpensive long-term reversible method of contraception available. Smaller, plastic IUDs are still used today.
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