[The new IUDs]

This brief review mentions 3-dimensional IUDs and large surface IUDs and discusses progesterone and copper-containing IUDs. The 3-dimensional IUDs (Corolle, Basquet, and Majzlin spring) were expelled easily and were poorly tolerated. The large area Dalkon shield was difficult to insert and remove but permitted few expulsions; the failure rate of less than 1% claimed by its inventors has not been confirmed in French and British studies. IUDs with progesterone capsules or with auxiliary daily pills are on trial. Copper T and 7 shaped IUDs have proved to be more effective, seldom expelled, and rarely responsible for severe bleeding. The IUDs with 300 sq. mm copper release about 50 mcg copper /day, not enough to affect blood levels. They seem to prevent implantation by attracting leukocytes and macrophages, by modifying mucosa enzymes such as acid phosphatase, and by preventing sperm from penetrating cervical mucus.