A new discovery might offer women an alternative to these hormonal contraceptives. Scientists have discovered a molecule called STAT3 that helps embryos implant. Apparently the molecule signals the cells of the uterus that they should allow an embryo to attach. If this signal is interrupted, a fertilized egg would be expelled from the body, rather than snuggly fed and cared for, thereby preventing pregnancy.
Lest we be misled into believing that women's health has somehow received extra reserach funding, I'd like to point out that the relevance of this molecule to pregnancy was discovered quite by accident. The researchers have been investigating STAT3 because of it's implication in the formation of tumours and diabetes. It just so happens that they discovered it is also partially responsible for initiating pregnancy. They suggest that compounds already under development for the treatment of the other conditions might provide contraceptive benefits.
It's still a few years off at best, but we may see a non-invasive, non-hormonal form of contraception. This would reduce some of the risks associated with hormonal forms, such as blood clots, and would do away with the androgenic side effects, such as weight gain, vaginal dryness, and mood swings, that some women experience with hormonal contraceptives. it would also, however, result in the loss of the many benefits related to the use of hormonal contraceptives, such as decreased risk of ovarian cancer and improvement of acne.