If your method of birth control is the Depo-Provera shot (depot medroxyprogesterone acetate; DMPA), or if you're considering using this method, make sure your physician is aware of the latest ACOG Committee Opinion, in particular:
1. Most of the DMPA bone loss is temporary and is similar to the BMD loss caused by pregnancy and breastfeeding [~3%-5% vs. 2%-8% and 3%-5%].
2. Its use should not be limited to 2 years.
3. Concurrent low-dose estrogen supplementation to slow DMPA bone loss is not recommended.
4. Implants and IUDs--effective, long-term methods of contraception that have no effect on bone density--should also be considered as first-line methods for adolescents.
5. The scientific basis for the 2004 Food and Drug Administration black box warning discouraging the use of DMPA for more than two consecutive years is caca*.
*Okay, that characterization is entirely mine. According to ACOG, the FDA's warning is based on intermediate effects on BMD which may or may not be relevant to increased risk of fracture (former adult DMPA users have BMD rates similar to nonusers) and, while low BMD is linked to an increased risk of fracture in older women, no studies have linked DMPA bone loss with increased rates of fracture in younger women with a low-fracture risk.
N.B. Speaking of Depo-Provera, don't forget you also have a lower-dose version, Depo-subQ, available.