The chances of developing osteoporosis and cardiovascular problems increase with feminizing hormones.
A 2012 paper  found that a quarter of the male-to-female transsexuals it studied had osteoporosis at the lumbar spine and radius.
In the same study, 6% of male-to-female transsexuals experienced a thromboembolic event (a blood clot causing obstruction), and another 6% experienced other cardiovascular problems. These effects were observed after only 11.3 years of hormone treatment on average.
A further study  found that long-term bone mineral density decreases in transwomen who take cross-sex hormones in the long term.
 Wierckx, K., Mueller, S., Weyers, S., Van Caenegem, E., Roef, G., Heylens, G. & T’Sjoen, G. (2012). Long-Term Evaluation of Cross-Sex Hormone Treatment in Transsexual Persons. The Journal of Sexual Medicine 9 (10): 2641-2651. [Link]
 Delgado-Ruiz, R., Swanson, P., & Romanos, G. (2019). Systematic Review of the Long-Term Effects of Transgender Hormone Therapy on Bone Markers and Bone Mineral Density and Their Potential Effects in Implant Therapy. Journal of clinical medicine 8 (6): 784. [Link]