Discovered in 1953, Hydroxyprogesterone-caproate is a medication used to prevent preterm birth in pregnant women with a history of the condition and to treat gynecological disorders. It is still not known how this medication works to prevent preterm births, though. Also known as Makena, this medication is typically given to women who are currently pregnant but have delivered at least one other baby before week 37 of pregnancy. It is worth noting that the biggest risk of getting a progesterone injection, such as Hydroxyprogesterone-caproate, during pregnancy is a blood clot. So, you should call your doctor right away if you experience a sudden pain or swelling in one of your legs, a reddened area on your leg, or shortness of breath or trouble breathing. And even though there is no evidence of fetal risk with use of this medication during pregnancy, Hydroxyprogesterone-caproate may still increase the risk of gestational diabetes when used in pregnant women.