Background:

Hydroxyprogesterone caproate is a synthetic, steroidal progestin; an ester derivative of 17α-hydroxyprogesterone formed from caproic acid.

参考文献:
[1]. Armstrong J. Unintended consequences--the cost of preventing preterm births after FDA approval of a branded version of 17OHP. N Engl J Med. 2011 May 5;364(18):1689-91.
[2]. Hauth JC, et al. The effect of 17 alpha-hydroxyprogesterone caproate on pregnancy outcome in an active-duty military population. Am J Obstet Gynecol. 1983 May 15;146(2):187-90.