List of products in the National Drug Code with proprietary name . This medication is used in women who are pregnant with a single baby, and who have delivered a baby too early (preterm) in the past. It is used to help lower the risk of having a preterm baby again. Hydroxyprogesterone is a man-made form of a female hormone (progestin). It is not known how it works to prevent preterm births. This medication is not intended to prevent preterm birth in women pregnant with more than one baby (such as twins, triplets). It is also not intended to stop active preterm labor.