In 2003, an old medication that was used in the 1960’s to try and prevent preterm birth, was re-introduced to the obstetrical world. Delalutin or 17-alpha hydroxyprogesterone acetate was used in a multi-center study on patients with one previous preterm birth. The experimental group had weekly shots of 250 mg from 16 – 36 weeks of pregnancy. The study showed that the placebo group delivered prematurely 56% of the time and the progesterone group delivered 36% of their babies prematurely.
While these statistics seem promising, the study was criticized for having a very high preterm delivery rate of the “control” group, higher than historically expected. Additionally, a one out of three preterm delivery rate while using weekly injected progesterone shots, compared to a one out of two risk with no shots, is not very impressive.
As an important note, injectable progesterone has proven ineffective in multiples, in patients with a cervix that is > 20 mm in length, and once preterm labor has already begun.
Since there is only a 20% historical risk for preterm delivery with one previous delivery, Dr. Berry and Austin Perinatal Associates offer progesterone injections to patients with one previous preterm delivery, but with considerable caution that it may be of no benefit 80% of the time.
For patients at higher risk for preterm birth, for instance those with multiple previous preterm deliveries after 24 weeks, in the absence of other potentially effective therapies, Dr. Berry encourages progesterone injections.