Reducing the Risk of Recurring Preterm Birth: 10 things you need to know about 17P

What is 17P?

17P is the name of the drug therapy used to help prevent repeat preterm birth. It stands for 17 alpha hydroxyprogesterone caproate (17-HPC).  It is a synthetic form of the female sex hormone progesterone.   According to a report released in 2003 by The National Institute of Child Health and Human Development, weekly injections of 17P reduced the chance of repeat preterm birth by one-third as well as decreased the rate of neonatal morbidity. It is one of the few clinically effective and cost effective strategies to combat recurrent preterm birth.

Do all women benefit from 17P?

17P has been found to be effective in women who have a history of a previous singleton spontaneous preterm birth who currently have a singleton pregnancy.   The studies conducted to date have shown that progesterone is not effective in preventing premature delivery in pregnancies at low risk for prematurity, multiple gestations, or in patients once preterm contractions have begun.

What is its relationship to the prevention of preterm birth?

The exact mechanism by which progesterone prevents preterm birth is unknown. However, it has been shown to decrease inflammation and blocks the effect of oxytocin on the myomentrium. In short it relaxes the uterus.
**Oxytocin is a hormone that is present in the later stages of pregnancy which aids in uterine contractions.
**Myometrium is the muscular outer layer of the uterus.

What is the common procedure followed for the distribution of 17P?

A preferred use of progesterone is a weekly intramuscular injection of 250mg of 17-hydroxyprogesterone ideally starting at 16 weeks gestation and continuing to 36 weeks and 6 days.

 How much more time are the weekly injections of 17P allowing women to carry out their pregnancy compared to their untreated counterparts?

Meis et al. reported that the weekly injections could result in a 33% reduction in the rate of preterm delivery prior to 35 weeks gestation and 42% reduction prior to 32 weeks gestation.  This same study found a decrease in morbidity in the NICU with significantly lower rates of necrotizing enterocolitis, intraventricular hemorrhage and the need for supplemental oxygen.  The lower rates are a result of the increase in gestational age.  It is important to note that 17P does not guarantee a full term birth however, each day provides valuable time in which the fetus can continue develop. 

How long has research on the relationship between 17P and the prevention of preterm birth been taking place?

17-HPC is not new, it has been around since the late 1950’s under the FDA approved name of Delautin.  Deluatin was used for the treatment of habitual and recurrent miscarriage, threatened miscarriage and postpartum after pains.  It was voluntarily taken of the market in 1999 for reasons not related to safety or effectiveness.  Studies specifically relating to 17P and the prevention of preterm birth have been taking place since the 90’s.

Does  17P pose any health or medical risks to the fetus?

In the studies conducted on 17P, mothers who took 17P did not have an increased risk for birth defects nor were there findings to suggest a difference in the development of health problems. 

Is 17P safe for mothers?

In women who take 17P to reduce their risk for recurring preterm birth, there are minimal risks.  The most common problems are soreness, irritation, itching, bruising, swelling and pain that can occur at the injections site.

The Food and Drug Administration (FDA) has not approved 17P for the specific purpose of preventing preterm birth.  What does this mean?

Currently, 17P is available through compounding pharmacies and is not marketed under a specific drug name.  However, in the fall of 2006, the FDA advisory committee recommended 17P for full FDA approval for the specific purpose of preventing preterm birth.  This would allow17P to be manufactured as the drug Gestiva and make it available through all pharmacies.  Final approval is pending.

Is 17P safe for mothers more severe side effects may occur in rare circumstances. 

  How do I learn more about 17P?

To learn more about 17P please speak with your doctor.  The information provided in this section is for informational purposes only.  

Meis PJ, Klebanoff M, Thom E, Dombrowski MP, Sibai B, Moawad Ah, et al. Prevention of recurrent preterm delivery by 17 alpha-hydroxyprogesterone caproate. N Eng J Med 2003;348:2379-85.

http://mombaby.org/index.php?c=2&s=58&p=340

http://www.marchofdimes.com/prematurity/21236_19093.asp