Pooled data indicate that progestogens may help prevent preterm birth among women who’ve delivered early in the past, according to researchers based in Tennessee.
But the evidence wasn’t very strong, and any benefit appears limited to singleton pregnancies.
As Dr. Frances E. Likis told Reuters Health by email, “Progestogens prevent preterm birth in women who have had a previous preterm birth but not in women who are pregnant with twins or triplets.”
In a September 5th online paper in Obstetrics and Gynecology, Dr. Likis of Vanderbilt University, Nashville and colleagues note that progestogen use “has become common practice over the past decade, although the mechanism for pharmaceutical effects is not well understood.”
To gain more information on immediate outcome, the team identified 34 randomized controlled trials involving 20 or more women. Included were all indications, formulations, and drug delivery routes. Bayesian meta-analysis was conducted in the 18 studies with appropriate data.
Among women with prior preterm birth and a singleton pregnancy documented in five trials covering preterm birth at less than 37 weeks of gestation, progestogen treatment decreased the median relative risk of preterm birth to 0.78 and of neonatal death to 0.58.
Together, three studies covering 707 women demonstrated benefit and the other two involving 644 women did not.
In multiple gestations, further analyses suggested that progestogen treatment does not prevent prematurity (relative risk, 1.02) or neonatal death (relative risk, 1.44).
In two studies of women with a short cervix there was an indication of prevention of pre-term labor (relative risk 0.52).
Overall, say the investigators, “Limited evidence suggests progestogen treatment may prevent prematurity in women with preterm labor (relative risk, 0.62).”
All other maternal, fetal, or neonatal outcomes, they write, “were reported by fewer studies or had incompatible definitions not appropriate for aggregate estimates.”
And, they add, “Evidence is insufficient for use of progestogens in groups broadly defined to be at high risk of preterm birth.”
They go on to say: “clinicians must be aware that current studies do not support progestogen treatment for all women with any risk factors for preterm birth.”
In addition, Dr. Likis concluded that “We have very little information about whether progestogens improve newborns’ health as well as the long-term health effects of these medications.”
– David Douglas
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