Women in the progesterone group receive weekly injections of the drug starting at 16 to 20 weeks of pregnancy and continuing up to 36 weeks of pregnancy. The study found that progesterone treatment significantly reduced the risk of preterm birth in less than 37 weeks.
"There was a 66% drop in the rate of recurrent preterm births among women taking progesterone," says Dr. Eva Pressman, Department of Obstetrics and Gynecology at the University of Rochester. "We believe that progesterone acts as a uterine muscle relaxant, which seems to reduce the ability of the uterus to contract," Presman explains.
With the extremely useful findings of this study, the drug was quickly followed by the FDA approval process, with one major caveat: the Makena manufacturer is required to do a larger follow-up study to confirm the benefit of the drug.
But the findings were not so. A subsequent study published in late October found that Makena "did not reduce recurrent preterm births"
The FDA Advisory Committee was tasked with reviewing all the evidence and determining whether the benefits of the drug outweighed the risks. The Agency should not follow the recommendations of an advisory committee, but it usually is.
Dr. Christopher Zan, vice president of practice at the American College of Obstetricians and Gynecologists, says he believes MacKen's withdrawal would be a mistake.
While the second study "is designed to be a confirmatory test, there are some factors that make it difficult to interpret," says Zan. Although much larger than the first study, the second includes a much higher percentage of women at low risk of preterm birth.
This makes direct comparisons of the conflicting findings of the two studies difficult, says Zan, and emphasizes the need for further confirmatory research.
Makena is the only drug currently available to prevent preterm birth, Zan notes, and is now the standard of care for high-risk women who have previous preterm birth.
"It is one thing to raise concerns about conflicting data," he says, "but if this particular drug is not available, it is no longer available." Zan worries that pulling the drug could lead to premature birth disease which creates many tragic problems for babies.
"It is well known that babies born prematurely are at increased risk of poor outcomes – including death – and that the risk decreases with increasing gestational age," says Zan. After birth, he adds, premature babies may have " breathing or breathing problems, impaired organ function, visual impairment and hearing and delayed nervous development. "
In response to the recommendation of the Advisory Committee, ACOG issued a statement stating that its current guidelines would remain in force for the time being. Part of the manual of ACOG states: "A woman with a single pregnancy and preterm spontaneous preterm birth should be offered a single progesterone supplement starting at 16-24 gestational weeks to reduce the risk of recurrent spontaneous preterm birth."
Obstetrician-obstetrician "The group also says that it will" follow up on this topic, evaluate the additional literature and any additional analyzes as published. "
Preschman said she agreed that more study was needed on the relative utility of the drug. And notes that the University of Rochester Medical Center, where he works, would not advise discontinuing medications for women who have already received weekly injections – "because there is some evidence that withdrawing progesterone and stopping treatment may increase the risk of preterm birth more than if they had not started in the first place. "
Lewis also calls for more research to better understand conflicting data. According to her, some patients need to be treated for this very serious condition and doctors and other providers want to do the best for these patients.
But at the moment she says, "It is very difficult to make a choice based on the evidence we have. "