Questions have been raised in the U.S. over the safety and effectiveness of a hormone based drug which is used in women who have a history of pre-term births.
The U.S. Food and Drug Administration (FDA) will question whether the drug Gestiva, which is produced by the Adeza Biomedical company, is in fact safe and effective in preventing early births.
The FDA will ask a panel of outside experts whether more studies are needed before it can be recommended for women who have a history of giving birth too early.
According to the FDA data submitted by Adeza on the drug's effectiveness, it differs from the results of an earlier study, which also shows a possible increased risk of miscarriages and stillbirths in women who used it.
The FDA advisory panel will review the data and decide whether to recommend Gestiva now or advise further trials of the drug.
As a rule the FDA follows the advice of these panels.
Gestiva is a long-lasting, injectable form of the hormone progesterone which according to the manufacturer produces "a statistically significant reduction" in preventing pre-term births.
It is meant to be injected weekly between the 16th and 20th weeks of pregnancy through to the 36th week, or birth.
The company's trial found that 36 percent of women taking Gestiva gave birth too early, compared with 55 percent of women who did not take it, whereas previous data suggested the figures were the other way round.
The FDA does say that no maternal deaths were reported.
According to the March of Dimes, a baby health advocacy group, as many as 12 percent of all babies are now born prematurely (at less than 37 weeks of pregnancy), and the trend appears to be growing.
The risks of a premature delivery are greater for women who have had a premature baby before, are carrying two or more babies, or have certain reproductive abnormalities.