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.
Smoking or drinking alcohol as well as some diseases such as diabetes can also increase the risk of premature birth.
Gestiva would be the only FDA-approved drug to prevent preterm birth, but the FDA says many pharmacists concoct the drug themselves and doctors also use other drugs that are known to stop contractions and to prevent early birth, but lack FDA approval.
Adeza says FDA approval is essential for consistent information on dosing to be provided and to ensure consistent drug quality.
Adeza also says that prolonging the time a baby is in the womb by as little as one week would improve a baby's health and increase its chance for survival, and is a consideration when the the high costs of caring for premature babies are taken into account.
Babies born anytime after 32 weeks generally survive without serious, long-term developmental problems, but babies born before 32 weeks which make up just 2 percent of births, account for most cases of death and problems among preemies.
A 2003 March of Dimes report estimated that U.S. hospitals spent $36.7 billion on infants and half of that, $18.1 billion, was spent on those born to soon or too small.