| Excerpt from The WHO Reproductive Health Library | Published by Update Software Ltd. |
The review analysed data from 14 randomized controlled trials involving 1988 women. Most rials included women at some level of perceived increased risk of miscarriage (previous miscarriage, threatened abortion, uterine procedure such as amniocentesis).
There was no statistically significant difference in the risk of miscarriage between groups receiving progestogen or a placebo. Also, the route of administration of progestogen (oral, intramuscular, or vaginal) appeared not to be associated with a statistically significant difference in miscarriage rates. Interestingly, progestogen administration showed a small but statistically significant decrease in the miscarriage rate compared with placebo (OR 0.37; 95%CI 0.17–0.91) in a sub-group of women who had experienced recurrent miscarriages, defined as patients who had suffered three or more consecutive miscarriages. These result should be interpreted with caution because the number of subjects was small and the confidence interval wide.
The findings of the review remain unchanged when the data from a recent trial (1) are also taken into account.
No maternal adverse effect was identified. While slightly more fetal/neonatal adverse events, namely fetal abnormalities and neonatal deaths were identified among women receiving progestogen, the number was far too small—partly because of the rarity of such events—to qualify as a potential risk.
Threatened miscarriage—the most common clinical situation necessitating progestogen treatment—was not separately analysed in the review. In a recent meta-analysis, Sotiriadis and colleagues (2) did not find statistically significant reduction in miscarriage rate among threatened miscarriages who received progestogen treatment (OR 1.1; 95%CI 0.92–1.31). A sub-group analysis for those having sonographic evidence of fetal heart activity at presentation yielded a similar result (2).
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