A study in Spain has shown that a cervical pessary, a small ring-shaped device which is inserted around the cervix of women with a short cervix, may reduce the risk of premature labour.
In current medical practice, options for preventing preterm labour and birth tend to focus on identifying women at risk of having a preterm birth and managing their risk factors. Medical interventions to try to prevent birth and delivery are, however, limited.
This new research has focused on treatments for women found to have a short cervix (the opening to the womb), who have an increased risk of early delivery. It tested whether a simple silicone ring (pessary) placed in the vagina and over the cervix can help prevent preterm births, and found positive results for the ring.
The researchers found that pessaries in women with a short cervix (25mm or shorter) reduced the proportion of deliveries before 34 weeks of pregnancy, from 27% in women receiving standard treatment to just 6% in women given the pessary.
Pessaries of this kind have been used in medical practice for many years, but the evidence supporting their use has come from non-randomised trials. These can be influenced by bias as participants have their treatment chosen according to their circumstances. This latest trial has the benefit that patients were randomly allocated their treatment method, providing better evidence than non-randomised trials.
However, this exciting research needs to be confirmed in further larger studies of routine care in several other countries. It should also be noted that it is difficult to predict which women are likely to have a preterm birth. Only 6% of women initially screened in this study fulfilled this criteria, so we cannot tell if most pregnant women would derive any benefit from such a pessary.
Also, although gestational age at birth was increased with the pessary, the study was not large enough to assess some other important outcomes for babies. For example, the number of participants involved and the length of follow-up meant it cannot tell us about rates of rare but serious problems such as long-term illness or death, which have been linked to spontaneous preterm birth. The researchers stated that they have “planned a long-term follow-up of the infants until the age of two years to detect and compare developmental impairments in the two groups”.
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