Procedure to stop premature birth could affect babies – study

A routinely used procedure to prevent premature births could affect unborn babies, a new study shows.

The problem is the type of material used may promote the growth of dangerous bacteria.

A premature baby is born in Ireland every 116 minutes, according to the Irish Neonatal Health Alliance. The causes are not fully understood, but it is thought that vaginal infection in pregnant women can ascend through the womb and affect the developing baby.

To prevent this, a procedure called cervical cerclage is performed, where the cervix – a narrow channel at the base of the womb – is stitched. This procedure is believed to provide structural support and also act as a barrier to infection coming from the pregnant woman's vagina.

Two different types of thread are used for stitching in cervical cerclage: one is a single, thin filament and the other a braided, thicker, multifilament thread. The latter is used more frequently as it is stronger and is less likely to slip.

"Although the cervical stitch procedure still holds benefits for women overall, our results suggest the thicker thread may encourage the growth of potentially dangerous bacteria in the cervix. This may lead to premature birth or even loss of the baby," said Prof Phillip Bennett, lead author of the study from the Department of Surgery and Cancer at Imperial College London. The work was published in the journal Science Translational Medicine.

Researchers analysed recorded data from 671 women who had undergone the procedure with the different threads and found that using the thicker thread was associated with higher rates of preterm birth compared with using the single filament thread (28 per cent compared with 17 per cent).

Furthermore, there were also differences in the proportion of stillbirths, with the thicker thread associated with a 15 per cent rate of foetal death, compared with only 5 per cent with the thinner thread.

An experiment in the lab showed that dangerous bacteria were more likely to attach to the thicker, braided thread than to the thin one.

The researchers then carried out a clinical study in 50 women at risk of premature birth who had undergone the procedure using both thread types. Analysing the pregnant women’s birth canal, they found that use of the thicker thread caused alterations in the bacterial content, decreasing the proportion of harmless bacteria that keep dangerous bacteria at bay.

Switching to the thinner thread could prevent 170,000 premature births globally every year, and 172,000 foetal deaths every year across the world, the authors say.

Vanesa Martinez is on placement at The Irish Times under the BSA/SFI media fellowship programme