Treatment for cervical disease is not linked to increased risk of preterm births

by Bruce Sylvester – taken from The British Medical Journal (BMJ) –

Contradicting previous research, researchers from a study of over 44,000 women in England report that treatment for cervical disease does not appear to increase the risk of subsequent premature births. The study was published online Aug. 16, 2012 in the British Medical Journal. It is the largest study to date of the issue.

Lead investigatior, Professor Peter Sasieni, professor of cancer epidemiology and biostatistics at the Wolfson Institute of Preventive Medicine, part of Queen Mary, University of London, UK, said. “This finding is significant because approximately 40,000 women (most of whom are of child-bearing age) receive such treatment each year, and scientific literature had previously suggested that if any of these women became pregnant they would have an extra risk of about one in 18 (5.6%) of having a preterm birth. Considering all those treated previously who may be planning to have children, there may be half a million women in the UK who can relax now and not worry that they are at increased risk of a preterm birth.”

As background the investigators noted that women between the ages of 25 and 64 in England are encouraged to have cervical screening every three to five years. Treatment for moderate or severe changes (cervical intraepithelial neoplasia (CIN) 2, or 3) involves removal of abnormal  tissue.  The most widely used technique in England is large loop excision of the transformation zone (LLETZ). Previous studies have suggested that treatment, including LLETZ, might  increase the risk of subsequent preterm birth (before 37 weeks).

Professor Sasieni and his colleagues from the Pre-term delivery after Cervical Treatment (PaCT) study group correlated data for 44,210 women in England who had had cervical tissue samples taken, with hospital obstetric records,  to 18,441 subsequent births (excluding twins and triplets). They evaluated for the proportion of preterm births, both before and after colposcopy, and compared women who had been treated by LLETZ with those who had only had a diagnostic biopsy. They also compared preterm delivery rates with rates for the whole of England.

They found that, compared to the general population of women in England (6.7% had preterm births), women in this study had just over two extra premature births per 100 births (8.8% preterm).

Adjusting for the type of treatment and whether it had occurred before or after the birth, the researchers concluded that there was no increased risk associated with treatment. The researchers also concluded that the increased risk of preterm birth in women who have been treated for cervical disease was due to common factors that increased the risk of both cervical disease and preterm delivery, and not to the treatment itself.

“Women should have more confidence in going for cervical screening and accepting the treatment offered to them,” said Sasieni. “Large loop excision of the transformation zone should still be seen as the treatment of choice. It would be premature to start using other treatments such as cryotherapy that may be less effective in treating cervical disease, in the hope that it would result in fewer preterm births.”

Professor Julietta Patnick CBE, Director of the NHS Cancer Screening Programmes, said: “We welcome these positive findings about the safety of treatment procedures for cervical disease in England. They are an encouraging reflection of the high standards of our NHS practitioners and our robust system of quality assurance. However, previous studies have shown that treatments, including colposcopy and LLETZ, are linked to an increased risk of pre-term deliveries, and it is important that we continue this project to provide firm evidence in this important area. Regular attendance at screening remains the top preventative measure against cervical cancer and we would encourage all women to make the decision to attend when invited.”