Minor operation greatly boosts risks of very premature births

Dilation and curettage -- D&C -- is routinely used by doctors after miscarriage or pregnancy termination, but researchers found it upped the risk of very premature births by nearly 70 percent.

The procedure entails dilating the cervix and removing any tissue remaining in the womb to prevent infection.

Generally considered safe and easy to preform, the 15-minute operation is being rivalled by less invasive methods but remains common.

In a review of 21 studies covering two million women, Dutch researchers found that D&C increased the risk of premature birth -- when a baby is born before 37 weeks -- in a subsequent pregnancy by 29 percent.

The risk of very premature birth -- before 32 weeks -- rose by 69 percent however. At this young age, a baby is at risk of medical complications, most require oxygen to help them breathe, and many need to be fed intravenously.

In the general population, the risk of pre-term delivery without a D&C is about six percent, the research found. The additional risk from the operation brings the figure to 7.6 percent.

The results "warrant caution in the use of D&C after miscarriage and induced abortion," said Pim Ankum of the Academic Medical Centre at the University of Amsterdam.

Dilation may impair anti-microbial defences, causing genital tract infection, or weaken cervical tightening, both known factors for premature birth, suggested Ankum.