PORTLAND – A study of more than 9,000 women in Maine suggests a link between a thyroid condition and miscarriage late in pregnancy.

The study, published last week in a European medical journal, found that women who have an underactive thyroid are four times more likely to miscarry in the second trimester than other women.

Researchers who conducted the study say that an underactive thyroid, a condition known as hypothyroidism, may be connected to as many as six of 100 late-term miscarriages.

“That’s, of course, quite a tragedy when you have a second-trimester pregnancy loss because your pregnancy’s well along and you’re pretty confident that everything’s OK at that point,” said Dr. Walter Allan, lead author of the study and director of clinical services at the Foundation for Blood Research in Scarborough.

The research was published in the Journal of Medical Screening, a quarterly publication of the British Medical Journal. It builds on a study by the same researchers that was published in the New England Journal of Medicine last year. That study found that women with an underactive thyroid are more likely to have children with lower IQ scores.

The new study bolsters the idea that all pregnant women should be screened for an underactive thyroid, Allan said. Such testing would add $20 to $30 to the cost of routine prenatal bloodwork.

Treatment consists of taking a daily tablet of thyroid hormone to replace what the body refuses to make.