Women with the immune disease lupus who become pregnant face a much higher risk of serious complications and even death, U.S. researchers reported on Saturday.

Their findings confirm evidence that suggested pregnancy is dangerous for women with lupus, a chronic illness in which the immune system malfunctions to cause a range of symptoms including arthritis, fever, rash, hair loss, anemia and kidney failure.

The team at Duke University Medical Center in North Carolina studied more than 18 million hospital stays related to pregnancy and found that women with systemic lupus - the most common and severe form - had 20 times the risk of pregnancy-related death compared with women without the disease.

The disease also raised the risk of pregnancy complications such as blood clots and anemia.

“Pregnant women with lupus should never try to go through their pregnancy alone and simply hope for the best,” said Dr. Megan Clowse, who led the study to be presented at a meeting in Washington of the American College of Rheumatology.

The Lupus Foundation of America estimates that about 1.5 million Americans - 90 percent of them women - have some type of lupus.

All women with systemic lupus, pregnant or not, have a higher-than-normal risk of death, but pregnancy appears to worsen the risk.

Clowse’s team found that between 2000 and 2002, 13,500 women with systemic lupus gave birth and 44 of the women, or 0.3 percent, died.

Extrapolating this to the general population would translate to 325 deaths per 100,000 women - compared to the normal rate of 14 pregnancy-related deaths per 100,000 women, the researchers said.

“We don’t want these results to scare women with lupus away from getting pregnant, especially if they have a mild form of the disease,” Clowse said in a statement.

“But these women really must plan their pregnancies. They may need to change their medications before they get pregnant, and they really shouldn’t conceive when their lupus is active.”