Losing the weight gained during pregnancy is a real struggle for many new mothers. But dropping just 10 pounds between pregnancies may help many women diagnosed with a dangerous complication during the first pregnancy to avoid a recurrence the second time around.

Preeclampsia, which is characterized by high blood pressure, protein in the urine and swelling, occurs in about 5 percent of American pregnancies every year.

It can be more systemic than just high blood pressure. It can affect the liver, kidneys and the body's blood clotting system, Dr. Dorothea Mostello told Reuters Health. It's one of the leading causes of maternal death in childbirth in the developed world, she added.

Mostello, based at the St. Louis School of Medicine, is lead author of a new study in the September issue of the journal Obstetrics and Gynecology.

Mostello and colleagues wanted to know if women could do anything to reduce their risk of a recurrence during a second pregnancy.

Previous research by the team showed that pre-pregnancy weight is one of the strongest risk factors for recurrence. Because other research suggests that losing even a small amount of weight offers health benefits, such as reduced risk of heart disease, they wanted to know if it would reduce the risk of preeclampsia too.

They analyzed the medical records of nearly 18,000 Missouri women who gave birth twice between 1989 and 2005 and developed preeclampsia during the first pregnancy.

Before their second pregnancies, 1417 of the women had weighed less than before their first, 8,783 had remained about the same, and 8,798 had weighed more. The women who maintained their weights were used as the control group.

Overall, about 16 percent of these Missouri women developed preeclampsia during their second pregnancies. Of the women who had lost weight between pregnancies, 13 percent had a recurrence while 15 percent of women who maintained their weight and nearly 19 percent of those who gained weight had a recurrence.

Small changes in maternal weight between pregnancies -- as little as 10 pounds for an average height overweight woman -- significantly alter the risk of preeclampsia recurrence, across all weight categories, the authors note.

If you are overweight and you lose weight, your rate (of preeclampsia recurrence) is as low as someone in the normal weight category, and if you are overweight and gain weight, your rate is as high as someone in the obese category. Similarly, if normal weight people gain weight they have as high a risk as overweight people, Mostello said.

Researchers don't know why some women develop preeclampsia and others don't. Being African American appears to be a risk factor, so is being overweight or obese. While a woman can't do anything about her genetics, she may be able to reduce her risk of a recurrence by modest, generally achievable degrees of weight loss before pregnancy, the authors conclude.

Few options exist for lowering a woman's risk of developing preeclampsia in her second pregnancy, the authors write. Losing weight between pregnancies is the most reasonable measure to meaningfully lower the risk, they conclude.

Most weight-loss programs can get you a 10 or 15 pound weight loss, Mostello said.

The findings also underscore the need for uninterrupted healthcare between pregnancies, Mostello said. This is the period where we can make a real difference, she said.

SOURCE: link.reuters.com/cyg77n Obstetrics & Gynecology September 2010.

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