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Why Pregnancy Sometimes Relieves Arthritis

(HealthCentersOnline) - Many women with inflammatory arthritis experience improvement during pregnancy because of fetal cells and DNA entering their bloodstream, scientists report.

Researchers at Fred Hutchinson Cancer Research Center in Seattle investigated why women with inflammatory arthritis often experience remission or improvement during pregnancy, followed by a flare-up within a few months after delivery. They studied 25 pregnant women: 17 with adult-onset rheumatoid arthritis (RA), six with juvenile idiopathic arthritis (JIA) and two with other forms of inflammatory arthritis.

Blood tests were performed during and after the pregnancies to measure the amount of cells and DNA from the fetuses that entered the mothers' bloodstreams. The women were assessed for changes in their arthritis while pregnant and three to four months after they gave birth.

Improvement or remission of arthritic symptoms was noted in 21 of the 25 volunteers, including all of the JIA patients. As their blood levels of fetal DNA rose, so did their chances of experiencing relief from arthritis. However, by the fourth month after delivery, 90 percent of those who showed improvement experienced a recurrence of arthritis, which coincided with a sharp drop in their blood levels of fetal DNA.

Among the four patients whose pregnancy did not relieve their arthritis, blood levels of fetal DNA were low or absent throughout their pregnancies.

The researchers described their study as the first to examine fetal DNA in pregnant RA patients. They called for larger-scale research to explore whether fetal DNA may have a role in treating inflammatory arthritis.

The study was published last month in Arthritis & Rheumatism.

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