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Postpartum Uterine Regression Study (PUR)

Epidemiology Branch

Postpartum Uterine Regression Study (PUR)

The purpose of the Postpartum Uterine Regression Study was to investigate pregnancy-related change in fibroids. Study researchers hypothesized that if women had small fibroids prior to becoming pregnant those fibroids would tend to disappear while large fibroids would remain essentially unchanged in size. For more information, about the study population see our collaborating study website, "Right From the Start: A Study of Early Pregnancy Health" .


In epidemiologic studies of uterine fibroids, parity tends to be protective. The researchers hypothesized that a protective effect could arise from loss of early tumor lesions during postpartum remodeling of the uterus (Baird and Dunson, 2003). To test this hypothesis, the researchers developed a collaborative study with Kathie Hartmann at the University of North Carolina at Chapel Hill. In her miscarriage study, women enroll very early in pregnancy and have an ultrasound examination around the seventh gestational week. Hartmann searches for fibroids and records the size and location of any tumors. With NIEHS support, the women with fibroids were given another ultrasound examination 3-4 months after their pregnancy ended. Size and location of all fibroids were again recorded. Data suggesting that fibroids tend to disappear can encourage further investigation of the mechanisms involved and may lead to new strategies for non-surgical fibroid treatment.

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