ELEVATED 1ST-TRIMESTER SERUM RELAXIN CONCENTRATIONS IN PREGNANT-WOMENFOLLOWING OVARIAN STIMULATION PREDICT PREMATURITY RISK AND PRETERM DELIVERY

Objective. To determine whether ovarian stimulation would result in hi gher circulating relaxin concentrations and whether this hyperrelaxine mia would be associated with prematurity. Methods: Two groups of women were studied: 1) women achieving pregnancy after ovarian stimulation (n = 114) and 2) women achieving pregnancy without treatment (n = 37). Serum was obtained at 6-12 weeks' gestational age; fetal number was d etermined by transvaginal ultrasound. Prematurity risk or preterm deli very was determined from the obstetric record. A specific human relaxi n enzyme-linked immunosorbent assay was used to measure serum relaxin concentrations. Hyperrelaxinemia was defined as levels greater than 3 standard deviations above the weighted mean of levels in normal unstim ulated singleton pregnancies at 6-12 weeks' gestation. Results: An ass ociation was found between prematurity risk or premature delivery and peripheral relaxin concentrations during weeks 6-12 of pregnancy in wo men having ovarian stimulation and in women having multiple gestations . Circulating relaxin concentrations greater than 16 ng/mL in women ha ving ovarian stimulation and levels greater than 7 ng/mL in women who had multiple gestations predicted prematurity risk or premature delive ry in 50% of the women. Conclusions: These data demonstrate that after ovarian stimulation, some women have highly elevated circulating firs t-trimester relaxin concentrations. First-trimester hyperrelaxinemia i dentifies a group of women at risk for prematurity who can be monitore d aggressively.