Elevated serum interleukin-1β levels and interleukin-1β-to-interleukin-1 receptor antagonist ratio 1 week after embryo transfer are associated with ectopic pregnancy

Objective To investigate whether interleukin-1β (IL-1β) and interleukin-1 receptor antagonist (IL-1RA) serum levels in the early luteal phase differ in IVF cycles that result in an ectopic pregnancy (EP) when compared with other outcomes. Design Retrospective cohort. Setting Not applicable. Patient(s) A total of 307 women whose serum samples were available, with the following IVF outcomes: 103 live births, 80 negative pregnancy tests, 52 biochemical pregnancies, 47 EPs, and 25 miscarriages. Intervention(s) Serum samples were obtained on cycle days 24 and 28 (cycle day 14 = day of egg retrieval). Levels of IL-1β and IL-1RA were determined by quantitative ELISA performed by blinded personnel. Main Outcome Measure(s) IL-1β and IL-1RA levels, IL-1β-to-IL-1RA ratio versus cycle outcome. Result(s) The IL-1β levels were predictive of an EP. At cycle days 24 and 28 the mean IL-1β levels were higher in patients with an EP (127.1 pg/mL and 166.9 pg/mL, respectively) than in women with any other IVF outcome (15.8-55.3 pg/mL and 14.8-75.5 pg/mL, respectively). At cycle day 24 the IL-1β-to-IL-1RA ratio was 0.18 in the ectopic group versus 0.01-0.09 in the other groups. Conclusion(s) Elevated IL-1β levels and IL-1β-to-IL-1RA ratio as early as 4 days before the first pregnancy test are associated with an EP. If confirmed by prospective studies, clinical application of these findings could potentially improve EP detection.