In this prospective cohort study of 286 women undergoing fresh embryo transfer after IVF, uterine contraction frequency and direction were measured before (-5 min), 5 min after (+5 min) and 60 min after (+60 min) embryo transfer. Mean ± SD uterine contraction frequency at -5 min was 1.8 ± 1.1 contractions per min, increasing significantly (P < 0.05) to 2.0 ± 1.1 at +5 min, and returning back to baseline 1.8 ± 1.1 at +60 min. At -5 min, the proportion of women the with retrograde, antegrade, indeterminate direction and absent contractions were 33%, 44%, 17% and 6%; at +5 min, 40%, 42%, 13% and 5%, and at +60 min, 42%, 38%, 14% and 6%. No significant change was observed in the proportion of direction at these three time points. Logistic regression analysis showed live birth rate was significantly reduced in older women (P = 0.035) and in those with higher uterine contraction frequency at +5 min (P = 0.006). Frequency of uterine contraction immediately after embryo transfer (+5 min) seemed to be a significant predictor of IVF outcome and may help to identify women who could benefit from the use of muscle relaxant therapy to improve outcome.
Keywords: contraction direction; contraction frequency; embryo transfer; pregnancy rate; uterine contractions.
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