Effects of vaginal progesterone administration on uterine contractility at the time of embryo transfer

To investigate whether uterine contractility at the time of embryo transfer (ET) can be reduced by early onset of luteal support with progesterone administered vaginally.

Prospective analysis.

Assisted reproduction unit. PATIENT(S): Eighty-four women undergoing 84 GnRH-a and FSH/hCG cycles for IVF-ET were studied. INTERVENTION(S): Vaginal progesterone was randomly started on the day of oocyte retrieval (group A, n = 43) or on the evening of ET (group B, n = 41). On the day of hCG administration and just before ET, 2-minute sagittal uterine scans were obtained by ultrasound and digitized with an image analysis system for assessing uterine contraction frequency. MAIN OUTCOME MEASURE(S): Uterine contraction frequency. RESULT(S): Whereas uterine contraction frequency was similar in both groups on the day of hCG (4.6 +/- 0.3 and 4.5 +/- 0.3 contractions per minute, respectively), only women in group A showed decreased uterine contraction frequency on the day of ET (2.8 +/- 0.2 vs. 4.2 +/- 0.3 contractions per minute). CONCLUSION(S): Vaginal progesterone administration starting on the day of oocyte retrieval induced a decrease in uterine contraction frequency on the day of ET as compared with preovulatory values. Uterine relaxation before ET is likely to improve IVF-ET outcome by avoiding the displacement of embryos from the uterine cavity.