1 Department of Pathology and 2 Centre for Reproductive Medicine, AZ-VUB, Laarbeeklaan 101, 1090 Brussels, Belgium
3 To whom correspondence should be addressed. e-mail: claire.bourgain{at}az.vub.ac.be
Dear Sir,
We read with interest the very thorough meta-analysis conducted by Pritts and Atwood (2002) on luteal phase support in infertility treatment. One of the authors conclusions was that supplementation with i.m. progesterone conferred the most benefit compared with oral or vaginal use.
In their meta-analysis, the authors included five studies judged evaluable in querying the best route for progesterone administration (i.m. or vaginal). In these trials, either vaginal gel (CrinoneTM) or vaginal cream preparations were used for supplementation.
We believe that it would be appropriate to include a sixth study by Smitz et al., (1992). This study was not mentioned in the article. In a prospective randomized trial, 262 patients were stimulated in a GnRH agonist long protocol and randomized for luteal support with i.m. progesterone (50 mg/day) or intravaginal micronized progesterone (600 mg/day), starting on the day preceding the oocyte retrieval. Study outcome showed no difference in clinical pregnancy rate (CPR) or implantation rate (IR) between groups, although there was a trend for higher CRP and IR in the group receiving intravaginal progesterone. Miscarriage rate was significantly lower in the intravaginally treated group.
We estimate that recalculation of the data including the above mentioned study might alter the conclusions stating a less beneficial fertility outcome with vaginal luteal phase support.
References
Pritts, E.A. and Atwood, A.K. (2002) Luteal phase support in infertility treatment: a meta- analysis of the randomized trials. Hum. Reprod., 17, 22872299.
Smitz, J., Devroey, P., Faguer, B., Bourgain, C., Camus, M. and Van Steirteghem, A.C. (1992) A prospective randomized comparison of intramuscular or intravaginal natural progesterone as a luteal phase and early pregnancy supplement. Hum. Reprod., 7, 168175.[Abstract]