In vitro fertilisation and gamete intrafallopian transfer: an integrative analysis of research, 1987-1992

To provide a statistically integrated analysis and review of all published outcome studies of in vitro fertilisation (IVF) and gamete intrafallopian transfer (GIFT) occurring in English language journals between 1987 and 1992; to provide information regarding outcome of assisted reproduction not otherwise available from national registers; and to assess correspondence of these outcomes with outcome data presented in the national registers of the Fertility Societies of Australia and the United States.

Computer literature review and manual search of major infertility journals to identify all papers reporting clinical pregnancy rates for IVF and GIFT. A secondary analysis of three factors, including 1. treatment (IVF vs GIFT), 2. stimulation protocol [combinations using clomiphene citrate (CC), combinations using gonadotrophin agonists (GnRHa), and combinations using neither clomiphene citrate nor gonadotrophin agonists, (designated by the symbols and acronyms approximately CC approximately GnRHa throughout this article)], and 3. cause of infertility, assessed their impact upon three clinical pregnancy rates: 1. cycles commenced, 2. cycles reaching retrieval and 3. cycles reaching oocyte/embryo transfer, via a series of one-way analyses of variance with either planned contrasts or post hoc comparisons.

The unit of observation was the published study. Data were obtained from 31 journals and 216 papers, containing 509 samples and 39,754 per cycles commenced. Data from the national registers of the Fertility Societies of Australia and the United States were used for comparison of literature-based outcomes, where appropriate.

The concordance between the outcomes reported in the national registers of Australia and the United States and the amalgamated literature-based data was such that cautious confidence was placed in the results of the subsequent analyses of the literature-based data which provided information not otherwise available. GIFT resulted in significantly more clinical pregnancies than IVF for each stage of the treatment cycle. Differences in pregnancy rates between IVF and GIFT were 8.6% more pregnancies for GIFT for cycles commenced, 14.2% for cycles reaching retrieval, and 7.5% for cycles reaching oocyte or embryo transfer. Stimulation protocols using gonadotrophin agonists (GnRHa) resulted in more clinical pregnancies than protocols using clomiphene citrate for each stage of the treatment cycle: from commencement (10.22%), to retrieval (8.36%), and to transfer (9.36%). Interaction effects indicated that GIFT-GnRHa combinations were superior to IVF-clomiphene citrate combinations for all rates. For cycles reaching retrieval and transfer, GIFT-GnRHa resulted in significantly more clinical pregnancies than IVF-GnRHa. GIFT-clomiphene citrate was better than IVF-clomiphene citrate and IVF-GnRHa was better than IVF-clomiphene citrate. Women with endometriosis (Stages I or II) achieved higher rates of clinical pregnancy than participants with other causes of infertility.

Significantly higher pregnancy rates for GIFT and GnRHa were demonstrated in this study. It was argued that since the differences in clinical pregnancy rates were smaller between IVF and GIFT when a GnRHa protocol was employed, the apparent superiority of GIFT may in fact be due, at least in part, to GnRHa. This question needs further prospective investigation. Women with endometriosis (Stage I or II) achieved higher pregnancy rates than those with other causes of infertility. Overall, this study provides confirmation that well-held clinical conclusions have a true basis in the published literature and that the published literature reflects population data reported in national registers. Further prospective research is needed to clarify the unique probabilities of a live birth for individual couples.