Analysis of factors associated with multiple pregnancy in an oocyte donation programme.

The aim of this study is to identify the factors associated with multiple pregnancy in an oocyte donation programme. A retrospective study (2000-2007) of 945 synchronous cycles was performed. Two embryos were transferred in all cycles on day 2 after oocyte retrieval. All variables (egg donor and recipient age, number of inseminated oocytes, fertilized oocytes, cleaved embryos, good-quality embryos available, good-quality embryos transferred and frozen embryos) were analysed in relation to the clinical pregnancy rate per transfer (PR) and the multiple pregnancy rate (MPR). The donor age was 26.8±4.5 years and recipient age was 41.0±5.4. The number of good-quality embryos per recipient was 3.1±2.5. The PR was 55.1% and the MPR 36.5%. The number of good-quality embryos transferred (2 versus 0) was significantly associated (P<0.05) with the PR (60.6% versus 43.5%). The relationship between the MPR and the number of good-quality embryos transferred was adjusted by donor and recipient's age. For those patients who received 2 versus 0 good-quality embryos, the odds ratio of a multiple pregnancy was 2.1 (95% CI 1.121-3.876). The only predictive factor for multiple pregnancies in an oocyte donation programme is the quality of the transferred embryos. Since the development of assisted reproduction techniques, most countries have witnessed increased rates of multiple pregnancy. In IVF/intracytoplasmic sperm injection, effective strategies must be established to prevent multiple pregnancy without reducing overall pregnancy rates. In oocyte donation programmes, there is less awareness about the related risks. Actually, a minimum of two embryos are still transferred in most centres. The patient's age is higher and this fact implies more obstetric and perinatal complications. The aim of this study is to identify the factors associated with multiple pregnancy to contribute to establish future guidelines to avoid those risks.