[Ten years of results of in-vitro fertilisation in the Netherlands 1996-2005].

Objective: To present the numbers and results of Dutch IVF treatment from 1996-2005 and to describe trends and differences between centres.

Design: Retrospective data-collection, description and analysis.

Method: The annual statistics from all Dutch IVF centres covering the years 1996-2005 were collected, described and analysed.

Results: During this period 138,217 IVF or intracytoplasmic sperm injection (ICSI) cycles were started and 14,881 transfers of frozen-thawed embryos (cryo transfers) were performed. The number of ICSI treatments, in particular, increased to more than 6000 cycles during this period. These treatments resulted in 30,488 ongoing pregnancies (22.1% per cycle started; 19.1% for IVF and 23.4% for ICSI). The ongoing pregnancy rate per cycle increased from 17.6% in 1996 to 24.4% in 2005. The increase after cryo transfers was remarkable (from 9.4% to 17.6%). It is estimated that during this period, about 1 in 52 newborns in the Netherlands was an IVF or ICSI child (1996: 1 in 77, 2005: 1 in 43). There were differences between the individual centres regarding the ongoing pregnancy rate per cycle (range: 15.0-26.4%), the percentage of ICSI (range 20-58%), the percentage of cryo transfers per cycle (range: 4-22%) and the multiple pregnancy rate (range 5-27% in 2005).

Conclusions: In the Netherlands the pregnancy rate has increased over the last 10 years as has the number of IVF treatments. Cryo transfers have become increasingly important and the multiple pregnancy rate has decreased. Although thanks to the collaboration of all centres, the current registry produces important data and works well, there are a number of limitations e.g. the retrospective nature with no validation, which must be tackled over the coming years.