STUDY QUESTIONThe 13th European in vitro fertilization (IVF)-monitoring (EIM) report presents the results of treatments involving assisted reproductive technology (ART) initiated in Europe during 2009: are there any changes in the trends compared with previous years?SUMMARY ANSWERDespite some fluctuations in the number of countries reporting data, the overall number of ART cycles has continued to increase year by year and, while pregnancy rates in 2009 remained similar to those reported in 2008, the number of transfers with multiple embryos (3+) and the multiple delivery rates declined.WHAT IS KNOWN ALREADYSince 1997, ART data in Europe have been collected and reported in 12 manuscripts, published in Human Reproduction.STUDY DESIGN, SIZE, DURATIONRetrospective data collection of European ART data by the EIM Consortium for the European Society of Human Reproduction and Embryology (ESHRE); cycles started between 1st January and 31st December are collected on a yearly basis; the data are collected by the National Registers, when existing, or on a voluntary basis.PARTICIPANTS/ MATERIALS SETTING, METHODSFrom 34 countries (-2 compared with 2008), 1005 clinics reported 537 463 treatment cycles including: IVF (135 621), intracytoplasmic sperm injection (ICSI, 266 084), frozen embryo replacement (FER, 104 153), egg donation (ED, 21 604), in vitro maturation (IVM, 1334), preimplantation genetic diagnosis/screening (PGD/PGS, 4389) and frozen oocyte replacements (FOR, 4278). European data on intrauterine insemination using husband/partner's semen (IUI-H) and donor (IUI-D) semen were reported from 21 and 18 countries, respectively. A total of 162 843 IUI-H (+12.7%) and 29 235 IUI-D (+17.3%) cycles were included. Data available from each country are presented in the tables; total values (as numbers and percentages) refer to those countries where all data have been reported.MAIN RESULTS AND THE ROLE OF CHANCEIn 21 countries where all clinics reported to the ART register, a total of 399 020 ART cycles were performed in a population of 373.8 million, corresponding to 1067 cycles per million inhabitants. For IVF, the clinical pregnancy rates per aspiration and per transfer were 28.9 and 32.9%, respectively and for ICSI, the corresponding rates were 28.7 and 32.0%. In FER cycles, the pregnancy rate per thawing was 20.9%; in ED cycles, the pregnancy rate per transfer was 42.3%. The delivery rate after IUI-H was 8.3 and 13.4% after IUI-D. In IVF and ICSI cycles, 1, 2, 3 and 4+ embryos were transferred in 24.2, 57.7, 16.9 and 1.2%, respectively. The proportions of singleton, twin and triplet deliveries after IVF and ICSI (combined) were 79.8, 19.4 and 0.8%, respectively, resulting in a total multiple delivery rate of 20.2%, compared with 21.7% in 2008, 22.3% in 2007, 20.8% in 2006 and 21.8% in 2005. In FER cycles, the multiple delivery rate was 13.0% (12.7% twins and 0.3% triplets). Twin and triplet delivery rates associated with IUI cycles were 10.4/0.7% and 10.3/0.5%, following treatment with husband and donor semen, respectively.LIMITATIONS, REASONS FOR CAUTIONThe method of reporting varies among countries, and registers from a number of countries have been unable to provide some of the relevant data such as initiated cycles and deliveries. As long as data are incomplete and generated through different methods of collection, results should be interpreted with caution.WIDER IMPLICATIONS OF THE FINDINGSThe 13th ESHRE report on ART shows a continuing expansion of the number of treatment cycles in Europe, with more than half a million of cycles reported in 2009. The use of ICSI has reached a plateau. Pregnancy and delivery rates after IVF and ICSI remained relatively stable compared with 2008 and 2007. The number of multiple embryo transfers (3+ embryos) and the multiple delivery rate have shown a clear decline.