Background Conventional in vitro fertilization treatment requires hormone ovarian stimulation to increase the numbers of mature oocytes retrieved. In in vitro maturation, immature oocytes are instead retrieved from unstimulated ovaries and matured in a laboratorium for 30 hours, before fertilisation. Approximately 400 children have been delivered following in vitro maturation. In Norway in vitro maturation of oocytes was granted conditional approval for the period 2004-2008. Norwegian authorities will in 2007 assess whether in vitro maturation of oocytes as a method within assisted reproduction will be permitted in Norway also in the future.

Mandate The Directorate for Health and Social Affairs has asked the Norwegian Knowledge Centre for the Health Services to summarize the documentation of the clinical outcome of IVM cycles and the obstetric, perinatal and devolopmental outcome of IVM children.

Methods We have performed a systematic search for literature in the following databases: Cochrane Library, Medline and Embase for the period 2004-2008.

Results We included 17 relevant publications that represent 8 unique datasets. Few studies were controlled and no RCTs were identified. These studies documented results from 182 IVM children. Two studies had follow-up data, but no studies had followed the children more than two years. Reported rates of spontaneous abortions varied between 17 and 63 %. Pregnancies per embryo transfer in the studies varied between 0 and 36 %. Alhough included studies reported that IVM children were healthy, and with normal development, further studies are needed to make conclusions regarding the impact of IVM on childrens' health and development.

Conclusion There are no relevant randomized controlled trials reporting clinical success or safety following IVM in assisted reproduction. Few children are born after IVM, and few studies with short follow-up-time have followed the IVM children.