Human chorionic gonadotrophin priming for fertility treatment with in vitro maturation

Background In vitro maturation (IVM) is a fertility treatment that involves the transvaginal retrieval of immature oocytes, and their subsequent maturation and fertilisation. Although the live birth rate is lower than conventional in vitro fertilisation (IVF) with ovarian stimulation, it is a useful treatment, as it avoids the risk of ovarian hyperstimulation syndrome (OHSS). Women with polycystic ovaries (PCO) or polycystic ovarian syndrome (PCOS) are at an increased risk of OHSS. Thus, IVM may be a more useful treatment in this patient group. Strategies to maximise the maturation rates of the immature oocytes are important. This review focuses on the administration of human chorionic gonadotrophin (hCG) prior to immature oocyte retrieval. Objectives To determine the effectiveness and safety of hCG priming in subfertile women who are undergoing IVM treatment in the context of assisted reproduction. Search methods We searched the following electronic databases up to 29 August 2016: Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, CENTRAL, MEDLINE, Embase, PsycINFO, and CINAHL. We also searched the trial registries ClinicalTrials.gov and WHO ICTPR to identify ongoing and registered trials. We sought recently published papers not yet indexed in the major databases, and reviewed the reference lists of reviews and retrieved studies as sources of potentially relevant studies. There were no language restrictions. Selection criteria We included randomised controlled trials (RCTs) that compared hCG priming with placebo or no priming in women undergoing IVM. We also included RCTs that compared different doses of hCG, or the timing of oocyte retrieval. The primary outcomes were live birth rate and miscarriage rate per woman randomised. Data collection and analysis Two review authors independently selected studies for inclusion, and with a third author, assessed risk of bias and extracted data. We contacted the original authors where data were missing. For dichotomous outcomes, we used the Mantel‐Haenszel method to calculate odds ratios (OR). For continuous outcomes, we calculated the mean differences (MD) between treatment groups. We assessed statistical heterogeneity using the I² statistic. We assessed the overall quality of the evidence using GRADE methods. Main results We included four studies, with a total of 522 women, in the review. One of these studies did not report outcomes per woman randomised, and so was not included in