In Vitro Maturation of Oocytes in Women at Risk of Ovarian Hyperstimulation Syndrome-A Prospective Multicenter Cohort Study

Objective In vitro maturation (IVM) is an artificial reproductive technology in which immature oocytes are harvested from the ovaries and subsequently matured in vitro. IVM does not require ovarian hyperstimulation and thus the risk of ovarian hyperstimulation syndrome (OHSS) is avoided. In this multicenter prospective cohort study we assessed the live birth rate per initiated in vitro maturation (IVM) cycle in women eligible for IVF/ICSI, but with an increased risk for OHSS. Furthermore, we followed women who were not pregnant after IVM and proceeded to a conventional IVF/ICSI cycle. MaterialsAndMethods We started 76 IVM cycles, with rFSH priming, in 68 patients. There were 66 oocyte retrievals, in which a total of 628 oocytes was collected. We incubated the immature oocytes for 24-48 hours and fertilized those that reached metaphase II by ICSI. Results 386 (61% oocytes) achieved metaphase II. The fertilization rate was 55%. We performed 59 embryo transfers (1.9 embryos per transfer) in 56 women, including 3 frozen embryo transfers. There were four ongoing pregnancies (5.3% per initiated cycle) leading to the birth of a healthy child at term. None of the patients developed OHSS. The ongoing pregnancy rate of the first conventional IVF/ICSI cycle after an unsuccessful IVM cycle was 44%, which was unexpectedly high. Conclusion We concluded that IVM led to live births but with low effectiveness in our study. Earlier reported IVM success rates are higher, which can be caused by a longer experience in these centres with the intricate laboratory process. However a possible selection bias in these studies cannot be ruled out. Furthermore IVM might have a beneficial effect on further IVF/ICSI treatment due to its “ovarian drilling” effect.