Study question: Are the obstetric and perinatal outcomes of deliveries following in vitro maturation (IVM) cycles different from births generated from controlled ovarian stimulation (COS) cycles?
Summary answer: The obstetric and perinatal outcomes of births from IVM cycles are comparable with those of ICSI treatments, including the incidence of major and minor abnormalities.
What is known already: Only few and numerically small reports on the health of IVM children are currently available.
Study design, size and duration: Retrospective cohort study involving 196 babies born from IVM cycles carried out with different priming regimens. Of these children, 79 developed from oocytes matured in vitro after 30 h of culture, while 104 originated from oocytes found mature and inseminated on the day of recovery. Thirteen babies were obtained from embryos developed from both types of oocytes. Data of these births were compared with those of 194 children born from COS ICSI cycles performed during the same period (March 2004 to December 2011).
Participants/materials, setting and methods: IVM cycles were done in the absence of gonadotrophin administration or with FSH and/or HCG priming. All oocytes were inseminated by microinjection. ICSI and ICSI cycles were chosen as a control group to exclude possible influences of the insemination technique. Couples in which maternal age was >39 years or affected by azoospermia were excluded to rule out major parental effects.
Main results and the role of chance: In single births, gestational age at delivery was comparable, but birthweight was significantly higher (P = 0.009) in children from IVM cycles (3091 ± 669 versus 3269 ± 619 g). In a separate analysis of the IVM group, comparing singleton births derived with certainty from oocytes matured in vitro (n = 71) or in vivo (n = 74), no statistically significant differences were observed in terms of birthweight (3311 ± 637 versus 3194 ± 574 g, respectively) and gestational age (38.9 ± 2.4 versus 38.4 ± 2.1 weeks, respectively). In twin births, gestational age was lower in IVM cycles, while weight at birth was comparable (ICSI, 2432 ± 540 g; IVM, 2311 ± 577 g). In single births, major and minor abnormalities were 2 (1.4%) and 6 (4.1%) in the ICSI group and 0 (0.0%) and 8 (5.2%) in the IVM category, respectively. In twin children, major and minor abnormalities were 1 (2.2%) and 2 (4.3%) in ICSI babies and 0 (0.0%) and 2 (4.6%) in IVM cycles, respectively.
Limitations and reasons for caution: The study is the largest conducted so far. Nevertheless, it is limited by its retrospective nature and the fact that most births of IVM treatments derived from oocytes found mature at recovery in cycles primed with HCG. A more comprehensive appraisal of the health status of IVM children will demand larger prospective studies.
Wider implications of the findings: The study is consistent with previous reports suggesting a possible role of standard ovarian stimulation in determining a reduced birthweight in children born from COS cycles.
Study funding/competing interest(s): No external funding was sought to support this work. The authors have no conflicts of interest to declare.
Trial registration number: Not applicable.