The human microbiome includes trillions of bacteria, many of which play a vital role in host physiology. Numerous studies have now detected bacterial DNA in first-pass meconium and amniotic fluid samples, suggesting that the human microbiome may commence in utero. However, these data have remained contentious due to underlying contamination issues. Here, we have used a previously described method for reducing contamination in microbiome workflows to determine if there is a fetal bacterial microbiome beyond the level of background contamination. We recruited 50 women undergoing non-emergency cesarean section deliveries with no evidence of intra-uterine infection and collected first-pass meconium and amniotic fluid samples. Full-length 16S rRNA gene sequencing was performed using PacBio SMRT cell technology, to allow high resolution profiling of the fetal gut and amniotic fluid bacterial microbiomes. Levels of inflammatory cytokines were measured in amniotic fluid, and levels of immunomodulatory short chain fatty acids (SCFAs) were quantified in meconium. All meconium samples and most amniotic fluid samples (36/43) contained bacterial DNA. The meconium microbiome was dominated by reads that mapped to Pelomonas puraquae. Aside from this species, the meconium microbiome was remarkably heterogeneous between patients. The amniotic fluid microbiome was more diverse and contained mainly reads that mapped to typical skin commensals, including Propionibacterium acnes and Staphylococcus spp. All meconium samples contained acetate and propionate, at ratios similar to those previously reported in infants. P. puraquae reads were inversely correlated with meconium propionate levels. Amniotic fluid cytokine levels were associated with the amniotic fluid microbiome. Our results demonstrate that bacterial DNA and SCFAs are present in utero, and have the potential to influence the developing fetal immune system.

Is in vitro maturation (IVM) as successful as standard in vitro fertilization (IVF) for the treatment of patients with polycystic ovaries (PCO) in terms of fresh, frozen and cumulative pregnancy outcomes? There was no difference in clinical pregnancy rates in fresh or frozen embryo transfer (FET) cycles between the two treatment groups however, the IVM group showed a lower clinical pregnancy rate cumulatively. There was significantly fewer live births resulting from IVM treatment for both fresh and cumulative cycle outcomes however, there was no difference in live birth rates resulting from FETs between IVM and IVF treatment. IVM is well recognized as the only treatment option to eliminate completely the incidence of ovarian hyperstimulation syndrome. However, historically IVM has been less successful than standard IVF in terms of clinical pregnancy, implantation and live birth rates. This paper represents a retrospective case–control study. The study involved 121 participants who underwent 178 treatment cycles. Cycles were completed between March 2007 and December 2012. All fresh cycles and subsequent FET cycles were included in the analysis to calculate cumulative outcomes. All participants were prospectively diagnosed with PCO morphology or polycystic ovarian syndrome (PCOS) and underwent either IVM or standard IVF treatment. Their treatment outcomes were analysed with regard to embryological data, and the rate of biochemical pregnancy, clinical pregnancy and live birth, in addition maternal and neonatal outcomes were assessed. Fifty-six patients underwent 80 cycles of IVM treatment and 65 patients underwent 98 cycles of standard IVF treatment. For fresh cycles, the differences in the biochemical pregnancy, clinical pregnancy or miscarriage rates between the two treatment groups were not statistically significant. The IVM group showed significantly lower live birth rates in fresh cycles in comparison to standard IVF treatment (18.8 versus 31.0%, P = 0.021). For frozen embryo transfer (FET) cycles the differences in biochemical pregnancy, clinical pregnancy, live birth or miscarriage rates between the two treatments groups were not statistically significant. The cumulative biochemical pregnancy (67.5 versus 83.7%, P = 0.018), clinical pregnancy (51.3 versus 65.3%, P = 0.021) and live birth rates (41.3 versus 55.1%, P = 0.005) were significantly lower in the IVM group in comparison to the standard IVF treatment group. There was no overall difference in the cumulative miscarriage rates between the two treatment groups. There was no difference between treatment methods with regard to the neonatal outcomes, and the IVM group had a significantly lower rate of ovarian hyperstimulation syndrome (0 versus 7.1%, P < 0.001). This was an observational study and further randomized clinical trials are required to clarify the difference in outcomes between standard IVF and IVM for patients with PCO/PCOS. This is the first study to compare IVM with standard IVF in PCO/PCOS patients using blastocyst development and single embryo transfer. Furthermore, it is the first study to show the results of fresh, frozen and cumulative treatment cycle outcomes between the two groups. Our results show similar success rates to those reported from other groups, particularly in relation to the incidence of miscarriage in fresh IVM cycles and improved success from FET cycles. Maternal and neonatal outcomes are consistent with the limited literature available. The study was supported by the Women's and Infant's Research Foundation of Western Australia. Professor Hart is Medical Director of Fertility Specialists of Western Australia (FSWA) and a shareholder Western IVF. He has received educational sponsorship from MSD, Merck-Serono and Ferring Pharmaceuticals. T.H. is a consultant with FSWA and a shareholder in Western IVF. She has received educational sponsorship from MSD, Merck-Serono and Ferring Pharmaceuticals. The other authors have no competing interests.