P26.03: Perinatal outcomes in singleton pregnancies conceived by natural cycle as compared with conventional IVF and spontaneously conceived pregnancies

Abstract

Worse perinatal outcomes associated to in vitro fertilisation (IVF) could be related to infertility per se, laboratory procedures and/or effects of ovarian stimulation. Natural cycle (NC) IVF permits to investigate the effect of IVF avoiding ovarian stimulation. Our objective was to assess the impact NC IVF on perinatal outcomes. Retrospective cohort study of singleton live births born from 2006 to 2016 in pregnancies obtained by NC IVF (n=71), conventional IVF (n=659), SC pregnancies in infertile (SC-I, n=194) and fertile (SC-F, n=136) couples. NC and conventional IVF pregnancies were obtained after a fresh transfer of cleavage stage embryos. Statistical comparisons were adjusted by maternal age. While IVF presented lower birthweight, NC showed similar birthweight (SC-F 3398g (394) vs SC-I 3260g (513) vs NC 3278g (493) vs IVF 3125g (517)*, p<0.001), birthweight centile (SC-F 50% (27) vs SC-I 55% (32) vs NC 51% (33) vs IVF 43% (31), p=0.004) and prevalence of low birthweight (SC-F 0.7% vs SC-I 7.2% vs NC 7% vs IVF 10.3%, p=0.004) as compared to SC. All infertile groups were associated with lower gestational age at delivery (SC-F 40.0 weeks (1.2) vs SC-I 39.0 weeks (3.1)* vs NC 39.3 weeks (1.4)* vs IVF 39.0 weeks (1.9)*, p<0.001) and higher prevalence of prematurity (SC-F 0.7% vs SC-I 5.7% vs NC 4.2% vs IVF 7%, p=0.04). This study shows preserved fetal growth in NC compared to conventional IVF. Future studies are warranted to better define the potential beneficial effect on perinatal outcomes associated to NC IVF.