Placental abnormalities are associated with specific windows of embryo culture in a mouse model

Assisted Reproductive Technologies (ART) employ gamete/embryo handling and culture in vitro to produce offspring. ART pregnancies have increased risk of low birth weight, abnormal placentation, pregnancy complications, and imprinting disorders. We and others have previously shown that embryo culture induces low birth weight, abnormal placental morphology, and lower levels of DNA methylation in placentas in a mouse model of ART. We hypothesized that these adverse effects are linked to a subtle disruption of specific biological processes during preimplantation development. To test this hypothesis, we performed embryo culture for several discrete periods of preimplantation development and assessed fetal and placental outcomes at term. We observed a reduction in fetal:placental ratio in two distinct windows of preimplantation embryo development, while placental morphological abnormalities and reduced imprinting control region methylation were associated with culture prior to the morula stage. We also provide evidence that extended culture to the blastocyst stage induces additional placental DNA methylation changes compared to embryos transferred at the morula stage, and that female concepti exhibited a higher loss of DNA methylation than males. Altogether, this study identifies specific developmental windows of susceptibility and potential targets for embryo culture optimization. Mouse (Mus musculus) term placentas from 1-cell-morula group (n=12, 6 females and 6 males), 1-cell-blastocyst group (n=12, 6 females and 6 males) and Natural group (n=10, 5 females and 5 males) were analyzed.