Running title: Long-term growth alterations in the IVF mice

Epidemiological studies have reported a higher incidence of growth disorders among newborns conceived by in vitro fertilization (IVF), suggesting that IVF may be disruptive to the process of embryonic and fetal growth. However, the long-term effects of IVF on the growth and molecular mechanisms remain unclear. Therefore, we evaluated the body weight of IVF mice from birth to the age of 1.5 yr. In addition, we analyzed gene expression of insulin-like growth factor 2 (Igf2), H19, Igf2 receptor (Igf2r), miR-483 and their DNA methylation status using RT-qPCR, Western blot and pyrosequencing. The results showed that when compared with the in vivo group, the body weight of IVF mice was significantly higher at birth, but lower at 3 wk; in addition, gene expression of Igf2 was significantly up-regulated with down-regulated expression of H19 and miR-483 in both liver and skeletal muscle. At the same time, there were significant differences in the DNA methylation rates of Igf2/H19 differentially methylated regions (DMRs) and the IGF2 protein expression between the two groups. In the IVF treatment group, the differences in growth and expression disappeared at 10 wk. However, at 1.5 yr of age, aberrant expressions of Igf2/H19, Igf2r, miR-483, and changes in DNA methylation rates in the liver or skeletal muscle were again observed in IVF mice. Our results indicate that IVF cause alterations in mouse growth during the postnatal periods that may be associated with alterations in Igf2/H19 expression and likely involve the regulation of miR-483 and the methylation status of Igf2/H19 DMRs. Summary sentence: IVF affects the weight of newborns as well as long-lasting changes in Igf2/H19 both in liver and skeletal muscle which may be associated with epigenetic mechanisms such as DNA methylation and miR-483.