(A) Mouse model: Naturally conceived embryos (Natural) were generated using B6/SJL male mice and CF-1 female mice, and IVF embryos were produced using capacitated sperm from B6/SJL mice and eggs from superovulated CF-1 mice. After embryo culture to the blastocyst stage, 10 blastocysts were transferred to pseudopregnant females. At E13.5, indicated by the arrow, pregnant females from both groups were euthanized, fetuses were collected by c-section, and fetal gonads were dissected for molecular analysis. At E18.5, pregnant females from both groups were c-sectioned, and fetuses were delivered and collected for molecular analysis. For adult cohorts, c-section–delivered pups at E18.5 (natural) or E19.0 (IVF) were fostered with WT dams and monitored until 12 or 39 weeks of age. Shown are (B) body weights before 6 hours fasting; (C) ovarian weights; (D) ovary to body weight ratios; (E) serum estradiol levels; and (F) progesterone levels assayed by ELISA. (G) The ratio of mtDNA relative to nDNA measured in whole ovarian DNA by RT-qPCR is depicted for all time points (see Methods for primers). Data are presented as the mean ± SEM, and sample sizes are indicated below each panel as the number of animals (litters). The black line represents the mean of each group. Normality was assessed using the Shapiro-Wilk test. Data that did not meet the normality assumption were analyzed using a nonparametric Mann-Whitney U test, whereas normally distributed data were analyzed using an unpaired 2-tailed t test with Welch’s correction. *P < 0.05 and **P < 0.01, for IVF groups compared with Naturals.