Pregnant wild-type and Akt1 nulls on C57BL/6 and CD1 genetic backgrounds were prepared, sacrificed on gestation days 10.5 (A), 14.5 (B), and 17.5 (C), and viable fetuses counted. Similar analyses were performed on CD1 Igf2 nulls. Bars represent the mean ± standard error of the mean (SEM). Numbers of litters evaluated are indicated. Values significantly different from controls are indicated with an asterisk (*P<0.05, **P<0.001).