Glucose levels were measured with a glucometer using blood obtained by puncture of the tip of the tail after an overnight fasting period. After measuring baseline glucose levels, mice were injected with glucose (2 g/kg, i.p.), and blood was tested 15, 60 and 120 minutes after the injection. Glucose tolerance tests were carried out both before pregnancy and 8.5 days after coitus. Fasting (4 hours) serum insulin was measured before pregnancy and 10.5 days post coitus using an ELISA kit (Crystal Chem, Downers Grove, IL, USA).