Insulin-dependent diabetes and pregnancy in mice were induced largely as described40. Briefly, 8–10 week old wild type or Alx3 −/− female mice were treated with streptozotocin (Sigma-Aldrich, Madrid, Spain; 75 mg/kg, i.p.) for four consecutive days to destroy pancreatic islets. The rise in blood glucose levels after the injections was monitored with a glucometer (Glucotrend Soft Test System; Boehringer Ingelheim, Mannheim, Germany) using tail blood, and hyperglycaemia was controlled by subcutaneous implantation of sustained-release insulin pellets (LinShin, Toronto, Ontario, Canada). Stable recovery of blood glucose levels after pellet implantation was monitored regularly. After confirming that blood glucose levels were stable for 2–3 weeks, females were mated with non-diabetic wild type or Alx3 −/− male mice. Noon on the day in which a vaginal plug was found was considered to be day 0.5 of gestation. Blood glucose levels were monitored from this time on every three days. On gestation day 10.5, pregnant mice were killed by cervical dislocation and the embryos were extracted for analyses. As a control, a different group of streptozotocin-treated females received insulin pellets but were not mated to males. These non-pregnant females did not develop diabetes during a similar period of time. Islet destruction by streptozotocin was confirmed in histological sections of the pancreases processed for insulin immunofluorescence (Supplementary Fig. S3).