The pup exchange test demonstrated that the reduced survival of pups lay entirely with dams. Pups were cross-fostered by sevoflurane-treated dams and control dams. (A) Six paired sevoflurane-treated and control dams that produced six to nine pups each were exchanged within 12 h after delivery. Pup survival rate was assessed for 6 days using 44 (born to sevoflurane-treated dams but nursed by control dams) and 45 pups (born to control dams but nursed by sevoflurane-treated dams). (B) Pups born to sevoflurane-treated dams had milk in the digestive tract (arrow) when nursed by control mice (Cont), whereas pups born to control dams had no milk in the digestive tract when nursed by sevoflurane-treated dams (Sevo).