Induced wormholes due to quantum effects of spherically reduced matter   in large N approximation
  Using one-loop effective action in large N and s-wave approximation we discuss the possibility to induce primordial wormholes at the early Universe. An analytical solution is found for self-consistent primordial wormhole with constant radius. Numerical study gives the wormhole solution with increasing throat radius and increasing red-shift function. There is also some indication to the possibility of a topological phase transition. 
S. Nojiri, O. Obregon, S.D. Odintsov, and K.E. Osetrin