Berahino has joined Northampton on a one-month loan deal. The England Under-20 international signed a new one-year contract with West Brom in the summer.
“Saido is a player that I feel has got the quality and the finishing power to help us,” said Northampton boss Gary Johnson.
“West Brom think very highly of him and I have seen him play a couple of times for their reserves.
“He is a good player and you don’t play for England at Under-20 level if you haven’t got something about you. He is quick and strong and he is exactly what we need at the moment.”