Wood (3-3) retired the first 12 Houston batters before allowing a J.D. Martinez single to begin the fifth. The left-hander ended up allowing three hits, didn't issue a walk and struck out four.
Wood turned in his third consecutive strong start, yielding only one run on 12 hits over 20 2/3 innings during the span.
Jeff Baker delivered a two-run double and Anthony Rizzo added a run-scoring single to supply Chicago's offense.
Astros starter Wandy Rodriguez (6-6) absorbed the loss, yielding three runs on five hits over seven innings.