where are you looking ?
If its the full index, organised by the Years's Quarters, it might be a long trawl ....
it helps if you know the date of birth of the first child - start there and work back, not foolproof, but better than starting in say 1911 and working forward for the marriage .
The Quarters are indexed by first and last name on the page - which can get tangled if there are handwritten additions ....