Seems like the correct translation is missing IS in the second part.
The child is big and the woman IS small.
Actually, the English sentence is fine without the second "is." Though, of course, if someone uses the second "is," it is likely to be an accepted translation.
This should be a grammatically possible ellipsis.
Otherwise it would be a general statement about children and women in general. Which would be quite strange even if true. We would formulate such a general statement normally in plural.