Actually, I think a Sikh woman is more likely to preserve Sikhism when married to a muslim than vice versa.
Scenario: Its thundering outside and your child is having a nightmare...The muslim girl, would say "allah will not harm you, say mohammeds name, etc"...she will preach Islam to her child, and her child will turn toward Islam.
Same scenario, the Sikh woman would most likely calm her child in the religion she grew up in....saying waheguru etc, taking the kid to the gurdwara...she will expose Sikhism to her child without realizing herself.
Therefore, you learn most religious habits and values from your mother growing up....just a fact..