A randomized controlled trial in Blantyre, Malawi, found that a specific invitation to the men increased their attendance by 50%.
The trial involved 460 families, split into two equally sized groups. In the group that received invitations, 28% of men attended. In the control group, only 19% did.
Specifically inviting men to attend antenatal services is step 3 of the 10-point plan for father-inclusive practice that we recently published here.