Along with shopping for sippy cups and strollers, expectant parents may want to consider another task for their to-do list: honing their marriage skills.

Numerous studies have shown that a couples’ satisfaction with their marriage takes a nose dive after the first child is born. Sleepless nights and fights over whose turn it is to change diapers can leach the fun out of a relationship.

Now, a growing number of mental-health professionals are advising couples to undergo pre-baby counseling to hash out marital minefields such as divvying up baby-related responsibilities, money issues and expectations for sex and social lives. A growing number of hospitals, midwives and doulas (birth coaches who provide physical and emotional support) are teaching relationship skills alongside childbirth education classes.

About two-thirds of couples see the quality of their relationship drop within three years of the birth of a child, according to data from the Relationship Research Institute in Seattle, a nonprofit organization focused on strengthening families. Conflict increases and, with little time for adult conversation and sex, emotional distance can develop.

Men and women experience the deterioration differently: Mothers’ satisfaction in their marriages plummets immediately; for men, the slide is delayed a few months. Hormonal changes, the physical demands of childbirth and nursing, and an abrupt shift from the working world to being at home with an infant may explain that, says Renay Bradley, the director of research and programming at the Relationship Research Institute.

A key source of conflict among new parents is dividing up