Something that most couples do not consider when starting their lives together is the importance of a good beginning. The way in which you start a relationship can be the difference between comfort and added stress later on in the marriage. Just in the simple act of asking a father's permission before proposing can build a solid foundation of trust between in laws and between husband and wife. Many people don't realize the import of many steps in relationships. Such as who is present at the birth of a child, by sharing the experience only with those directly involved one can capitalize on an opportunity to bond and build relationships with children and spouse. Marital satisfaction tends to go down consecutively as each child is born.
Something most parents don't know is that a woman produces a considerable amount of oxytocin after she gives birth. Oxytocin is a bonding chemical, if a woman's mother, mother in law or sister is in the room when she gives off this chemical, then this time of intense bonding will be shared with the wrong person, a husband can use this to his benefit and counter act the separation that can occur if he is excluded. 
be aware of your actions, be aware of the possible consequences of excluding significant others from important moments and milestones in life.