I am amazed at the number of people, Catholics mind you, who see nothing wrong with scheduling a social event for a Sunday morning. True, I could go to Mass the evening before, early that morning or even Sunday evening, but that's not what I want to do. The Sabbath belongs to the Lord, and it is appropriate to honor Him on Sunday morning whenever possible.
Schedule the baby/wedding/engagement showers/parties/whatever for some other time than Sunday morning, particularly if you want me to RSVP yes. No?