The rationale for this trope is related to Babies Make Everything Better. Sequels to works with these sort of endings often make the kids into major characters. Might involve a Screaming Birth, but this is, of course, optional the baby itself is what makes this trope run, so the cuter the better. If the couple had a child early in the story, perhaps resulting in a Shotgun Wedding, this may result in a younger brother or sister. Her Heart Will Go On may entail the discovery that she is pregnant after the father is dead: he's gone, but he's left her Someone to Remember Him By. The Bittersweet Ending often shows a Dead Guy Junior in this situation.

The likelihood of this increases exponentially every time one or both people say they don't want to have a kid, or express reluctance to. Even if one or both were confirmed as sterile - such is The Power of Love. It seems that the Law of Inverse Fertility gets inverted once you get past the climax. And expect the newborns to be named after dead friends or teammates who had made Heroic Sacrifices during the course of the story, clearing the path for the heroes' victory at the cost of their own lives. (See also Hope Sprouts Eternal.) If the ending is not Cleaning Up Romantic Loose Ends, unmatched friends often appear in the role of Honorary Uncle conversely, Weddings for Everyone may result in loads of underfoot children. Grow Old with Me in an epilogue may feature grandchildren, or even great-grandchildren.

The older the children, obviously the more years have passed in peace, proving more of the 'Ever After' part of the happy ending. Generally a whole brood, as a mundane equivalent to Fertile Feet, or demonstrating that Mordor has No Ontological Inertia. Or, if we cut to the future, show them at home with their growing children. The answer? Skip ahead a bit to show the Happily Married couple.and their adorable new baby. Or, maybe, you just want to make things as adorable as possible. Maybe the Bittersweet Ending is short on 'sweet'. Perhaps you need some Dénouement to confirm that, yes, really, it really was happy. Maybe the marriage happened earlier in the season perhaps the couple was already betrothed but weren't able to consummate the union. Sometimes you have a Happily Ever After situation, but it just isn't heartwarming enough.

And Baby Makes Four by Penny Scott-fox