Here's a link from Blood-Horse that clearly explains the 8/24/2005 Jockey Club Rule revision about late-in-the-calendar-year foalings:http://www.bloodhorse.com/horse-racing/articles/29657/jockey-club-rule-changed-inspections-possible-of-early-foalsIn other words, if a foal's birthdate is listed early in the calendar year, inspectors can go out to check on the foal to determine its actual foaling date. Any owner/breeder engaged in deceptive practices may be denied any/or all of the privileges of The American Stud Book.
Think this comment about sums it up . . ."While eavesdropping at the New Year's Eve party the lady in the blue silk dress heard that the neighbor down the way say he was hoping his bay mare would hold on for just a couple of more days before she dropped her chestnut colt with four white stockings."
From WinStar Farm facebook: First foal for FEDBIZ! His first reported foal, dark bay or brown filly, was born on Sunday, Jan. 3rd at Brandywine Farm in Paris, KY. Pictured is the filly with her dam, Exotic Bloom (Distorted Humor) and her breeder, Pam Robinson! https://scontent-ord1-1.xx.fbcdn.net/hphotos-xaf1/v/t1.0-9/1918261_10153506281488922_74625428434003384_n.jpg?oh=50fd8e0ad4e9b986edfbbc91ce60d641&oe=5717EF13