To celebrate its new Park Slope home and 9 years in the neighborhood, Birth Day Presence, which offers doula services and childbirth classes, is holding a party on Saturday from 11 am to 2:30 pm with a full slate of fantastic talks, demos and giveaways. Learn the best methods for pre-and post-natal exercise (11 am); the top 3 pain-relief techniques for labor (11:30); the baby gear you really need to buy (11:45); how to wear those free-form baby wraps (12:15); what doulas do (12:45); practice tummy time (1); treat your kids to puppetry (1:30), enter a raffle for a Maclaren stroller & more (2pm) and get free snacks from Tea Lounge and La Bagel Delight throughout. 182 8th Avenue, parlor floor, btwn Garfield and 1st St.