Miranda may not know the first thing about christening gowns, but when it comes to taking baby Brady out for a spin, Sex and the City’s new mom is as savvy as Carrie on a Manolo Blahnik bender. The ergonomically correct Bugaboo Frog stroller was rolled out on the show Aug. 25 — and now parents are clamoring for the Dutch-produced carriage. But don’t ditch your old pram yet — there’s a waiting list. The stroller, whose light yet sturdy design and small, swiveling wheels are perfect for maneuvering Manhattan streets, won’t be available Stateside until year’s end. (In the meantime, check bugaboo.nl/us.) ”Miranda is part of a really discerning group of mothers,” says Bugaboo spokesperson Kari Boiler, who adds that the $699 strollers have been sent to expectant SATC moms Cynthia Nixon and Sarah Jessica Parker. ”They know what they want by the time they have children.” And it won’t wrinkle the outfit like a Baby Bjorn.