Breastfeeding’s big kids are coming out of the closet.

Collins Avenue, the production company behind “Dance Moms” and “American Stuffers,” is developing a reality series based on mothers who breastfeed older children — prompting local moms to speak up about the subject.

“I didn’t set out to nurse a 3-year-old,” said Jessica Cary of Park Slope, whose daughter Olive continues to breastfeed. “But two years came and went. Now breastfeeding and mothering are so intertwined for me.”

Government agencies don’t track breastfeeding past 12 months, and many pediatricians assume it has stopped by the child’s first birthday. So there’s no way to know how many of the 28 percent of New York babies who breastfeed up to age 1 keep on going.

Long-term breastfeeding moms often cite the World Health Organization, which encourages nursing until at least age 2. Neither WHO nor the American Academy of Pediatrics sets an upper limit on breastfeeding’s duration

“Experienced pediatricians realize that the benefits of breastfeeding don’t just magically disappear after one year,” said Karen McGratty, a lactation consultant in Midwood who is nursing her 3-year-old son.

Most mothers of breastfeeding preschoolers let the child take the lead in weaning.

“At this point I don’t offer nursing, only give it to her when she requests it,” said Cary. That leads to a gradual reduction on the child’s own timetable.

“You can’t force a child to breastfeed,” said one mother whose daughter self-weaned at age 7 and who asked not to be named so her child would not be subjected to schoolyard taunts. “If she’d wanted to stop any earlier she just would have.”