It comes after letters were sent to a national farming body and the dairy giant Fonterra threatening to contaminate formula with a pesticide. About 30 women in the Northland region, on New Zealand's North Island, say they'd be happy to contribute, and some women have already started expressing their milk for babies who are ordinarily fed formula, the Northern Advocate newspaper reports . "It was a bit scary thinking that if something were to happen to the formula then the babies might not be okay," says Kelsie Brophy-Watts, an admin of a local mothers' Facebook group where the idea first appeared.