Posted it above but I read about it in the book Expecting Better by Emily Oster. She cites this study https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.

Posted it above but I read about it in the book Expecting Better by Emily Oster. She cites this study https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006066.pub3/full https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD...