I'm not sure what sort of 'leak' you mean but no it's not normal. If you're referring to urinary incontinence this is fairly common after childbirth and some women do put up with it as a 'natural consequence' and some medical professionals seem to have this attitude that it's a normal part of being a woman (in toilets in the UK we're bombarded with signs that up to half of all women suffer from some problem of this sort) but it's not normal and it's not acceptable, if she's suffering from urinary incontinence she should first of all try pelvic floor exercises, they can take a few months before she'll see any improvement, if that doesn't help she should go to her doctor and insist she gets help.