Well, irony is something that happens, which is the opposite of what was expected.

In story one, the irony is that the nightgown was in two places where birth was given.

In story two, there is no irony because obviously if she put the bab y in a milk tin, where else would she give the milk tin to other than the milk boy?

Last, in story three, the irony is that the maid is able to take care of other people’s kids while killing her own, which if she takes care of other’s kids, then she SHOULD like kids, and maybe want to have her own, but instead she is killing her own…..that’s messed up.

This is perhaps a more difficult question than you realize, because even the dictionary ties itself in knots trying to define what irony is. But it refers to the reader’s (hearer’s) perception that two or more associated facts have implications that are either contradictory in meaning or moral value, or more similar than first meets the eye. People wise in the ways of the World appreciate irony because it so often illustrates the way things actually are as opposed to the carey-sharey fantasy that social engineers – the apostles of “Political Correctness” – would have us believe.

I have no idea of what your first example means. The second implies that the milk boy gave the girl a baby in the course of his rounds, and she gave it back to him – also in the course of his rounds. (This is irony at its very best.) The third example, although grotesquely exaggerated, could be an ironic allusion to “day care.”