Ok. I don't think this is the central meaning, but I'll give it a go to see if I can avoid the prostitution and make a decent reading.
The poem draws on the imagery of nature and the cityscape, constructing a meditation on the nature of love that is fractured, like the pavements of the city, with unexpectedly beautiful images of flowering lilac.
The poem is set in the liminal spaces of the city - the 'alleys' and 'spaces between', and the 'roundabouts' that are on the way to somewhere else. In these spaces, human experience is physically and emotionally cold, characterised by girls 'shiver[ing] in April winds' and men and women making 'deals' and 'transactions'. The first of these lines evokes Eliot's 'Wasteland', which also makes reference to the emotional emptiness of modern urban space, and which also claims that April, the 'cruelest month' is 'breeding lilacs out of the dead land'.
However, this imagery of coldness and ugly desolation - 'sour earth' and gardens flourishing with litter instead of plants - is in startling contrast with the central image of the poem, the new mother with her baby, who, like the flowering lilac, proves that 'love ... will open for everyone'. Although the scene seems desolate and bleak, the mother's love simply exists, 'before love knows that it is love'. It is innocent, unlike the capitalist city with which it is juxtaposed.
I could go on, but my computer is running out of charge! 