I couldn't bear to read the whole article and must confess I also haven't read the whole thread.
But for the brief period we employed a nanny (two actually, both wonderful and both with their own children, which is what made it affordable for us (the first one sadly had to leave us for a full-time post when her husband was made redundant)), I did live in fear of their deciding to have another child, as there was no way we could have afforded to pay mat pay for our nanny and childcare costs for DD on top.
DD went to nursery at 2.6 and both nannies subsequently went on to have lovely DC2s, so it's all good, but I can't pretend it wasn't a concern.