I wouldnt be too happy either tigwig to be honest. Theres also the possibility that when heavily pregnant you may not be able to cope with childminding? what about hospital appts? if you had morning sickness?
As bednobs says at the very least youll need 2 weeks off, fair enough that could be same if you were to have a holiday, parents would need alternative plans. But will you be able to cope with childminding AND looking after a newborn?
is there any way you can get a job in a nursery instead? or start a small creche up with a few other childminders so that you have enough cover?