Well the lovely ladies of this forum have warned me (dozey first timer) that black pj bottoms will be very handy for disguising leakages in hospital.
Have been desperately searching, but hard to come by in the summer.
Found the holy grail today in Peacocks. Black jersey maternity pj bottoms, fiver. They have a wide roll over top waistband, like those very expensive yoga pants favoured by designer sportswear folk. So although they are sold as "maternity" they'll still fit non pg ladies (although I know that your tummy doesn't go flat straight away).
And also the sizing is massive, so despite being 30 weeks pg I have bought my first pair of size 10 trousers ever - am normally a 14!