have babies and take time out of the workforce: all your male colleagues who you are no doubt equal to in qualifications and experience up until that point suddenly pass you by.
you return to the workforce a year or two later with a hole in your CV and knowledge and possibly quals and contacts that are 1 - 2 years behind where the industry is at that point.
Of course you will not reach the same heights as those that didn't take time out.
essentially it comes down tot he myth that everyone can have it all. In this case it is women - yes there seems to be a choice. Unfortunate but true.
