Single Moms GUESTS: ANDREA ENGBER Author The Complete Single Mother (Adams Media, 2000) Founder & Director, National Organization of Single Mothers MARTIN O'CONNELL Chief, Fertility & Family Statistics Branch, Bureau of Census SARAH HOWARTH Single mother of 2 1/2 yr old twins V.P. Engineering for internet start-up Counseler, single mother-by-choice workshops FRAN TERNUS Attorney, non-profit firm in San Francisco Nearly eight million U.S. households are run by single moms-- that's a million more than a decade ago. While the number one cause for single-parent families is still divorce, a growing number of women are having children out of wedlock by choice. But they say going solo is as difficult as it is fulfilling. The stigma of being a single mother is easing, but are the struggles?