Who were Dr. Hook & the Medicine Show singing about in 1972?

"Sylvia's Mother" is a 1972 single by Dr. Hook & the Medicine Show and the group's first hit song. It was written by Shel Silverstein, produced by Ron Haffkine and was highly successful in the United States, reaching #5 on the 'Billboard' singles chart (tied with "Sexy Eyes" from the album "Sometimes You Win" for the band's best performing song), as well as #1 in Ireland and #2 in the United Kingdom.

Dr. Hook & the Medicine Show (shortened to Dr. Hook in 1975) was an American rock band, formed in Union City, New Jersey. They enjoyed considerable commercial success in the 1970s. The band had eight years of regular chart hits in the United States, where their music was played on top-40, easy listening, and country music outlets, and throughout the English-speaking world including the UK, Canada and South Africa.