Although this doesn't address the original question, since the replys have concerned virginity and chastity in the 18th and 19th century, I thought this might be of interest to some of you. I found this in a post from searching out my roots.

More on premarital pregnancy and unmarried mothers: There is overwhelming evidence that pre-marital chastity was not particularly important to farming and labouring families in rural Devon ( and UK) in the 18th and 19th century - it was not considered important until much later in the 19th century, by which time middle-class values and Evangelical mores had spread widely throughout urban and rural communities . Illegitimacy was unacceptable, but it was extremely common for a bride to be pregnant on her wedding day. Apparently historians have calculated (no doubt by collating dates of marriage and dates of baptism of first born children) that more than half the brides in some English West-country districts in the 1830's went to the altar pregnant. (Ref: "Australians: A Historical Library - Australians 1838", Fairfax, Syme and Weldon Assoc., Broadway, NSW, 1988). The actual church ceremony was at this time less important as a sign of marriage than the initial commitment in the form of a promise or betrothal, which was often performed at home, before family members or other witnesses. A gift often sealed the arrangement. Couples often effectively started living together after this, and married when a child was on the way. Illegitimacy was more commonly a result of the breakdown of this common arrangement, than of promiscuous behaviour. Thus an unmarried mother had usually been promised marriage, but then was let down, abandoned or her betrothed died. In earlier centuries, jilted brides regularly appeared before the ecclesiastical courts to accuse their betrothed of breach of promise - this is because the promise of marriage made in the presence of others, as described above, was considered a binding agreement. The reason that brides were in their twenties when they became pregnant and then married was that a marriage was an economic arrangement, and required a certain amount of financial stability before it was undertaken. Hence a woman from a labouring or farming background often worked on the family farm, or as a servant on another farm, or in the town, and saved up for a number of years in order to be able to bring money or goods to the marriage, before she considered finding a partner. Once she was "promised" she became pregnant quite quickly, and pregnancy was the stimulus to become legallymarried. Teenage brides would have been fairly unattractive, as not only would they bring less domestic and farming skills to the marriage, but they would have less money or belongings to offer, as well. Very wealthy girls could afford to marry younger, of course.