The act of sex, up to a certain point in history, was reserved as a symbolic act of marriage and foremost to produce offspring. Sex was often a lackluster task that was expected from both husband and wife. In a loveless marriage, I would imagine it was like this:
For a man: Go to work, work, come home to dinner on the table, read a book while the wife put the kids to bed, have sex, sleep….repeat.
For a woman: Cook breakfast, tend to the kids, clean around the house, do laundry, prepare dinner, get the kids in bed, have sex, sleep….repeat.
I put it like this to help illustrate that sex, while fun (maybe–I would imagine this varies case by case), was a chore. It was an expectation of marriage. It wouldn’t be until the 1900’s when couples chose marriage and sex by who they loved, not because your neighbor was raising a child around your age.  As the century turned and sex started to become the passionate and love-making sex that it has become today, couples started to not only marry for love but see love as an acceptable reason to partake in premarital sex. With the start of the 1900’s, especially around 1920, the rate of pregnant brides started to rise again. In the roller-coaster of ups and downs in America’s sexual practices, America was headed back to the top!
Brides were once again showing up pregnant at the altar as shotgun weddings were on the rise. While there are many possibilities to explain the increase in this, I believe it started with a change in dating customs. For hundreds of years, dating (or courtship) “took place in the highly decorated home of the woman, in the company of her family. However the lower and middle class families couldn’t afford the fancy decor and opted instead for more public courtings.”  Public dating gave young couples privacy, away from peering eyes, to get into all types of shenanigans. At the turn of the 20th century, people were also starting to live alone. With cities starting to grow, both men and women were living on their own before marriage. This also gave couples private time for sex. For those unable to steal away to their private abodes, cars would become the new place to have sex. Still today, as it was one-hundred years ago, cars are on the top of the list as to where teens had sex for the first time.
The places to have sex were boundless and the price of condoms (as well as other forms of contraception) were exceptionally cheap. From 1890-1920, the average age of grooms and brides dropped.  This statistic correlates with the fact that pregnant brides and shotgun wedding rates were on the rise. (As were illegal abortions and sales of contraception.)
While the previously mentioned events definitely played a part in pregnancies, women’s independence played a large role as well. Women, who for thousands of years were not more than property, began to see a little fairness and were seeing the light at the end of the tunnel regarding rights. The women’s suffrage movement and the events leading up to the Nineteenth Amendment gave women options and a voice. Women were no longer seen as property. With their newfound confidence, they took control of their bodies and did with them what they deemed fit. Women now had freedom and independence; however, there was still a double standard that a “lady” should follow.
Numbers…gross, I hate this stuff! There are numbers, charts, and graphs that conclusively show that much changed in the 1900’s.  Most of the data does not start until the 60’s-70’s, but there is a pattern starting there that cannot be ignored. For instance, there is a direct correlation in the drop of shotgun weddings and the increase in child births to unmarried mothers. A chart from the CDC shows that pregnant brides at the altar dropped drastically from the 1960’s to the 1980’s.  Coincidentally (or probably not) there is a major rise in the births to unmarried mothers during the same time frame. 
Unmarried births have soared. In 1970, the number was 11% of live births were to unmarried mothers, where in 2008, it was 41%. In 1970, over 50% of unwed mothers were under the age of twenty, in 2008, it was only 22%. If you remember, above the graph I said that shotgun marriages dropped and unmarried births rose. To me, it would seem logical to assume that the rise in unmarried mothers is because of the drop in shotgun weddings. And if this is the case, then the 41% of women getting pregnant today would have been pregnant back in the 18th century as well. This means that the elders that calls our generation’s women “sluts” really should just call them “independent”, because that seems to be all that has changed. While it may take women today longer to get pregnant because of “the pill”, allowing them to have more than one sexual partner, the generations of past did not have the same option. It was a “one and done” kind of deal. Fertility rates are the same today that they were one-hundred years ago, so this cannot be a factor either. “The pill” did not become public to unmarried women until Eisenstadt v. Baird, in 1972. So for me to tell you that before the 1970’s, that the average marriage age was lower and after the 1970’s, the average marriage age rose, this should come to no shock. The adding of years to the average was just the effect of “the pill”, not a change in morals.
There is an interesting debate that I ran across. It is of the “which came first, the chicken or the egg” variety. There is an interesting theory that birth control and abortions killed shotgun weddings or possibly that it was the other way around, that the shotgun weddings’ death sparked the nation’s interest in birth control and abortions.  Either way, the two are definitely connected. Here is one explanation on the decline of shotgun marriages: 
What links liberalized contraception and abortion with the declining shotgun marriage rate? Before 1970, the stigma of unwed motherhood was so great that few women were willing to bear children outside of marriage. The only circumstance that would cause women to engage in sexual activity was a promise of marriage in the event of pregnancy. Men were willing to make (and keep) that promise for they knew that in leaving one woman they would be unlikely to find another who would not make the same demand. Even women who would be willing to bear children out-of-wedlock could demand a promise of marriage in the event of pregnancy.
The increased availability of contraception and abortion made shotgun weddings a thing of the past. Women who were willing to get an abortion or who reliably used contraception no longer found it necessary to condition sexual relations on a promise of marriage in the event of pregnancy. But women who wanted children, who did not want an abortion for moral or religious reasons, or who were unreliable in their use of contraception found themselves pressured to participate in premarital sexual relations without being able to exact a promise of marriage in case of pregnancy. These women feared, correctly, that if they refused sexual relations, they would risk losing their partners. Sexual activity without commitment was increasingly expected in premarital relationships.
As this post has gotten rather wordy, I will end it here.
If I were a member of MythBusters, I would stamp the myth of morality as busted. The facts are clear. Clearly, the Virgin Mary was not the only person before the sexual revolution of the 60’s to show up to the altar bearing child. Starting from colonial days where some towns had 40% of their brides pregnant at the altar, to 2008 where 41% of children are born of unmarried women, (40% / 41% –hmmmmmmm) the myth of abstinence has been busted!
I had been asked to focus on the sexual revolution from the 60’s and honestly I was overwhelmed enough with this topic to try to tie in any further angles. However, I will doing an exclusive piece specifically on the sexual revolution. Stick around because you should see that next!
 Jackson-Amautu, Natasha. eHow:History of Dating & Courtship