Anecdotally I know of two shotgun weddings within my immediate work group of 10 people. Both are still married (one about twelve years later and one going on 20 years later, though she is separated and in the process of getting a divorce). Both are Catholic and were raised in an environment in which divorce was stigmatized (though the one who is still married seems to be happily so and is about to have her second kid).
Haven’t seen any stats, but they would be quite interesting if also broken down by age, religious background, etc.
BTW all birth control has a failure rate. Yes, even oral contraceptives.
What I don’t understand is the mindset that “contraception is a sin, so I won’t use it,” especially from people whose religious upbringing also dictates that premarital sex is a sin. If you’re going to do the latter, you might as well not bring a baby into the mix who had no say in the matter, but that’s probably a better GD topic.