Apparently 0.8% of American mothers report that they became pregnant as virgins.
The likelihood that some of these mothers had in fact had classical penile-vaginal intercourse, but didn't wish to report it, is indicated by the fact that these self-proclaimed virgin mothers were twice as likely to have taken an abstinence pledge than were other mothers.
But others of these virgin mothers were likely telling the technical truth: that they had not yet engaged in penetrative intercourse when they became pregnant. Sperm, you see, swim, and if they are deposited on the exterior of a person's body, they can make their way inward all by themselves. Thus, pregnancies regularly result from "outercourse."
As an intersex person, I think about this a lot, because doctors often claim that genital surgery is not cosmetic but functional, as without an "adequate" vagina or "repaired" penis, we will be infertile. To which my sophisticated academic rebuttal is: nuh uh! You need the right hormonal balance to go with the gametes, and some way in or out, but it certainly doesn't need to be a vagina that can "accept" a penis, or a phallus that is large and has the urethral opening at the tip.