Honest question, and no research on topic that I could quickly find, despite there being a cottage industry for academic articles about what correlates with an hourglass vs. a tubular waist-to-hip ratio.
I've been looking into the history of the pro-life movement, and since there's an apparent revival under Millennial college students, I checked out Google Images for "pro-life students" to see what they're like -- normal, hipster, etc.
While it wasn't every girl, they were far more likely to have hourglass shapes, in an age where it seems like you don't see that body type much anymore, especially among Millennials. Even when they were a bit overweight, they still had hourglass shapes, rather than being uniformly wide blobs. They also smile more. More designed for birthing in their physiology, more pro-natal in their political views.
Some examples (girl on left, girl in peach shirt, girl in orange shirt):
The pro-choice students had more boyish waist-to-hip ratios, and generally didn't smile (notwithstanding one of the examples below). When they were fat, they were fat all over, not in a Rubenesque way. Bodies less capable of conceiving and delivering, minds less inclined to protect childbearing.
See for example: