Age, maybe? Primary cause for fractures nowadays is osteoporosis, which AFAIK is more serious to women after menopause. Primary cause historically was accidents, with the opposite distribution.
For instance in Switzerland each year you have 550k non-professional accident (declared one to your employer) for 8.5M inhabitants. (Ref: SUVA annual report but only available in GE and FR)
Lifting weight helps bones get stronger, and Vitamin D is an essential nutrient in proper bone building.
100 years ago even, most people lived and worked on farms in the US (and many other places), now it's single digit percentages - and many of them spend it driving vehicles and similar less physical labor.
Seems an odd thing to mention/focus on. Any specific reason for including this?
At least as of 2007 those industries (and related industries) were 78% male [https://www.bls.gov/opub/mlr/2007/06/art2full.pdf]
There is also a similar visible skew in the power lifting, olympic lifting, or weight lifting communities for those into it recreationally.
It used to be we all spent more time lifting heavy things. However, post WW2 that has rapidly declined.
So one way to reduce or reverse this is if we ALL lifted heavy things more often. From a risk reduction perspective, that seems to be especially valuable for women?
Depends; women might be much more prone to injury from lifting heavy things.
* It's only the last couple of hundred years that a significant body of people doing work that does not have a large physical component - bone density is heavily influenced by stressing the bones regularly through exercise.
* It's only the last hundred years that childbirth-related mortality for women has plummeted. A lot of women would die in childbirth. Early industrial revolution era saw some parts of Europe have 20-25% of women die of childbirth. Now it's an extraordinary event.
* Following from that, menopause dramatically reduces bone density for women; one reason HRT was such a popular thing in the med-to-late 20th century was that it was seen as a panacea for removing the worst effects of menopause. Unfortunately it creates a lot of issues, as well.
* Diets change dramatically. Medieval people ate (generally) much less meat and sugar, but a lot of fresh (when in season) vegetables, some fruit, and a lot of grains. Early industrial food quality plummets as people move to urban areas without the ability to grow their own food. Rickets are a huge, widespread plague on urban poor (places like Glascow had rickets endemic well into the mid 20th century) for most of the modern era.
That's just wopk and diet. Consider that the averge medieval person walked everywhere, early moderns likewise, and only from the 19th century onwards did rail, cars, and so on see people getting about without considerable exercise being involved.