I'm currently on a Victorian era fiction binge, and it seems like every book has women fainting left and right, perfectly healthy people dying from getting rained on, being overwhelmed to death from emotion, and other seemingly ridiculous maladies.
Did people during this time period really have such weak constitutions? If so, was it just from harsh their living conditions? Or, since most novels tend to portray upper class characters, was their poor health related to all of the basically inbreeding going on between well-off English families? Or is it all just a literary trope from the time?
I cannot speak to the actual, physical health of Victorians, but I did once write an answer on the related subject of why one shouldn't take representations of fainting in period fiction as just a reflection of what people were actually doing:
Part of the answer to your question is that it really was quite easy to fall ill and die in the Victorian period, certainly in the earlier part of the nineteenth century, before the development of germ theory and well before the arrival of antibiotics. But of course this applied to every previous period – and yet we do seem to hear more about the weakness of women in Victoria's time than we did before.
The explanation for this lies in the medical theories of the age, which viewed women's bodies as especially problematic. I wrote about this in an essay about Philippa Fawcett, who astounded her contemporaries and gave many people pause for thought by becoming the first woman to take first place in the Cambridge mathematics tripos - then widely viewed as the most demanding intellectual test that could be sat anywhere in the world. The whole essay is, I hope, worth reading (and it has a nice punch-the-air conclusion), but the portion that helps to explain your observation is this one:
To be a woman in the Victorian age was to be weak: the connection was that definite. To be female was also to be fragile, dependent, prone to nerves and—not least—possessed of a mind that was several degrees inferior to a man’s. For much of the 19th century, women were not expected to shine either academically or athletically, and those who attempted to do so were cautioned that they were taking an appalling risk. Mainstream medicine was clear on this point: to dream of studying at the university level was to chance madness or sterility, if not both...
Today, the science that underpinned those views seems crackpot. To the Victorians, it was breakthrough stuff. Central to the 19th-century concept of human development was the idea that the adolescent body was a closed system; there was only so much energy available, and so a body in which resources were diverted to mental development was one in which physical development necessarily suffered. This was thought to be a particular problem for women, because their reproductive system was far more complicated than men’s and so consumed a greater proportion of the body’s resources. A young woman who studied hard during puberty was believed to be taking special risks since “the brain and ovary could not develop at the same time,” as historian Judith Walzer Leavitt points out.
The same problem very much applied to illness; women were considered to be more prone to disease than men because their bodies devoted a higher proportion of their limited energies to the demands of motherhood.