My father would have died of severe illness in his teens so I would not have been born to die of several possibilities - first up would have been severe pneumonia when I was two.
I was hospitalised young with an infection that left me dehydrated. They fed me antibiotics, so possibly that would have done me in.
More recently, modern psychiatry is a life-saver.
That's easy. Appendicitis, age 8.
Still on Life #1 here - while I've had a few close calls and plenty of stories of almost dying, I haven't yet had one where medical services were the ones that saved the day. Thankfully. Hopefully it stays that way for a while longer yet.
Of course I'd also be the only one in my family who was still alive, so it would be a pretty lonely life #1...
I too believe that I'd still be alive! Surely more of us than is implied would actually have survived.
Some of these things possibly would cause health problems that linger entire lives but do not necessarily imply certain early death, and I suspect that our standard of what problems are acceptable to just live with have changed just as much as our ability to treat them has.
Bleeding at miscarriage, childbirth, and fibroids
Bad teeth - and they're not even that bad
None of these might have killed me but they sure would have made life miserable. But add malnutrition and they all might have been fatal.
I wouldn't be dead (I hope), but a tumor that in this timeline was removed from beneath my collarbone when I was 29 would have (if left to do its thing) ultimately rendered my right arm useless.
Also, I would have never been born, as my mother had both Appendicitis and an ectopic pregnancy before I got here.
But for vaccination, I might possibly have gotten tetanus a couple of times - and, for that matter, any number of other infectious diseases for which vaccines are now common. But that's not confirmed. As far as confirmed woulda-died-but-for-X cases, I'm probably still on life #1.
My daughter though - without bottled oxygen she very likely wouldn't have lived beyond her first day (I at first wrote that without CPAP and suction she would have died, but in fact the need for those things might have been iatrogenic - the bad bleeding in her lungs didn't start until she was intubated, and I caught a few comments suggesting the intubation might not have been done correctly).
I'd have died in horrible agony when my appendix went, when I was twelve. If that didn't happen, tonsillitis that choked off my breathing at twenty, or a dental abcess at twenty-two; pneumonia at twenty-four, or at twenty-eight. Of my mother's other children--one would have died of complications of asthma, scores of times before adolescence; she spent weeks of time in an oxygen bubble. One would have died of strep, when it went systematic. One might have died of infection after a bicycle accident that tore his knee open to the bone; one might have lost a foot when she dropped a fishing net ball on it as a young child. Of the six of us kids, one brother and one sister might have survived.
Of course, my mother would never have made it to adulthood, either...
I had a very bad illness when I was just a couple months old. I don't know what it was, but I was hospitalized, so very well could have died. Other than that, I've been pretty lucky, with mostly minor injuries. Of course, before the germ theory, who knows if any of those would have gotten infected and killed me.
Interesting to think about, though. Glad I live now.
Pneumonia at the age of 4, possibly- but given that the doctor* didn't notice it for several weeks and kept telling my parents it was viral and to wait for it to clear up on its own, I might have survived it even without the treatment I eventually got. On the other hand, one of the chest infections I've had since then because of the lung damage from it probably would have killed me without antibiotics.
What's more likely is that I would have died of something I'm vaccinated against. Or, given where my family were at the time, been massacred by either Turks or Cossacks.
*I have nothing but admiration for the modern medical profession as a whole, but that doctor in particular was an idiot.
Appendicitis at 8 almost did kill me, and likely would have even 20 years earlier. A few serious infections resulting from various accidents - I once spent 2 weeks in hospital on a high powered antibiotic IV drip to save my leg and life after a skiing accident got infected.
I'd certainly have horrible tooth pain, a hernia, horrific heartburn. My wrist would barely work, ditto my ankle. Most of my friends would be dead, my wife would have died before meeting me.
Who knows what diseases I haven't caught as a result of vaccination?
Tragic story of medical advance: My aunt developed a significant 'benign' tumour in her brain as a teenager. The procedure at the time was very invasive - she flew to Scotland to have it done. Tumour cured but an infection from the surgery killed her. No more than a few weeks later a new, noninvasive procedure became available - it would not have killed her.
I would have died in the womb. All three of my mother's children (including me, obviously) had compressed umbilical cords - her first child died during labour.
i'm another pnuemonia victim. i got it twice as a toddler. my brother would still be alive though, just deaf in one ear from a benign tumor.
I would have died when giving birth to my children at 38 (lost a lot of blood, had a transfusion), except I wouldn't have gotten pregnant in the first place as we needed medical help (ICSI) for that too. But then, without contraception, maybe I would have gotten pregnant by my first boyfriend.
And I certainly would have died last year at 44, of meningitis. I was on an antibiotics drip for weeks.
And then some things that might or might not have been fatal - measles at 6, a rusty nail in my foot at 28.
ObFiction - Kate Atkinson, Life After Life, where at the start a woman dies at birth, and again and again and again at greater ages.
To the best of my knowledge, I'm still on life #1 (of course, as with just about every modern human, this is dependent on what childhood vaccinated diseases may or may not have gotten me). The only major medical issue I've ever had was a broken collarbone at age 8 or 9, and the medical treatment for that was pretty minimal.
I'd likely still be here. No really serious illnesses in my life, no hospital admission, not even broken bones or stitches. Same for both my parents. Of course, it's always possible that I would have contracted some 19th century pestilence if I had been alive back then.