I think the actual % risk of it happening again is only something your consultant can answer, but they themselves will have different opinions I bet. No-one knows what triggers labour to start with a full term baby or otherwise so determining the risk of another spontaneous labour is difficult to judge I think but obviously delivering due to other complications can be quantified more easily. Presumably if you had an infection, risk low next time, if you had a bash and an abruption risk low, if you have PE or IC the risk is huge but these things can be managed.
In my case, I was given a risk of 10-15% of another spontaneous labour as the research shows that cases where there is no obvious cause and the usual issues have been ruled out (IC, infection, abruption etc) you have good odds of going to term. I took these odds with a "glass half full" attitude and decided it was low and good enough to accept and was massively confident that I would go to term, or even past 30 weeks. I decided not to do any trials and I'm happy to discuss why but don't want anyone to feel I'm judging in anyway at all. I have allowed both my babies to do clinical trials so I'm not against trials and it will be interesting to see what the results of all the trials are.
My second labour felt to me like it started exactly the same as my first but was complicated by the baby disengaging when my waters broke and moving transversely, and I also had a massive placental abruption so ended up in theatre knocked out for an emergency cs. I'm interested to know what the consultant has to say about that - he may feel that the abruption was brewing before and triggered labour, but I don't think that was the case.
I can't have another baby as I've had incisions that mean I would most likely have uterine rupture if I went into labour again (don't much fancy that!) but if I could I might do a trial as I'm pretty much convinced myself I am unfortunately in that 10-15% that will just go into labour at 28 weeks or thereabouts - the trials really need people like us to have 3 or more babies to really test it out! So I will leave that up to you guys!! xx