Being over 35 is considered a 'risk' factor in our maternity notes in the UK. It can make the difference between being under consultant care or not (usually in addition to at least 2 other factors). Have been told by my midwife and GP in both pregnancies that they personally dont consider it a risk factor as it is so common for women to start their families at 35+ these days... This is my second pregnancy over 35 and my age has never been an issue...
I've been told my a friend who is a medical student that 35 is based on the graph of risk factors to age; at 35 the line begins to incline at a slightly sharper rate; there's a more dramatic rise at 40. But to say that statistically pregnancies at 35 are slightly riskier than at 34 is not to say that every 35+ mom is high risk, and most doctors and midwives will judge based on the individual. I'm still classed as low risk at 35, and my nuchal screening test came back with my risk factors equivalent of a 20 year old.