Is It Safe To Conceive After The Age Of 35?

My son and his 34 year old girlfriend are serious and talking of having a baby after marriage. I have read several articles and some are refuting the evidence that the rate of abnormalities or miscarriage is much higher after age 35. They say that much of the negative research was done too long ago and it does not apply today. She is very healthy and does not smoke , drink or is overweight . What are your thoughts ?
Thanks Terry Holcomb