hiya, like fryc says, 12 weeks is the safe point. dont stress about it, or let your wife stress about it as its no good for baby. mum needs to chill out, eat well and relax.
they do say that age and history is a factor, but there are LOADS of older ladies who have perfectly healthy babies, and my friend has 2 beautiful healthy girls after surviving cancer so the human body is a fantastic thing.
if you are genuinly over-worried, speak to your midwife and she can give you the statistics, but generally theyll only make you worry more.
well done and congratulations, enjoy this time, even tho your wife may get stressed and upset for no reason at times, as the hard work begins once your bundle of joy arrives!!
oh, i let it slip by accident at 8 weeks to a friend, but we waited til 12 wks to tell friends and family just in case