If the woman over 40 is just only to carry on the child there could be no risk for birth defects as it's not her eggs. Her eggs would be the ones at risk. If she still early 40's even her own eggs are most likely to be fine (the risk for birth defects is always small). She should be in good health thought for a healthy pregnancy. So if that's what you want to do and you can afford this kind of procedure the go for it.