This is a tough one. I do know of doctors that will prescribe medication during pregnancy for depression when the risk of not doing so outweighs the risks of taking it. There are 'safer' choices. What is difficult about this is that she is stopping medication to get pregnant and is prone to it happening again. But I think if she talks to her doctor about it, they can best guide her. It will be important to monitor her during and after pregnancy. There are psychiatrists, by the way, that work specifically with women/hormonal related depression and mental health issues. That is their whole specialty and maybe a referral to this specialty within psychiatry would be of benefit to your wife. good luck
There are no medications to treat depression that are recommended as safe for a pregnant woman. Some are considered less problematic than others, but it is a risk both of birth defects and of the child being born with a brain having to withdraw from the medication. People do it. Most are told by their doctors to stop their medication until after breast feeding is over. The depression itself won't affect the birth, though nobody knows if depression might be genetic or not. Some women who have no depression at all are adversely affected by the hormonal fluctuations that come with being pregnant and having a child. But that can happen to anyone, it isn't specific to someone with depression. The bottom line is, women with depression have children every day. The most difficult part is the medication. Time to have a talk with your doctors.