After birth , how do we ensure we are still spending enough time with each other ? How can I give enough time to my marriage and my child ?

I suggest not seeing both things as separate for most things -- having family time will be great for both wife and child. But obviously there are certain things that you don't wanna do if your child is around so those are the exceptions. When you want to spend time with your wife only, enlist the help of parents, in-laws and family to watch the child. And when your wife needs the occasional alone time (which she will), spend some time with the kids.

You can have family time in the beginning for the first few months. Or ensure that you have a rest day for a couple of hours with your husband.