It's no longer practical, in a two job household, to avoid splitting responsibilities when caring for a newborn. Dividing up care responsibilities doesn't have to be a difficult process or something that drives you and your wife apart.
Traditional gender roles often have to be ignored when caring for a newborn. A husband may have to wake up in the middle of the night, and bottle feed a newborn. Don't use breast feeding as an excuse: bottles of breast milk should be chilled in the fridge to give mom a break from night feeding duties.
Break down both your daily schedules, and carefully craft a care plan around the demands of work. Remember that your baby always comes first. A newborn won't follow your strict schedule, but a basic daily plan can help avoid confusion between you and your husband.
Stick to this plan whenever possible. If you said you'd pick up diapers after work, do it. Don't avoid responsibility because you're tired. Avoiding responsibilities can lead to strain on the other parent, a situation that can lead to marital problems.
This is why giving the other parent a break is so important. If your wife feels she is the only one taking care of your child, then she will begin to resent you and, potentially, the child.
For example, a newborn may suddenly start crying while one of you is taking a break. The parent not resting should care for the child, and let the other parent continue to relax.
A newborn has the potential to add a new element of strain to a marriage, but if you and your significant other communicate properly, create a plan, divide responsibilities properly and help support each other, it should become a learning and growing experience that will bring you closer together.