Stress from adjusting to a newborn baby in the family can affect your health both mentally and physically. Lack of sleep is the primary factor. Lack of sleep can result in depression, anxiety, obesity which can lead to diabetes, high blood pressure, high cholesterol and a number of other medical problems.
It's super important to continue to take care of yourself, to take time from yourself while you're using all of this extra time to care for this new human in your life.
Mental health is another thing to consider when having a newborn. Having a new baby in the house, another mouth to feed, another life to care for can be a stressful experience. Often times a parent might not be willing to share their feelings and any depressed mood and any anxiety, which can get balled up and magnified and become a problem later on. It's really important to stay open with your partner and to address any of those mental health issues before they can become a problem.