It is generally normal for babies to pass less urine at night compared to during the day. As long as your baby is passing a sufficient amount of urine throughout the day and does not show any signs of discomfort or dehydration, there is usually no cause for concern. However, if you notice any significant changes in your baby's urinary habits, such as a sudden decrease in urine output or signs of distress, it is important to consult with a healthcare professional for further evaluation.