Frequent urination can be quite common in young babies, especially around 4 months of age, because their bladder is very small and they mostly take liquid feeds throughout the day. Babies who are breastfeeding well or taking formula regularly may pass urine many times, sometimes even every few minutes. If the baby otherwise looks active, feeds normally, sleeps comfortably, and gains weight properly, frequent urination alone may not always mean a serious problem. Fever, unusual crying during urination, foul-smelling urine, vomiting, poor feeding, dehydration, or reduced weight gain may indicate a urinary infection or another issue. Very excessive urination with unusual thirst can also occasionally be linked to metabolic or kidney-related conditions, though this is less common. Continue normal feeding and monitor diaper output for a day or two. If the baby seems uncomfortable, develops a fever, or the urination suddenly becomes much more frequent than usual, consult a doctor.