Delayed Menstruation in Girls: What You Need to Know As girls enter puberty, they often look forward to experiencing the physical and emotional changes that come with this stage. One of the most significant milestones is the onset of menstruation. However, for some girls, this milestone may be delayed. What is a normal age range for menstruation to start? Typically, girls start their periods between the ages of 11 and 14, with the average age being around 12-13 years. However, it's essential to