To estimate the onset of menarche, which developmental milestone is most informative?

• A. The age of the mother's menarche
• B. The patient’s age at thelarche
• C. When adrenarche occurred
• D. Whether linear growth has stopped

Answer: (B)

The key idea is that the first visible sign of puberty in girls—breast development (thelarche)—best anchors the timing of when menarche will occur. Menarche usually follows thelarche by about two years, though there is wide individual variation. So knowing when breast development begins gives the most reliable estimate for the onset of menarche.

Relying on the mother’s age at menarche isn’t precise for predicting an individual daughter’s timing because familial patterns exist but are heavily influenced by genetic, nutritional, and environmental factors. Adrenarche marks adrenal maturation and the appearance of body hair, but this occurs somewhat independently of gonadal maturation timing and isn’t as predictive for when menarche will start. Stopping linear growth reflects the end of the pubertal growth spurt, which happens after menarche in many cases and varies widely, making it a poor predictor of when menarche will occur.