Eyebrow hair loss can result from various factors, including:

Genetics: A family history of thinning or sparse eyebrows can influence your own eyebrow density and growth patterns.

Hormonal Imbalances: Hormonal changes, such as those occurring during pregnancy, menopause, or due to thyroid disorders, can affect eyebrow growth.

Medical Conditions: Conditions like alopecia areata, eczema, psoriasis, and certain infections can lead to eyebrow hair loss.

Over-Plucking or Waxing: Frequent and excessive plucking or waxing can damage hair follicles, leading to thinning or loss of eyebrow hair over time.

Trauma or Injury: Scarring or trauma to the eyebrow area from injuries, surgeries, or burns can disrupt hair growth.