Hair loss is more than a possibility for most men in their 30s and beyond. As soon as thefirst signs of hair loss emerge, the questions shift from “if and when” to “how much, how quickly, and what next?”
Part of navigating the hair loss experience is setting expectations and knowing what’s to come, or at least having a predictive pattern to help guide your plan of attack. That’s why researchers have worked for more than a century to develop various measurement scales for pattern balding, both in men and women alike, drawing from massive and diverse data sets.
These common “stages of a receding hairline” are far from perfect. Outliers and anomalies are par for the course with any broad-swath scientific analysis. But what we can learn from these classification systems is invaluable and can alter the course of hair restoration for millions worldwide.
Let’s explore the stages of a receding hairline acrossvarious classification frameworksand create a practical, action-oriented approach to hair loss for the next generation of patients and doctors.
How Is Male Hair Loss Measured?
Men are far more likely to experience a receding hairline earlier in life and to a greater degree than women. Therefore, most scientific efforts to classify hair loss patterns have focused on male pattern balding (genetically-induced androgenetic alopecia).
Measurement scales have taken various forms throughout the history of modern medicine. What we have now, however, is a fairly reliableset of evaluation methodsand classification systems to help men assess and predict hair loss.
Here’s a closer look at the most prevalent types of male hair loss pattern classes, their meaning, and their practical usage.
Hamilton
First developed by an anatomist in the early 1950s, the Hamilton scale emerged among a series of breakthroughs in hair restoration science and tech. The original study was based on a sample of more than 300 men exhibiting hair thinning to different degrees on the scalp’s front hairline and rear vertex.
Hamilton’s initial sketches may appear crude through a modern lens, but his findings should be familiar to all.
Including eight distinct types, Hamilton outlined the typical progression of pattern balding, starting with the definitive formation of a widow’s peak through symmetrically receding hair on either side of the scalp.
From there, a more pronounced M-shaped hair pattern becomes visible in stage three, concurrent with noticeable thinning on the crown, typifying early “bald spot” development.
Consequently, stages five and six see the expansion of the bald spot as the remaining hair of the widow’s peak recedes completely.
In the final stages of pattern balding, Hamilton observed the meeting of the receding hairline with the expanded bald spot at the top of the crown. The next stages show the continued loss of hair from the center of the crown across either side until nothing remains but the horseshoe-shaped hair on the sides of the head and rear.
Norwood
Building on Hamilton’s research more than two decades later, the dermatologist and hair transplant surgeon O’Tar Norwood broadened his study to more than 1,000 males. The differences in Norwood’s classification system are slight but offer greater detail and a few alternative balding patterns for reference.
For example, Norwood delineated between two versions of “type 2” balding, one featuring a deep and wide M-shape pattern and the other with a more shallow curve and shorter widow’s peak.
Norwood’s scale is now the definitive classification system for male pattern balding. However, some practitioners combine his chart with Hamilton’s and refer to them in tandem as the Hamilton-Norwood Scale.
Alternatives
While the Hamilton-Norwood Scale remains the go-to system for dermatologists, surgeons, and everyday doctors, several alternative frameworks have emerged in the past half-century to provide more detail and context to the hair loss field.
Some scales aimed to summarize hair loss patterns in a more concise chart, with mixed results. Bouhanna, for example, presented an abbreviated classification system in 1976, which featured six distinct hair loss types. This system highlighted the major stages of hair loss while omitting certain incremental progressions.
Blanchard, in 1984, introduced six-stage measurements to the mix, giving doctors a more objective means to analyze hair loss in men. However, the system didn’t go mainstream, as the measurements were difficult to scale and didn’t provide actionable information in most cases.
Most recently, Korean researcher Koo published a simplified classification system with six subtypes arranged by English alphabetical letters for quick determination. Koo’s system is concise and commonly used to diagnose patients and plan surgeries.
Women’s Hair Loss Scales
Women may not experience hair loss at the same rate as men, but patterns develop somewhat differently when they do. Here are the two mainstream classification systems for female hair loss and what women can expect according to either approach.
Ludwig
In the Ludwig study, nearly 500 females were observed across different stages of hair loss. The research concluded with the consequential discovery that most women’s hair loss occurs along the central “part” of the hair, distinct from male pattern balding observed in the Norwood-Hamilton framework.
In other words, women should look beyond the hairline and focus primarily on the quality and density of hair in the center of the head.
While these observations are more difficult to make in the mirror, Ludwig’s revelations helped female hair loss patients make quicker, more accurate diagnoses with better results.
Savin
In 1992, Savin expanded on Ludwig’s simple chart with nine computer-generated images. These showcased three progression types for female pattern baldness, again emphasizing the central crown as the primary zone for miniaturization, thinning, and depletion.
Theadvantages of Savin’s modelinclude acknowledging vertical pattern thinning as an issue rather than spreading hair loss across the horizontal plane of the scalp. This encouraged women and doctors to assess new hair loss dimensions and more aggressively diagnose trends.
Savin also revealed that women could also experience the deterioration of the frontal fringe, especially once hair on the crown has thinned significantly. As a result, women today are made aware of hair loss in all its forms, especially at early stages, thanks to Savin’s findings.
