Mongolian Spots: What Should Parents Know About These Birthmarks?

Birthmarks come in all shapes and sizes. While birthmarks are common, some are more pronounced than others. Some birthmarks fade over time, but many others don’t. Some of the most common of these birthmarks are Mongolian spots or Mongolian blue spots. Known in the Philippines as balat, old wives’ tales associate having these markings with bad luck. How do these birthmarks actually develop and do Mongolian spots go away?

What Are Mongolian Spots?

Mongolian spots are the most common type of birthmarks in infants. Doctors almost universally regard them to be benign. So if you find these birthmarks on your baby, there is absolutely nothing to be concerned about.

More often than not, the markings measure less than 5cm and come in irregular shapes. These marks also tend to be bluish green, blue-gray, or brown in color.

Contrary to their name, birthmarks are not always present at birth. Some develop weeks later. Most birthmarks are permanent but a few may fade as a child grows.

Research from 1981 noted that these birthmarks were most seen in the sacro-gluteal region, or behind the thighs and below the buttocks, of infants. The shoulders are the next most frequent place where they appear. These markings appear on babies regardless of race and culture.

Do Mongolian Spots Go Away?

In 1988, a study was published which studied these specific birthmarks in Chinese-Canadian children. Mongolian spots were present in all newborns and disappeared slowly. At six years, the rate of disappearance accelerated. By the time the children were 10 years old, the researchers found no more old or new markings.

The gluteal and lumbar areas (the buttocks and lower back) were other places to find these markings on the infants. Regardless of age, 58% of the boys and 53% of the girls had the birthmark.

Another study was conducted in 2010 to determine the frequency and presentation of Mongolian spots. This was also done to assess if these birthmarks evolved with age. The majority of the 2,313 babies studied had a single patch measuring less than 5cm. At six months, 11.5% showed the birthmarks fading away while 13.1% had the spots disappear. At one year, 14.2% showed fading while 42.3% showed complete disappearance.

Multiple patches, extrasacral position, a size larger than 10 cm, and dark-colored lesions were markers of persistence beyond one year for these birthmarks.

Mongolian Spots as Errors of Metabolism

While doctors view Mongolian spots as benign, they may be markers of something more. A study from 2005 reported that many appearances of this birthmark could indicate possible congenital errors of metabolism. The errors of metabolism included mucopolysaccharidosis and GM1 gangliosidosis. Further study is encouraged on these particular birthmarks. 

Key Takeaways

Mongolian blue spots are among the most common birthmarks in babies. They appear on babies regardless of race and culture, most often on the sacro-gluteal region, with shoulders being the next most frequent spot to find them. These usually appear less than 5cm in size and have irregular shapes.

There is no need to remove them because these birthmarks naturally fade away over time. Despite being the most common birthmark, these often do not last past one year on an infant. Larger or darker birthmarks may be more likely to persist, but even if they do, there’s no need for any worry. Mongolian blue spots are benign, and they have no harmful effects on your baby’s health.

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