When and How Fingerprints Form

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The nails on the fingers and toes start to grow, as does the baby's individualized fingerprints. The fingerprint patterns established by 19 weeks last for a lifetime. (Image Credit: Priests for Life)

Every person has unique fingerprints. Even people with an identical twin have unique fingerprints. These fingerprints start forming in week 12 when some cells in the middle layer of the skin, called the basal layer, start growing faster than the cells in the inner layer of dermis or outer layer of epidermis. The extra cells cause the skin to buckle and fold into ridges.¹ As the fingers grow, new ridges and branches form. Between 17 and 19 weeks gestation, a layer of keratin coats the surface of the skin. Smaller, secondary ridges form out of uneven keratin growth.

Any factor that can influence friction in the womb can influence a fetus’s fingerprint pattern. These factors include the density of the amniotic fluid, and the fetus’s size, location, and movement patterns.² The pattern of fingerprints established by 19 weeks remains consistent as the child grows. ³

Notice the fingernails starting to grow on the fingers of this fetus at 14 weeks. (Image Credit: Priests for Life)

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Sources

W. J. Babler, “Embryologic Development of Epidermal Ridges and Their Configurations,” Birth Defects Original Article Series 27, no. 2 (1991): 95–112.
Singh, RK, M Sharma, A Tarannum, W Pet-Paul, and L Bernard. “A Case of Three Deltas in a Fingerprint.” J Forensic Res 9, no. 413 (2018): 2. https://doi.org/10.4172/2157-7145.1000416.
Babler, W. J. “Embryologic Development of Epidermal Ridges and Their Configurations.” Birth Defects Original Article Series 27, no. 2 (1991): 95–112.

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All images and illustrations on The Voyage of Life were reviewed by credentialed scientists for accuracy.

Medical art animation was used to provide a schematic representation of fetal development, with some features, including timing, not to scale. The animation was chosen as an ethically uncompromised guide to fetal development. There are many real human images at each developmental age showing the most accurate fetal forms throughout development. A concerted effort was made to use images and material in which the human embryo or fetus did not undergo any known harm.

Page last updated on June 6, 2023

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When and How Fingerprints Form