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Enrolling by Invitation

NCT Number: NCT07627113

Prenatal Androgen and Skills

Due to the difficulties and risks of directly measuring prenatal hormone levels, biomarkers that indirectly reflect this exposure are used in research. In this context, the ratio of second to fourth finger length (2D:4D) is widely preferred because it is an easily applicable and non-invasive measurement. Evidence shows that 2D:4D stabilizes from the second trimester of pregnancy onward and exhibits strong sex differences across populations. The 2D:4D ratio is generally lower in men than in women. 2D is more strongly influenced by prenatal estrogen, while 4D is more strongly influenced by prenatal testosterone; this occurs during the first trimester of intrauterine fetal development. To our knowledge, studies examining the relationship between the 2D:4D ratio, an indirect indicator of prenatal androgen exposure, and dexterity and tactile discrimination are limited. Accordingly, the planned study aims to evaluate the relationship between the 2D:4D ratio and fine motor skills and tactile discrimination in healthy young adults.

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Key information

Conditions

Health Adults

Age range

18 year–40 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Nigde Omer Halisdemir University

Niğde, Merkez, Turkey (Türkiye)

About this study

Sex hormones experienced during prenatal exposure play a significant role in shaping certain lifelong characteristics by influencing both the physical and neurological development of individuals. The effects of these hormones, particularly on the developing nervous system, contribute to the emergence of behavioral and functional differences. Hand preference and certain behavioral traits in humans have been shown to be related to prenatal hormonal exposure. However, the development of these traits is not limited to hormonal influences alone, but is shaped by the interaction of genetic, environmental, and sociocultural factors. Due to the difficulties and risks of directly measuring prenatal hormone levels, biomarkers that indirectly reflect this exposure are used in research. In this context, the ratio of second to fourth finger length (2D:4D) is widely preferred because it is an easily applicable and non-invasive measurement. The 2D:4D ratio is generally lower in men than in women. 2D is more strongly influenced by prenatal estrogen, while 4D is more strongly influenced by prenatal testosterone; this occurs during the first trimester of intrauterine fetal development. However, whether the 2D:4D ratio is a reliable indicator of prenatal hormonal exposure is still a controversial issue in the literature. Therefore, examining the relationship between the 2D:4D ratio and various biological and functional characteristics remains important. To our knowledge, studies examining the relationship between the 2D:4D ratio, an indirect indicator of prenatal androgen exposure, and dexterity and tactile discrimination are limited. Accordingly, the planned study aims to evaluate the relationship between the 2D:4D ratio and fine motor skills and tactile discrimination in healthy young adults. It is hypothesized that prenatal hormonal exposure may indirectly shape finger morphology and receptor distribution by affecting skin and nervous system development, which may be a determining factor in tactile sensitivity and dexterity.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Healthy individuals aged 18-40
  • Having sufficient visual and auditory function to understand and administer the test,
  • Voluntary agreement to participate in the study and providing informed consent.

Exclusion criteria

  • Individuals with any musculoskeletal pathology,
  • History of upper extremity trauma,
  • Individuals diagnosed with metabolic, neurological, or genetic diseases,
  • Individuals with a history of hand surgery within the last 6 months,
  • Pregnancy or breastfeeding.

Treatment and study plan

Digit Ratio

Other

The second (2D) and fourth (4D) finger lengths of the participants will be measured separately in both hands by a physiotherapist with over thirteen years of clinical experience.

Fine motor skills

Behavioral

Hand dexterity will be assessed using the Purdue Pegboard Test. The test will be administered according to standard procedure with participants seated at a table. Participants will be asked to place the pegs into the corresponding holes as quickly and accurately as possible within a specified time (30 seconds).

Tactile Discrimination

Behavioral

To perform the 2-point discrimination tests, the Baseline® two-point discriminator will be used. Measurements will be applied to the distal phalangeal pulp of the index finger on both hands while participants are seated in a comfortable position with their eyes closed.

Primary outcomes

  1. 2-point discrimination test

    Time frame: 12 months

    To perform 2-point discrimination tests, the Baseline® two-point discriminator will be used. Measurements will be applied to the distal phalangeal pulp of the index finger on both hands while participants are seated in a comfortable position with their eyes closed. The test will begin at a distance of 8 mm, allowing participants to perceive the stimulus as two points, and then the distance will be gradually reduced. After 5 mm, measurements will continue at 1 mm intervals. In each application, both contact points will be applied to the skin simultaneously and with equal pressure, and participants will be asked to indicate whether the perceived stimulus is a single point or two points.

  2. Digit Ratio

    Time frame: 12 months

    Measurements will be taken after participants' hands are placed on a flat surface with palms facing upwards. Finger length is defined as the distance from the midpoint of the proximal crease line where the finger joins the palm to the distal point of the fingertip.

    Measurements will be performed using a digital caliper with 0.01 mm accuracy, two separate measurements will be taken for each finger, and the average value will be recorded. Based on the obtained measurements, the 2D:4D finger ratio will be calculated by dividing the 2D length by the 4D length in both hands .

  3. Fine motor skills

    Time frame: 12 months

    The test will be administered according to standard procedure while participants are seated at a table. Participants will be asked to place the pegs into the corresponding holes as quickly and accurately as possible within the specified time (30 seconds). In the dominant and non-dominant hand tests, participants will be asked to place pegs with one hand for 30 seconds, while in the both-hand test, the simultaneous use of both hands will be evaluated. The number of correctly placed pegs for each subtest will be recorded, and higher scores will be considered as better fine motor skill performance.

Sponsors and collaborators

Lead sponsor

Nigde Omer Halisdemir University

Other

Registry information

Official study title

Prenatal Androgen and Fine Motor Skills and Tactile Discrimination

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Jun 4, 2026
Registry last updated
Jun 4, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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