The Relationship Between Finger Ratio and Development in Infants

NCT07525726 | Enrolling By Invitation

• 1 other identifier: Digit ratio and development
• Study Type: observational
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

One of the most prominent indicators of prenatal androgen exposure is considered to be the ratio of second and fourth finger lengths (2D:4D). The 2D:4D finger ratio refers to the ratio of the length of the second finger (2D; index finger) and the fourth finger (4D; ring finger). Evidence suggests that 2D:4D is developmentally stable and stabilizes from the second trimester of pregnancy. It has been reported that the 2D:4D ratio correlates positively with estrogen and negatively with testosterone. In both sexes, prenatal testosterone levels are inversely related by a 2D:4D ratio, which does not change with age. Androgens can have direct trophic effects on target cells or indirectly affect neuronal growth through neurotrophic mediators released locally by steroid-sensitive neuronal or glial cells. Prenatal testosterone can have long-term organizational effects on the structure and function of various body systems (e.g., cardiovascular and musculoskeletal systems) that are important for physical activity and exercise.

Conditions

Infant Developmental Assessment

Keywords

motor development; sensory processing; 2D:4D ratio; digit ratio; infant; Prenatal androgen

Outcome Measures

Primary Outcomes (3)

• Sensory processing

  The Test of Sensory Functions in Infants is a standardized assessment tool designed to evaluate sensory processing abilities in infants aged 4 to 18 months. The TSFI examines responses across multiple sensory domains, including tactile, vestibular, visual, and oral-motor functions, providing a comprehensive profile of an infant's sensory processing. In the tactile deep pressure response section, it is scored as 0: reverse response, 1: mild defensive response, and 2: integrated response. In the adaptive motor response section, it is scored as 0: no response, 1: disorganized, 2: partial, 3: organized. In the visual-tactile integration section, it is scored as 0: hyperactive, 1: hyporeactive, and 2: normal. The oculomotor test section is scored as 0: no response or poorly integrated, 1: well integrated. Response to vestibular stimulation is scored as 0: adverse response, 1: mild defensive response, and 2: integrated response. The total score ranges from 0 to 49.

  12-18 months

• Motor development

  The Peabody Developmental Motor Scales, Second Edition, is a standardized tool used to assess gross and fine motor skills in children from birth to 5 years of age. The assessment comprises six subtests: reflexes, stationary, locomotion, object manipulation, grasping, and visual-motor integration, which together provide a comprehensive evaluation of a child's motor development. It has been widely validated in both typically developing children and those with various developmental disorders, making it a reliable and widely used instrument in pediatric motor assessment. Items are scored with 0, 1, and 2 points. When the child performs the item according to the specified item criteria, 2 points are given. One point is awarded when the behavior occurs, but the criteria for successful performance are not fully met. A score of 0 is given when the child is unable to try the item or does not reveal any skills when he tries it. Results are expressed as raw, standard, or total motor scores.

  12-18 months

• Digit Ratio

  The lengths of the second (2D) and fourth (4D) fingers of the participants will be measured separately on each hand. Measurements will be taken with the participants' hands placed flat on a surface with the palms facing upwards. Measurements will be performed using a digital caliper with a precision of 0.01 mm, 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 on both hands. To increase the reliability of the measurements, the assessments will be performed twice by a researcher who is blind to motor development and sensory processing skills.

  12-18 months

Study Arms (1)

Healthy infants

Healthy, full-term (37-40 weeks of gestation) infants aged 12 to 18 months and their families will be invited to participate in the study.

Behavioral: Digit Ratio; Behavioral: Motor development; Behavioral: Sensory processing functions

Interventions

Digit Ratio BEHAVIORAL

The lengths of the second (2D) and fourth (4D) fingers will be measured separately on each hand. Measurements will be taken with the baby's hands placed flat on a surface with palms facing upwards. Finger length will be defined as the distance from the midpoint of the proximal crease at the base of the finger to the distal end of the finger. A digital caliper with a precision of 0.01 mm will be used, and two separate measurements will be taken for each finger, with the average value recorded. Based on these measurements, the 2D:4D finger ratio for each hand will be calculated by dividing the length of the second finger by the length of the fourth finger.

Healthy infants

Motor development BEHAVIORAL

The Peabody Developmental Motor Scale-2 (PDMS-2) is planned to be used to assess motor development. The PDMS-2 test is designed to identify developmental delays in children aged 0-72 months. It is used to evaluate children's motor development with separate tests and rating scales for both gross and fine motor skills.

Healthy infants

Sensory processing functions BEHAVIORAL

The Test of Sensory Functions in Infants was planned for use to assess babies' sensory development. The TSFI is frequently used to evaluate the sensory processing functions of infants aged 4-18 months. It is used to determine whether and to what extent a baby has a sensory processing problem. It consists of 24 items. The TSFI requires the baby to be stimulated and interact with various materials. The total score ranges from 0-49, and the test has normative values for different age groups. Although it can be used from the fourth month onwards, the most reliable and valid results are obtained between 7-18 months.

Healthy infants

Eligibility Criteria

• Age: 12 Months - 18 Months
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17)
• Sampling Method: Non-Probability Sample

Study Population

The study will include healthy, full-term (37-40 weeks of gestation) infants aged 12 to 18 months.

You may qualify if:

• Term infants (37-40 weeks),
• Infants aged 12-18 months

You may not qualify if:

• Preterm infants,
• Infants with congenital infections or proven genetic changes,
• Infants and mothers diagnosed with metabolic, neurological, and genetic diseases,
• Maternal diabetes,
• Intrauterine growth retardation,
• Infants with a history of hand-related surgery,
• Children whose parents did not volunteer to study

Sponsors & Collaborators

• Nigde Omer Halisdemir University: lead

Study Sites (1)

Nigde Omer Halisdemir University

Niğde, Turkey (Türkiye)

Location

Related Publications (3)

• Cay M, Gurel S. The relationship between mothers' second and fourth finger lengths (2D:4D) and anthropometric measurements (height, weight, head circumference, and 2D:4D) of the newborns. Am J Hum Biol. 2022 May;34(5):e23700. doi: 10.1002/ajhb.23700. Epub 2021 Nov 9.

  PMID: 34751980 BACKGROUND

• Ernsten L, Korner LM, Heil M, Schaal NK. The association between 2D:4D digit ratio and sex-typed play in children with and without siblings. Sci Rep. 2024 Jul 2;14(1):15231. doi: 10.1038/s41598-024-65739-1.

  PMID: 38956189 BACKGROUND

• Paukner A. Digit ratio (2D:4D) and its behavioral correlates in infant rhesus macaques (Macaca mulatta). Dev Psychobiol. 2020 Nov;62(7):992-998. doi: 10.1002/dev.21917. Epub 2019 Sep 12.

  PMID: 31512755 BACKGROUND

MeSH Terms

Interventions

Digit Ratios

Intervention Hierarchy (Ancestors)

Anthropometry; Physical Examination; Diagnostic Techniques and Procedures; Diagnosis; Body Weights and Measures; Investigative Techniques; Biometry; Epidemiologic Measurements; Public Health; Environment and Public Health

Study Officials

• Rabia ZORLULAR

  Nigde Omer Halisdemir University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: CROSS SECTIONAL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal investigator

Study Record Dates

• First Submitted: April 6, 2026
• First Posted: April 13, 2026
• Study Start: April 6, 2026
• Primary Completion (Estimated): April 1, 2027
• Study Completion (Estimated): April 1, 2027
• Last Updated: April 15, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)