Female digit length ratio (2D:4D) and time-to-pregnancy

Area of Science:

• Reproductive Endocrinology
• Human Fecundity Research
• Prenatal Hormone Exposure

Background:

• The 2nd- to 4th-finger ratio (2D:4D) is theorized to reflect in utero androgen exposure.
• Altered fetal androgen exposure may impact adult female fecundity.
• Time-to-pregnancy (TTP) is a key metric for assessing fecundity in human populations.

Purpose of the Study:

• To investigate the association between the female 2D:4D ratio and fecundity.
• To determine if 2D:4D can serve as a predictor of time-to-pregnancy (TTP).

Main Methods:

• Analysis of data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study.
• Inclusion of 696 mothers with TTP and 2D:4D measurements collected during follow-up.
• Statistical analysis using discrete-time Cox proportional hazard models, adjusting for confounders.

Main Results:

• No statistically significant association was found between the female 2D:4D ratio (right or left hand) and TTP.
• Analysis by tertiles and dichotomous categorization of 2D:4D did not reveal significant differences in fecundability.
• The study possessed high statistical power to detect a potential association, strengthening the negative finding.

Conclusions:

• The study does not support a link between the female 2D:4D ratio and fecundity as measured by TTP.
• Further research is needed to clarify the role of 2D:4D as a marker of in utero androgen exposure and its potential association with fecundity.