Severity of Premenstrual Symptoms Predicted by Second to Fourth Digit Ratio

Abstract

Women of reproductive age often experience a variety of unpleasant symptoms prior to the onset of menstruation. While genetics may influence the variability of these symptoms and their severity among women, the exact causes remain unknown. We hypothesized that symptom variability originates from differences in the embryonic environment and thus development caused by variation in exposure to sex hormones. We measured the second to fourth digit ratios (2D:4D) in 402 young women and investigated the potential relationships of this ratio premenstrual symptoms using a generalized linear model. We found that two models (one with two predictors such as both hands’ digit ratios and the other with the difference between the two digit ratios, Dr-l) were significantly different from the constant model as assessed by chi-square test. The right digit ratio and Dr-l were negatively related to the symptom scores, and the left digit ratio was related to the scores. When premenstrual symptoms were classified into eight categories, five categories, including pain, concentration, autonomic reaction, negative affect, and control were associated with the digit ratios and Dr-l. Behavioral changes and water retention were not predicted by them. Arousal was predicted by Dr-l. The right 2D:4D is thought to be determined by the balance of testosterone and estrogen levels during early embryogenesis and is not affected by postpartum levels of sex hormones, while the left 2D:4D might be affected by the other prenatal environmental factors. We conclude that the embryonic environment, including the relative concentration of sex hormones an embryo is exposed to, is associated with the severity of premenstrual symptoms once menarche is reached.

Effects of gender, digit ratio, and menstrual cycle on intrinsic brain functional connectivity: A whole‐brain, voxel‐wise exploratory study using simultaneous local and global functional connectivity mapping

“…The effects of the menstrual cycle on the brain network properties might be different between the low and high digit ratio groups, because a permutation test more often revealed differences in brain regions (five regions) in the low digit ratio groups than in the high digit ratio group (three regions) for the global hubs and global nodes in a different manner (Figure ). The results may be related to the previous our study that showed women with a higher right 2D:4D ratio had lower premenstrual symptom severity (Kaneoke et al., ). Similar results were observed for the data with preprocessing 2 (Figure S9).…”

“…Third, according to our recent study, females with a lower digit ratio of the right hand tend to have greater premenstrual symptoms (Kaneoke et al., ). Thus, our low digit ratio group may have more participants with premenstrual syndrome and premenstrual dysphoric disorder than the high digit ratio group, which could affect the results (Comasco & Sundstrom‐Poromaa, ).…”

“…To measure each participant's digit length, we scanned an image of the right hand using a portable color scanner (CanoScan Lide 210, Canon Inc., Tokyo, Japan) with a spatial resolution of 4,800 × 4,800 dpi. The second (2D) and fourth digit (4D) lengths were measured from the proximal finger crease to the distal tip of the finger using a digital Vernier caliper to the nearest 0.01 mm, as described in a previous study (Kaneoke, Donishi, Iwahara, & Shimokawa, ; Manning, Scutt, Wilson, & Lewis‐Jones, ). In this study, we investigated the right‐hand digit ratio based on the previous studies; these studies showed that prenatal sex hormones affect the right‐hand digit ratio more than the left‐hand digit ratio (Honekopp & Watson, ; Manning et al., , ).…”

The association between second to fourth digit ratio, reproductive and general health among women: findings from an Israeli pregnancy cohort

“…McIntyre et al and Richards et al found a significant positive association between right 2D:4D and estradiol levels across menstrual cycle 28,29 , although Klimek et al found no such correlation 43 . In addition, Kaneoke et al found a negative association between right 2D:4D and severity of premenstrual symptoms 27 . These findings along with our finding regarding age at menarche support the association between 2D:4D and menses characteristics.…”

“…menarche [20][21][22][23] , puberty characteristics 24 , reproductive period 20 , age at menopause 25 , polycystic ovary syndrome 26 , severity of premenstrual symptoms 27 and estradiol levels across menstrual cycle 28,29 . Several studies found 2D:4D to be associated with reproductive cancers 25,30,31 .…”