Prenatal Hormone Research Articles

Why Does Digit Ratio Research Fail to Give Any Implication Regarding the Organizational Effect of Prenatal Androgen?

Abstract. The digit ratio is a putative biomarker for evaluating the organizational effects of prenatal testosterone. This evaluation was performed by relating postnatal traits to digit ratio. We examined the relationship among digit ratio, depression, and positive/negative affect. A total of 335 university students who completed a set of questionnaires had both of their hands scanned, and the digit ratios were measured using a computer program. All the studied variables were insignificantly related to the right-hand digit ratio. The variables remained insignificant even when the data for males and females were analyzed separately. Furthermore, a meta-analysis, including a previous study combined with current data, showed no association between digit ratio and depression, although the current sample size of 355 could detect r = 0.2 at α = 0.05, and β = 0.2. The lack of association between digit ratio and depression was common, and the present results corroborated those of previous studies, which showed no association between digit ratio and depression. This nil result would be least likely attributable to an inadequate sample size, considering that the current sample size of 335 allowed the detection of r = 0.2 at α = 0.05 and β = 0.2, nor idiosyncratic results, given that the meta-analysis with previous relevant studies also concluded the same results. We extensively reviewed the relevant literature and evaluated the use of digit ratio as a biomarker for prenatal testosterone exposure in seven different perspectives. Nearly all the analysis showed the problems of using digit ratio as a biomarker for evaluating the organizational effect of prenatal hormones.

A single center retrospective study on hospitalization information for 812 cases of very low birth weight and extremely low birth weight infants

Objective To analyze the survival rate and hospitalization information for 812 cases of very low birth weight (VLBW) and extremely low birth weight (ELBW) infants. Methods The retrospective study was conducted in a single center, Department of Neonatology, Hubei Women and Children Hospital, from January 2009 to December 2014, where the data of 812 infants with birth weight(BW) less than 1 500 g was analyzed in regard to perinatal condition, treatment and complications of these in relation to prognosis. Results (1)A total of 621 cases(76.5%) had favorable prognosis.(2)There was a significant difference in the favorable prognosis rate between different BW groups (χ2=28.87, P<0.05) and different gestational age(GA) groups (χ2=14.77, P<0.05). The favorable prognosis rate for the male infants(χ2=4.69, P<0.05), puerpera age between 17-25 and 36-46 years old (χ2=11.19, P<0.05), usage of prenatal hormones(χ2=8.02, P<0.05), the infants without intrauterine infection (χ2=8.61, P<0.05), the mother without gestational hypertension (χ2=7.20, P<0.05) and gestational diabetes mellitus(χ2=19.2, P<0.05) were different compared to the control groups.(3)Infants with peripherally inserted central catheter (PICC) (χ2=33.31, P<0.05)and recovery birth weight within 10 days(χ2=29.65, P<0.05) had higher favorable prognosis rate compared to the control groups, which had significant differences.(4)Infants with intraventricular haemorrhage (IVH)(χ2=13.16, P<0.05), respiratory distress syndrome (RDS)(χ2=7.59, P<0.05), necrotizing enterocolitis (NEC)(χ2=13.02, P<0.05) and serious asphyxia (χ2=6.05, P<0.05)had lower favorable prognosis rates than those did not, with significant differences.(5)Logistic analysis: the lower BW, smaller GA, earlier birth, unused PICC, serious asphyxia, IVH, RDS were risk factors for poor prognosis(all P<0.05). Conclusions The favorable prognosis rate of VLBW and ELBW infants has improved gradually, and is closely related to GA, BW, maternal age, perinatal care, prevention complication, treatment of disease and social factors etc. Key words: Very low birth weight infant; Extremely low birth weight infant; Favorable prognosis rate; Treatment information; Single center study

Exploratory Analysis of the Links among Food Consumption Profiles, Prenatal Androgens, and Selected Measures of Quality of Life.

Prenatal sex steroids play a vital role in the development of the whole organism, and therefore also the brain. Exposure of the fetus to testosterone seems to be of special importance both for typical development and pathology. The key factor impacting offspring development (including prenatal androgen levels) appears to be diet, both in terms of shortage and excessive intake of certain food products. Prenatal steroid levels are measured using the ratio of the lengths of the second and fourth fingers (2D:4D). So far, the digit ratio (2D:4D) has been shown to correlate negatively with prenatal testosterone and positively with prenatal estrogen. Numerous correlational studies found relationships between the 2D:4D phenotype and differences in magnitude of many psychological traits. Certain social and demographic variables also correlate with the digit ratio. The present paper offers a preliminary analysis of correlations between diet, prenatal hormones’ levels (established based on the digit ratio), and selected social variables. One of the findings is that countries with high meat consumption present the so-called masculine digit ratio, while countries with plant-based diets – a feminine digit ratio.

Digit ratio (2D:4D) and handgrip strength in a Chinese population of Han ethnicity

BackgroundIn humans, the relative lengths of the index finger to the ring finger (2D:4D) is a sexually dimorphic trait which correlated with prenatal sex steroids and has been increasingly used as a promising tool to evaluate the impact of prenatal hormone exposure in some traits, such as physical performance. Handgrip strength (HGS) is one potent index of physical ability and its relationship with 2D:4D ratio has been discussed in several ethnic groups. AimsTo investigate whether there is a correlation between 2D:4D ratio and HGS in Chinese college students of Ningxia Han ethnicity. Methods608 students (211 males and 397 females) of Han ethnicity were recruited from Ningxia medical university. Photocopies and HGS of both hands were collected at Yinchuan city, in the Ningxia province of China. ResultsSexual dimorphism of 2D:4D and HGS were found, males had significantly lower 2D:4D and greater HGS than females. 2D:4D in both hands were significantly negative correlated with HGS in females and not in males. Conclusions2D:4D ratio is negative correlated with HGS in a Chinese population of Ningxia Han ethnicity and this association should be considered on the anthropological research within an evolutionary concept in the future.

Prospective and dyadic associations between expectant parents' prenatal hormone changes and postpartum parenting outcomes.

During the transition to parenthood, both men and women experience hormone changes that are thought to promote parental care. Yet very few studies have explicitly tested the hypothesis that prenatal hormone changes are associated with postpartum parenting behavior. In a longitudinal study of 27 first-time expectant couples, we assessed whether prenatal hormone changes were moderated by self- and partner-reported parenting outcomes at 3 months postpartum. Expectant fathers showed prenatal declines in testosterone and estradiol, and larger declines in these hormones were associated with greater contributions to household and infant care tasks postpartum. Women whose partners showed larger testosterone declines also reported receiving more support and more help with household tasks. Expectant mothers showed prenatal increases in testosterone and estradiol, and larger increases in these hormones were associated with lower partner-rated support. Together, our findings provide some of the first evidence that prenatal hormone changes may indeed be functional and that the implications of these changes may be detectable by co-parents.

Decreased digit ratio (2D:4D) and gastric cancer in Chinese men

BackgroundThe development of finger length is influenced by the level of hormones during pregnancy in the womb. The relative length of 2nd to 4th digit (2D:4D) is considered as a putative marker for prenatal hormone exposure and may represent an individual susceptibility to certain diseases, particularly those hormone-related cancers (e.g., gastric cancer). AimsThe aim of this study is to investigate whether there is a possible relationship between 2D:4D ratio and gastric cancer (GCA) in Chinese men. Methods94 male patients with GCA and 91 controls were chosen to participate in this study. Photographs of both hands were collected and then the lengths of second and fourth digits of both hands were measured. Left hand, right hand, mean hand, and right minus left hand (∆R-L) 2D:4D ratios were analyzed and compared. ResultsIn GCA group, 2D:4D ratios were significantly lower (right hand: p<0.01; left hand, mean hand: p<0.001) than controls. No association was observed between 2D:4D ratio and tumor staging (neither in tumor size (T) nor in lymph node involvement (N) or distant metastases (M)). There was also no correlation between 2D:4D ratio and age of onset. ConclusionsDecreased 2D:4D ratio may be an indicator for forecasting the susceptibility to develop GCA.

Prenatal and postnatal phthalate exposure and sex hormone changes in a 12-year follow-up birth cohort study

Introduction: Phthalate diesters are well-known environmental endocrine disruptors. However, few studies have examined their effects on children’s sex hormones using a birth cohort follow-up approa...

Genetic and Environmental Influences on Traits of Gender Identity Disorder: A Study of Japanese Twins Across Developmental Stages.

The present study examined: (1) gender and age differences of mean gender identity disorder (GID) trait scores in Japanese twins; (2) the validity of the prenatal hormone transfer theory, which predicts that, in dizygotic (DZ) twin pairs, twins with an opposite-gender co-twin more frequently exhibit GID traits than twins with a same-gender co-twin; and (3) the magnitude of genetic and environmental influences on GID traits as a function of age and gender. Data from 1450 male twin pairs, 1882 female twin pairs, and 1022 DZ male-female pairs ranging from 3 to 26years of age were analyzed. To quantify individual variances in GID traits, each participant completed four questionnaire items based on criteria for GID from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). Our most important findings were: (1) Japanese females exhibited GID traits more frequently than males and Japanese children exhibited GID traits less frequently than adolescents and adults (among females, the prevalence was 1.6% in children, 10% in adolescents, and 12% in adults; among males, the prevalence was 0.5, 2, and 3%, respectively); (2) the data did not support the prenatal hormone transfer theory for GID traits; and (3) a large part of the variance for GID traits in children was accounted for by familial factors; however, the magnitude was found to be greater in children than in adolescents or adults, particularly among females. This study suggests that although the prevalence is likely to increase, familial effects are likely to decrease as individuals age.

Digit ratio (2D:4D) is associated with breast cancer

Purpose: Digit ratio (2D:4D) has been considered as a proxy biomarker for prenatal hormonal exposure and may represent an individual’s predisposition to breast cancer. The purpose of the present study is to investigate whether there is a link between digit ratio and breast cancer in a Brazilian population. Methods: Digital measurements of the lengths of the index and ring fingers of both hands were obtained from women with breast cancer (n = 100) and age-matched controls (n = 100) using a digital Vernier calliper. Mean digit ratios of right hands, left hands, and right minus left hand 2D:4D (DR-L) were compared between both groups. Data were analysed by the Student's t -test for unpaired samples, Mann-Whitney test, and Spearman`s correlation with a significance level of 5%. Results: The patients with breast cancer presented significantly higher right and left 2D:4D (both p < 0.001) and higher DR-L ( p = 0.032) than controls. Among breast cancer cases, there was a significantly negative correlation between left 2D:4D and age diagnosed with breast cancer ( p = 0.018). Conclusion: Digit ratio offers a valid retrospective biomarker of action of prenatal hormones and might be associated with breast cancer risk and age at onset of breast cancer. It suggests that higher exposure or sensitivity to prenatal oestrogen might be associated with a higher risk of breast cancer and with earlier onset of the disease.

A Link Between Maternal Thyroid Hormone and Sexual Orientation?

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Sex differences in sports interest and motivation: An evolutionary perspective.

Although girls and women in many societies avidly participate in sports, they have been traditionally underrepresented compared with boys and men. In this review, we address the apparent sex differences in sports interest and motivation from an evolutionary perspective. First, we demonstrate that females’ underrepresentation generally reflects lesser interest, not merely fewer opportunities for engagement. Moreover, there is mounting evidence that male and female athletes generally differ in their motivation, specifically their competitiveness and risk taking. Second, we examine the functional explanations for sports. We argue that the courtship display hypothesis applies mainly to females; the spectator lek hypothesis applies chiefly to males; and that 2 other hypotheses—the allying with coalitions hypothesis and the development of skills hypothesis—are important for both females and males. Third, we explore the proximate causes for the sex differences in sports interest and motivation. We show that although there is compelling evidence that prenatal hormones contribute, the evidence that socialization plays a role remains equivocal. We conclude by discussing key findings and identifying areas for further research.

Individual Differences in Personality Masculinity-Femininity: Examining the Effects of Genes, Environment, and Prenatal Hormone Transfer

Males and females score differently on some personality traits, but the underlying etiology of these differences is not well understood. This study examined genetic, environmental, and prenatal hormonal influences on individual differences in personality masculinity-femininity (M-F). We used Big-Five personality inventory data of 9,520 Swedish twins (aged 27 to 54) to create a bipolar M-F personality scale. Using biometrical twin modeling, we estimated the influence of genetic and environmental factors on individual differences in a M-F personality score. Furthermore, we tested whether prenatal hormone transfer may influence individuals' M-F scores by comparing the scores of twins with a same-sex versus those with an opposite-sex co-twin. On average, males scored 1.09 standard deviations higher than females on the created M-F scale. Around a third of the variation in M-F personality score was attributable to genetic factors, while family environmental factors had no influence. Males and females from opposite-sex pairs scored significantly more masculine (both approximately 0.1 SD) than those from same-sex pairs. In conclusion, genetic influences explain part of the individual differences in personality M-F, and hormone transfer from the male to the female twin during pregnancy may increase the level of masculinization in females. Additional well-powered studies are needed to clarify this association and determine the underlying mechanisms in both sexes.

Differential susceptibility to the environment: Are developmental models compatible with the evidence from twin studies?

According to models of differential susceptibility, the same neurobiological and temperamental traits that determine increased sensitivity to stress and adversity also confer enhanced responsivity to the positive aspects of the environment. Differential susceptibility models have expanded to include complex developmental processes in which genetic variation interacts with exposure to early environmental factors, such as prenatal stress hormones and family conflict. In this study I employed a simulation approach to explore whether, and under what conditions, developmental models of differential susceptibility are compatible with the cumulative findings from twin studies of personality and behavior, which consistently show sizable effects of genetic and nonshared environmental factors and small to negligible effects of the shared environment. Simulation results showed that, to a first approximation, current alternative models of differential susceptibility are all equally compatible with the evidence from twin research; that sizable interaction effects involving individual differences in plasticity are plausible, but only if direct environmental effects are correspondingly weak; and that a major role of shared environmental factors is plausible in early development (consistent with the developmental mechanisms postulated in the differential susceptibility literature) but not in later development. These results support the general plausibility of differential susceptibility models and suggest some realistic constraints on their assumptions. (PsycINFO Database Record

Testosterone & gift-giving: Mating confidence moderates the association between digit ratios (2D:4D and rel2) and erotic gift-giving

While prenatal testosterone and estrogen have been associated with various masculinized traits such as risk-taking, aggression, athletic ability, and sex drive, little is known regarding the impact of prenatal hormones on male romantic gift-giving. In a sample of 130 Caucasian men, we investigate the association between digit ratios (2D:4D and rel2), a proxy of exposure to prenatal testosterone-to-estrogen ratio, and the likelihood of offering erotic gifts to romantic partners. We hypothesize that men with highly masculinized (low) digit ratios and high mating confidence (i.e., the self-perceived ease with which one gains sexual access to others) will engage in greater erotic gift-giving. We find that masculinized digit ratios are associated with greater erotic gift-giving, but only among men with high mating confidence. Our findings suggest that high prenatal testosterone exposure and high prenatal estrogen exposure are likely to promote a greater desire to offer erotic gifts to a romantic partner, but that only men with high mating confidence have the courage to act on these desires.

Participation in STEM Fields and 2d:4d in University Faculty

Success in the fields of science, technology, engineering, and mathematics (STEM) is dependent in part upon an individual’s cognitive ability in the areas of abstract mathematical reasoning and spatial reasoning. These abilities are related to prenatal hormone levels and can be estimated by measuring finger-size ratios. Specifically, the ratio between an individual’s second and fourth digits (2d:4d) is inversely related to prenatal androgen exposure. Smaller 2d:4d ratios are associated with higher scores on measures of abstract mathematical and spatial reasoning. Here we used a novel method for measuring 2d:4d. We digitally photographed and then measured ratios of university faculty members. We found that male university faculty in STEM fields exhibited smaller ratios than males in other academic fields (e.g., history, literature). On average, women within STEM fields exhibited a larger ratio than did women in other fields, indicating a wider variety of influences on their success in these fields. Our results suggest that prenatal androgen exposure likely plays a role in determining career path, but that success in STEM fields is

Autism Spectrum Disorder Risk in Relation to Maternal Mid-Pregnancy Serum Hormone and Protein Markers from Prenatal Screening in California.

We examined prenatal screening markers and offspring autism spectrum disorder (ASD) using California statewide data on singleton births in 1996 and 2002. Second trimester levels of unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and maternal serum alpha-fetoprotein (MSAFP) were compared between mothers of children with ASD (n = 2586) and of non-cases (n = 600,103). Adjusted odds ratios (AOR) were calculated by logistic regression. Lower uE3 (AOR for < 10th percentile vs. 25th-74th percentiles = 1.21, 95 % CI 1.06-1.37), and higher MSAFP (AOR = 1.21, 95 % CI 1.07-1.37 for > 90th percentile) were significantly associated with ASD. A U-shaped relationship was seen for hCG (AOR = 1.16, 95 % CI 1.02-1.32 for < 10th percentile; AOR = 1.19, 95 % CI 1.05-1.36 for > 90th percentile). Our results further support prenatal hormone involvement in ASD risk.

P.6.d.010 The 2D:4D digit ratio as biomarker for substance abuse

Purpose: The second (2D, index finger) to fourth (4D, ring finger) digit ratio is a biomarker for prenatal testosterone and estrogen exposure. It has been hypothesized that the developmental origins of health and behavior are modulated by the presence or absence of prenatal sex hormones. Several studies have shown a significant relationship between prenatal testosterone concentrations in amniotic fluid and adult risk taking behavior [1]. As the 2D:4D digit ratio does not change after the age of 2, it may be useful as screening tool for later life substance abuse [2]. The purpose of the current study was to investigate the 2D:4D digit ratio and its potential relationship with drug use and smoking. Methods: A survey was held among N= 1067 Dutch adults (57.6% men), aged 16-55 years old (mean age 23.8 years old). For both hands, digit lengths of the second (2D, index finger) and fourth (4D, ring finger) finger were measured using digital vernier calipers recording to 0.01 mm. Measurements were made from the mid-point of the finger crease proximal to the palm to the tip of the finger. Demographics, smoking status (yes/no) and daily number of cigarettes smoked were recorded. Past year's drug use was rated as (1) never, (2) seldom (1-2 times), (3) now and then (3-11 times), monthly, weekly, or daily. Non-parametric correlations were computed to examine the relationship of the 2D:4D digit ratio with alcohol, drug use, and smoking. In addition, substance use of subjects with a hawk-type (2D:4D 1) were compared. Results: Overall, the left 2D:4D digit ratio correlated significantly with frequency of drug use (r = -0.095, p = 0.003). The right 2D:4D digit ratio correlated significantly with the number of cigarettes smoked (r = -0.092, p = 0.005) and the frequency of drug use (r = -0.125, p = 0.0001). For men, the left 2D:4D digit ratio correlated significantly with frequency of drug use (r = -0.125, p = 0.003). The right 2D:4D digit ratio in men correlated significantly with the number of cigarettes smoked (r = -0.127, p = 0.003) and the frequency of drug use (r = -0.141, p = 0.001). For women, none of the correlations between substance abuse and digit ratio were significant. Subjects with a right 2D:4D1. They also significantly more often were drug users (p = 0.004, 33.6% of hawks versus 24.3% of doves). Conclusion: Subjects with a 2D:4D1. Although the strength of the associations is modest, subjects with a lower 2D:4D digit ratio tend to smoke more cigarettes and use drugs of abuse more frequently.

Effects of Prenatal Environment on Phenotype Are Revealed by Postnatal Challenges: Embryonic Hormone Exposure, Adrenocortical Function, and Food in Seabird Chicks.

The interaction between prenatal environments and postnatal environments is an important source of phenotypic variability. We examined the ability of prenatal steroid exposure and postnatal energy restriction to explain adrenocortical function and fledging age in captive seabird chicks. We proposed and tested two hypotheses: (1) the strength of prenatal effects is attenuated by challenging postnatal environments (postnatal override) and (2) the strength of prenatal effects increases with the severity of postnatal challenges (postnatal reveal). We reared common murre (Uria aalge) chicks and measured prenatal exposure to corticosterone (CORT) and testosterone (T) from allantoic waste. Adrenocortical function was assessed after 10 d of ad lib. feeding and then after 5 and 10 d on controlled diets. Postnatal override predicts that prenatal steroids will explain more phenotypic variation before implementation of energy restriction; postnatal reveal predicts that the contribution of prenatal steroids will increase with duration and severity of energy restriction. Energy restriction increased secretion of baseline CORT and the adrenocortical response to the standardized stressor of handling and restraint. The ability of prenatal steroids to explain baseline CORT increased with duration of energy restriction, and for day 20 free baseline CORT, there was a significant interaction between kilojoules per day and prenatal CORT levels; severity of restriction strengthened the relationship between prenatal hormone levels and postnatal hormone levels. Both maximum CORT at day 20 and fledging age were best explained by diet treatment and day 15 or day 20 baseline CORT, respectively. Overall, prenatal CORT increased fledging age and baseline secretion of CORT, while prenatal T decreased them. However, prenatal effects on adrenocortical function were apparent only under the energy restriction conditions. Thus, we found some support for the postnatal reveal hypothesis; our results suggest that some prenatal effects on phenotype may be more likely to manifest in challenging postnatal environments.

Differential Effects of Maternal Yolk Androgens on Male and Female Offspring: A Role for Sex-Specific Selection?

Maternal hormones are important mediators of prenatal maternal effects in animals. Although their effects on offspring phenotype are often sex-specific, the reason why sometimes sons are more sensitive to prenatal hormone exposure and sometimes daughters is not well understood. Here I combine an experimental manipulation of yolk testosterone concentration in the egg and quantification of selection acting on yolk androgen-sensitive traits in a natural population of great tits (Parus major) with a literature review to test the hypothesis that sex-specific selection on traits affected by yolk androgens determines which sex is more sensitive to prenatal hormone exposure. An experimental increase of the testosterone content in the egg boosted the post-hatching growth of male, but not female great tit nestlings. However, I found no evidence that survival selection on body mass or size is acting differently in the two sexes. A literature review revealed that yolk androgen manipulations affect the growth of males and females differently across species. Interestingly, in studies performed in the wild a significant association between the strength and direction of sexual size dimorphism and sex-specific sensitivities to yolk androgens was observed. In studies performed in captivity, no such relationship was found. Thus, across species there is some evidence that sex-specific selection on body size influences how strongly growth trajectories of males and females are affected by maternally-derived yolk androgens.

Second to fourth digit ratio (2D:4D) and coronary heart disease

IntroductionSex steroid exposure during human development may influence disease susceptibility. Second to fourth digit ratio (2D:4D) is thought to be a putative biomarker for prenatal hormone level during foetal life. Recently there has been a great deal of interest in 2D:4D and risk of disease in adulthood. MethodsWe explored the relationship between 2D:4D ratio and coronary heart disease. Photocopies of the two hands of 310 males (controls: 155; patients: 155) were collected at Yin chuan city, in the Ningxia province of China. Left hand, right hand, mean hand and right minus left 2D:4D (Dr-l) were analysed. ResultsThe mean values of 2D:4D ratio in patients were higher than those of CSIN controls. The patients showed significantly higher 2D:4D (left hand: P<0.01; right hand, mean hand: P<0.05) than controls. In patients, 2D:4D (especially left hand 2D:4D) were inversely associated with age at diagnosis (left hand: P<0.001; right hand, mean hand: P<0.05). No association between Dr-l and age or age at presentation of disease was observed in the groups. Conclusion2D:4D may correlate particularly with risk of coronary heart disease in Chinese men.