Anna Ziomkiewicz

Large breasts and narrow waists indicate high reproductive potential in women

Physical characteristics, such as breast size and waist–to–hip ratio (WHR), function as important features used by human males to assess female attractiveness. Males supposedly pay attention to these features because they serve as cues to fecundity and health. Here, we document that women with higher breast–to–underbreast ratio (large breasts) and women with relatively low WHR (narrow waists) have higher fecundity as assessed by precise measurements of daily levels of 17–β–oestradiol (E2) and progesterone. Furthermore, women who are characterized by both narrow waists and large breasts have 26% higher mean E2 and 37% higher mean mid–cycle E2 levels than women from three groups with other combinations of body–shape variables, i.e. low WHR with small breasts and high WHR with either large or small breasts. Such gains in hormone levels among the preferred mates may lead to a substantial rise in the probability of conception, thus providing a significant fitness benefit.

Habitual physical activity and estradiol levels in women of reproductive age.

Variation in the risk of breast cancer observed among women and among populations may be explained by variation in lifetime exposure to estrogens. The suppressive effect of exercise on estradiol levels in women is well documented, but it is unknown whether habitual (i.e. typical daily) physical activity has a similar effect. Epidemiological data suggest that physical activity is one of the few modifiable factors capable of reducing the risk of breast cancer in women. We investigated whether variation in the amount of habitual activity corresponds to variation in estradiol levels in women of reproductive age. One hundred and thirty-nine regularly menstruating women 24–37 years of age collected daily saliva samples for one complete menstrual cycle and kept a daily log of physical activity. Saliva samples were analyzed for concentration of estradiol. We observed a negative relationship between habitual physical activity and salivary levels of estradiol. Mean estradiol was 21.1 pmol/l in the low, 17.9 pmol/l in the moderate and 16.6 pmol/l in the high activity group (all pairwise differences were statistically significant at P<0.009). A strong association exists between physical activity and levels of estradiol among women of reproductive age. A modern lifestyle, characterized by reduced physical activity, may therefore contribute to a rise in the levels of estradiol produced during menstrual cycles and thus to higher cumulative lifetime exposure to estradiol, resulting in a higher risk of breast cancer.

Body fat, energy balance and estradiol levels: a study based on hormonal profiles from complete menstrual cycles

BACKGROUND Female fecundity is regulated by nutritional status. Although widely cited, this hypothesis is not strongly supported by empirical data from non-obese, healthy women of reproductive age. METHODS Healthy, reproductive aged women (n = 141) from Southern Poland collected daily morning saliva samples for one complete menstrual cycle. Levels of 17-beta-estradiol were analyzed by radioimmunoassay. Anthropometric measurements, including body fat percentage, were taken randomly with respect to phase of the menstrual cycle. Energy balance was specified based on changes in body fat percentage from the beginning to the end of the observation period. RESULTS Women with very low and high body fat had significantly lower levels of E2 compared with women with low and average body fat. In women of very low to average body fat, a 10% increase in body fat was associated with a 5-7 pmol/l increase in estradiol levels. The association between fat percentage and E2 was even stronger in women with positive energy balance, who also showed significant differences between body fat groups in estradiol profiles across whole the menstrual cycle. No such relationship was found in women with negative energy balance. CONCLUSIONS In healthy women, we found a non-linear association between body fat and estradiol levels. Both very low and high body fat was associated with decreased estradiol levels. The relationship between estradiol and body fat was strongly influenced by womens energy balance.

Relationships between biomarkers of inflammation, ovarian steroids, and age at menarche in a rural polish sample

To test the hypothesis that life history trade‐offs between maintenance and reproductive effort would be evident through inverse associations between levels of a biomarker of inflammation [C‐reactive protein (CRP)], and ovarian hormones. Associations between CRP and age at menarche were also explored.

CYP17 genotypes differ in salivary 17-β estradiol levels: A study based on hormonal profiles from entire menstrual cycles

Variation in the levels of sex-steroid hormones results from differences in developmental conditions, adult lifestyle, and genetic polymorphism. Genes involved in sex-steroid biosynthesis have been implicated to influence levels of hormones in premenopausal women, but the results were inconclusive. We tested variation among women in levels of salivary estradiol (E2) corresponding to CYP17 genotypes. CYP17 encodes cytochrome P450c17α, which mediates two enzymes important in E2 synthesis. In contrast to the earlier studies that relied on one or a few samples for assessing the E2 levels of an individual woman, our study is based on daily collected saliva samples for one entire menstrual cycle. Sixty Polish women, ages 24 to 36 years, with regular menstrual cycles and no reported fertility problems participated in the study. Women with A2/A2 genotype had 54% higher mean E2 levels than women with A1/A1 genotype (P = 0.0001) and 37% higher than women with A1/A2 genotype (P = 0.0008). Heterozygous A1/A2 women had 13 % higher E2 levels than homozygous A1/A1 women (but this difference was significant only in a nonparametric test). Levels of E2 during the day with highest E2 (day −1) were 72% higher in A2/A2 compared with A1/A1 (P = 0.01) and 52 % higher compared with A1/A2 (P = 0.03). Our results suggest that CYP17 genotype may serve as a biomarker of endocrine function in women of reproductive age. (Cancer Epidemiol Biomarkers Prev 2006;15(11):2131–5)

Menstrual Synchrony: Fact or Artifact?

Although more than thirty years of intensive investigation have passed since McClintock first published results on menstrual synchrony, there is still no conclusive evidence for the existence of this phenomenon. Indeed, a growing body of nullresult studies, critiques of menstrual synchrony studies, and the lack of convincing evolutionary explanations bring into question the existence of this phenomenon. This paper presents results of a study conducted over five consecutive months in Polish student dormitories. In 18 pairs and 21 triples of college-age women, menstrual synchrony was not found. Social interactions, considered the most important factor mediating the effect of menstrual synchrony, was unrelated to any difference in menstrual cycle onsets. Initial menstrual onset difference was influenced by woman’s body mass and menstrual cycle irregularity. These results provide further evidence that women do not synchronize their menstrual cycles.

Apolipoprotein E (ApoE) polymorphism is related to differences in potential fertility in women: a case of antagonistic pleiotropy?

The alleles that are detrimental to health, especially in older age, are thought to persist in populations because they also confer some benefits for individuals (through antagonistic pleiotropy). The ApoE4 allele at the ApoE locus, encoding apolipoprotein E (ApoE), significantly increases risk of poor health, and yet it is present in many populations at relatively high frequencies. Why has it not been replaced by natural selection with the health-beneficial ApoE3 allele? ApoE is a major supplier of cholesterol precursor for the production of ovarian oestrogen and progesterone, thus ApoE has been suggested as the potential candidate gene that may cause variation in reproductive performance. Our results support this hypothesis showing that in 117 regularly menstruating women those with genotypes with at least one ApoE4 allele had significantly higher levels of mean luteal progesterone (144.21 pmol l−1) than women with genotypes without ApoE4 (120.49 pmol l−1), which indicates higher potential fertility. The hormonal profiles were based on daily data for entire menstrual cycles. We suggest that the finding of higher progesterone in women with ApoE4 allele could provide first strong evidence for an evolutionary mechanism of maintaining the ancestral and health-worsening ApoE4 allele in human populations.

Temperament and ovarian reproductive hormones in women: Evidence from a study during the entire menstrual cycle

Personality and temperament were hypothesized to function as important factors affecting life history strategies. Recent research has demonstrated the association between temperamental traits and reproduction in humans, however, the underlying mechanisms are still poorly understood. This study presents evidence for an association between temperamental traits and womans fecundity, as indicated by levels of ovarian steroid hormones during the menstrual cycle. On a large sample of urban, reproductive age women (n = 108) we demonstrated that activity, endurance and emotional reactivity are associated with levels of estrogen and with a pattern of change of progesterone levels. Women high in activity, high in endurance and low in emotional reactivity had up to twice as high estradiol levels and more favorable progesterone profiles as women low in activity, low in endurance and high in emotional reactivity. The temperamental traits we measured highly overlap with extraversion, neuroticism and negative emotionality that were reported to correlate with reproductive success. Our findings thus suggest a possible explanation for these relationships, linking personality and womens reproductive success through a hormonal pathway.

Higher luteal progesterone is associated with low levels of premenstrual aggressive behavior and fatigue

Contradictory findings show both positive and negative effect of progesterone on the premenstrual mood changes in women. Here we present the study investigating this relationship on the large sample of premenstrual women. 122 healthy, reproductive age women collected daily morning saliva samples and recorded intensity scores for the mood symptoms: irritability, anger, sadness, tearfulness, insomnia, and fatigue. Saliva samples were assayed for progesterone concentrations and mood intensity scores were used to calculate behavioral indices. Women with low Aggression/Irritability and Fatigue had consistently higher progesterone levels during the luteal phase than women with high Aggression/Irritability and Fatigue. Additionally, Aggression/Irritability and Fatigue correlated negatively with maximal progesterone value during the luteal phase. Our results demonstrated a negative effect of low progesterone level on the premenstrual mood symptoms such as aggressive behavior and fatigue in healthy reproductive age women. This supports a previously proposed model of biphasic action of progesterone metabolites on mood.

Digit ratio (2D

Second‐to‐fourth digit ratio (2D:4D) is proposed as a proxy for the prenatal balance of sex hormones, is related to hormone‐dependent characteristics in adult life, and is a possible predictor of disease later in life. Here, we studied the relationship between 2D:4D and ovarian steroid hormones (17β‐estradiol and progesterone) among women of reproductive age.