Hormonal mechanisms and the optimal use of luteinizing hormone tests in human menstrual cycle research.

Tests of whether women's psychology or behavior shifts during the fertile window vs. other cycle phase regions often employ a design in which fertile window test sessions are scheduled after a positive urinary luteinizing hormone (LH) test result. Lobmaier and Bachofner (2018) point out that this design will schedule high fecundity test sessions at the very end of the fertile window, if not later, when fecundity is not at its highest. I agree with their arguments, and here argue that the problems with this scheduling technique appear even more severe if one considers the hormonal mechanisms that are the likely regulators of cycle phase shifts. Test sessions scheduled after positive LH tests will occur at a time of rapid transitions in hormone production and will often systematically exclude periovulatory days with the highest concentrations of important hormones, such as estradiol. In doing so, this method may often fail to detect cycle phase shifts that are regulated by changes in these hormones. Hypothesis testing in cycle phase research can be improved via a transition from thinking of "fertility" as a discrete and monolithic variable, to instead thinking about the predicted effects of more continuous hormonal signals. I conclude with some general thoughts about how LH tests may be used more productively in studies of cycle phase shifts in psychology and behavior.

Timing is crucial: Some critical thoughts on using LH tests to determine women's current fertility.

Naturally cycling women reportedly go through a variety of psychological and behavioural changes over menstrual cycle. Evolutionary informed scholars have interpreted such changes as maximising reproductive success. However, concerns have been raised regarding this ovulatory shift hypothesis, since recent studies have yielded inconsistent findings. We suggest that the inconsistent findings regarding the ovulatory shift hypothesis may result from a too simplistic definition of the fertile window. Presently, most studies use LH tests to determine the fertile window. The problem with this "gold standard" is that it builds on the misconception that fertility peaks with ovulation and that ovulation regularly occurs 24 to 48 hours after the LH surge. While commercially available urinary LH test strips are a cheap and easy way to reliably detect LH surges, the LH surge itself marks the impending end of the fertile window. So if women are invited to the laboratory after the LH surge (as is often done for practical reasons) there is a high probability of misclassifying women as fertile when in fact the fertile window has already closed. We discuss possible advancements that may help to increase the accuracy and reliability of determining a woman's individual fertile window, during which any adaptive changes that increase the chance of reproduction should be best observable.

Menstrual cycle phase predicts women's hormonal responses to sexual stimuli.

A robust body of research has demonstrated shifts in women's sexual desire and arousal across the menstrual cycle, with heightened desire and arousal coincident with heightened probability of conception (POC), and it is likely that ovarian hormones modulate these shifts. However, studies in which women are exposed to audiovisual sexual stimuli (AVSS) at high POC (mid-follicular) and low POC (luteal) phases have failed to detect significant differences in genital or subjective arousal patterns based on menstrual cycle phase. Here, we tested whether hormonal responsivity to AVSS differs as a function of cycle phase at testing, and whether phase during which participants were first exposed to AVSS influences hormonal responsivity in subsequent test sessions. Twenty-two naturally cycling heterosexual women were exposed to AVSS during the follicular and luteal phases, with phase at first test session counterbalanced across participants. Salivary samples were collected before and after AVSS exposure. Estradiol increased significantly during both follicular and luteal phase sessions, and increases were higher during the follicular phase. Testosterone (T) increased significantly only during the follicular phase session, while progesterone (P) did not change significantly during either cycle phase. Session order and current cycle phase interacted to predict P and T responses, such that P and T increased during the follicular phase in women who were first tested during the luteal phase. These data suggest that menstrual cycle phase influences hormonal responsivity to AVSS, and contribute to a growing body of clinical and empirical literature on the neuroendocrine modulators of women's sexuality.

Standardized protocols for characterizing women's fertility: A data-driven approach.

Experts are divided on whether women's cognition and behavior differs between fertile and non-fertile phases of the menstrual cycle. One of the biggest criticisms of this literature concerns the use of indirect, imprecise, and flexible methodologies between studies to characterize women's fertility. To resolve this problem, we provide a data-driven method of best practices for characterizing women's fertile phase. We compared the accuracy of self-reported methods and counting procedures (i.e., the forward- and backward-counting methods) in estimating ovulation using data from 140 women whose fertility was verified with luteinizing hormone tests. Results revealed that no counting method was associated with ovulation with >30% accuracy. A minimum of 39.5% of the days in the six-day fertile window predicted by the counting methods were non-fertile, and correlations between counting method conception probabilities and actual conception probability were weak to moderate, rs=0.11-0.30. Poor results persisted when using a lenient window for predicting ovulation, across alternative estimators of the onset of the next cycle, and when removing outliers to increase the homogeneity of the sample. By contrast, combining counting methods with a relatively inexpensive test of luteinizing hormone predicted fertility with accuracy >95%, but only when specific guidelines were followed. To this end, herein we provide a cost-effective, pragmatic, and standardized protocol that will allow researchers to test whether fertility effects exist or not.

Efficacy of methods for ovulation estimation and their effect on the statistical detection of ovulation-linked behavioral fluctuations.

Contention of the ovulatory shift hypothesis is principally supported by failures to replicate previous findings; e.g., recent meta-analytic work suggests that the effects endorsing the hypothesis may not be robust. Some possible limitations in this and other ovulatory-effects research-that may contribute to such controversy arising-are: (a) use of error-prone methods for assessing target periods of fertility that are thought to be associated with behavioral shifts, and (b) use of between-subjects-as opposed to within-subjects-methods. In the current study we present both simulated and empirical research: (a) comparing the ability of between- and within-subject t-tests to detect cyclical shifts; (b) evaluating the efficacy of correlating estimated fertility overlays with potential behavioral shifts; and (c) testing the accuracy of counting methods for identifying windows of cycle fertility. While this study cannot assess whether the ovulatory shift hypothesis or other ovulatory-based hypotheses are tenable, it demonstrates how low power resulting from typical methods employed in the extant literature may be associated with perceived inconsistencies in findings. We conclude that to fully address this issue greater use of within-subjects methodology is needed.

A Mid-Cycle Rise in Positive and Drop in Negative Moods among Healthy Young Women: A Pilot Study.

Clinically oriented studies of mood as a function of the menstrual cycle mainly address the negative moods in the premenstrual phase of the cycle. However, a periovulatory increase in positive emotions and motivations related to reproduction has also been noted. Thus, it has been suggested that the drop in mood during the luteal phase of the menstrual cycle might be a byproduct of elevated positive moods occurring mid-cycle. The aim of this prospective study was to compare both the positive and negative dimensions of mood across the menstrual cycle. A group of 60 healthy, normally cycling women assessed their mood throughout three phases of their menstrual cycles: the early follicular (low estradiol and progesterone), the late follicular (fertile phase; high estradiol, low progesterone) and the mid-luteal phase (high levels of both estradiol and progesterone). Repeated MANOVA evaluations showed a significant increase in positive (friendly, cheerful, focused, active) and a significant decrease in negative (anxious, depressed, fatigued, hostile) dimensions of mood mid-cycle, i.e., during the late follicular phase (η2 = 0.072−0.174, p < 0.05). Contrary to the widespread belief that negative moods are characteristic of the luteal phase (preceding the onset of the next cycle), the post hoc Bonferroni tests showed that none of the mood dimensions differed between the mid-luteal and early follicular phases of the cycle. The results held when controlling for relationship status and order of testing. This pattern of fluctuations is in accordance with the ovulatory-shift hypothesis, i.e., the notion that the emotions of attraction rise during a short window during which the conception is likely.

The role of hormones in attraction and visual attention to facial masculinity.

The current study investigated the ovulatory shift hypothesis, which suggests that women prefer more masculine traits when estradiol is high, and progesterone is low (E/P ratio). The current study used an eye tracking paradigm to measure women's visual attention to facial masculinity across the menstrual cycle. Estradiol (E) and progesterone (P) were collected to determine if salivary biomarkers were associated with visual attention to masculine faces in a short- and long-term mating context. Women (N = 81) provided saliva samples at three time points throughout their menstrual cycle and were asked to rate and view men's faces that had been manipulated to appear feminine and masculine. Overall, masculine faces were viewed longer compared to feminine faces and this was moderated by mating context, where women viewed masculine faces longer for a long-term relationship. There was not any evidence suggesting that E/P ratio was associated with preferences for facial masculinity, but there was evidence to suggest that hormones were associated with visual attention to men in general. In line with sexual strategies theory, there was evidence to suggest that mating context and facial masculinity are important in mate choice; however, there was no evidence to suggest that women's mate choice was associated with shifts across the menstrual cycle.

Current Fertility Status Does Not Predict Sociosexual Attitudes and Desires in Normally Ovulating Women.

Previous research has found that women at peak fertility show greater interest in extra-pair sex. However, recent replications have failed to detect this effect. In this study, we add to this ongoing debate by testing whether sociosexuality (the willingness to have sex in the absence of commitment) is higher in women who are at peak fertility. A sample of normally ovulating women (N = 773) completed a measure of sociosexuality and had their current fertility status estimated using the backward counting method. Contrary to our hypothesis, current fertility was unrelated to sociosexual attitudes and desires, even when relationship status was included as a moderator. These findings raise further doubts about the association between fertility and desire for extra-pair sex.

Ovulatory Shifts in Sexual Desire But Not Mate Preferences: An LH-Test-Confirmed, Longitudinal Study.

The presented data are part of a longitudinal within-subject study designed to examine ovulatory shifts in human sexuality in a diverse German sample using validated questionnaires. The final sample consists of 78 individuals (76 female, 2 agender) who declared to be mainly or exclusively attracted to males. Questionnaires were completed anonymously online at three cycle phases. Following the gold standard, the fertile window was calculated through the reverse cycle day method and confirmed via urinary tests detecting luteinizing hormone. The questionnaire included the Sexual Desire Inventory, Dresdner Body Image Inventory, the Revised Sociosexual Orientation Inventory, and an adjective list to measure mate preferences. One hundred eighty-four questionnaires were included in the data analysis using linear mixed models. Findings support previous research reporting heightened sexual desire and an improved body image during the fertile window. No shifts were found for mate preference or sociosexual orientation, thus adding to a growing body of literature contesting parts of the ovulatory shift hypothesis.

Confounds in "Failed" Replications.

Reproducibility is essential to science, yet a distressingly large number of research findings do not seem to replicate. Here I discuss one underappreciated reason for this state of affairs. I make my case by noting that, due to artifacts, several of the replication failures of the vastly advertised Open Science Collaboration's Reproducibility Project: Psychology turned out to be invalid. Although these artifacts would have been obvious on perusal of the data, such perusal was deemed undesirable because of its post hoc nature and was left out. However, while data do not lie, unforeseen confounds can render them unable to speak to the question of interest. I look further into one unusual case in which a major artifact could be removed statistically-the nonreplication of the effect of fertility on partnered women's preference for single over attached men. I show that the "failed replication" datasets contain a gross bias in stimulus allocation which is absent in the original dataset; controlling for it replicates the original study's main finding. I conclude that, before being used to make a scientific point, all data should undergo a minimal quality control-a provision, it appears, not always required of those collected for purpose of replication. Because unexpected confounds and biases can be laid bare only after the fact, we must get over our understandable reluctance to engage in anything post hoc. The reproach attached to p-hacking cannot exempt us from the obligation to (openly) take a good look at our data.

Testosterone, the progesterone/estradiol ratio, and female ratings of masculine facial fluctuating asymmetry for a long-term relationship.

Idiosyncratic variation within the normal range of androgens levels in women account for significant variations in personality and behavior. We studied if testosterone introduces significant biases in women's perception of fluctuating symmetry of male faces suitability for a long-term relationship. Participants were 145 female college students asked to rate in a two-choice forced paradigm the attractiveness, suitability as a long-term partner, and economic success, fatherliness and fidelity of an asymmetric and a symmetric male face. Since our sample consists of random women interested in participating, whether for personal reasons or because they were paid to participate, we controlled for menstrual phase. All participants provided salivary samples to determine testosterone (T), estradiol (E2) and progesterone (P4) levels. When the P4/E2 was low and T low-to-normal, the symmetric face was rated as more attractive, and a desirable long-term partner, but these preferences changed to the opposite when P4/E2 was high. In high T women, neither face was rated as more attractive, independently from the P4/E2 ratio, but the asymmetric face was preferred as a long-term partner when conception risk was high, changing to prefer the symmetric face as the P4/E2 increased. The overall perception of male faces was that the symmetric face was more economical successful but a poor parent and highly unfaithful compared to the asymmetric face. A significant interaction between T and P4/E2 for ratings success of the asymmetric face suggests that high levels of feminine T might be related to inter-sexual competition when conception risk is high.