Unexplained repeated pregnancy loss is associated with altered perceptual and brain responses to men’s body-odor

Mammalian olfaction and reproduction are tightly linked, a link less explored in humans. Here, we asked whether human unexplained repeated pregnancy loss (uRPL) is associated with altered olfaction, and particularly altered olfactory responses to body-odor. We found that whereas most women with uRPL could identify the body-odor of their spouse, most control women could not. Moreover, women with uRPL rated the perceptual attributes of men's body-odor differently from controls. These pronounced differences were accompanied by an only modest albeit significant advantage in ordinary, non-body-odor-related olfaction in uRPL. Next, using structural and functional brain imaging, we found that in comparison to controls, most women with uRPL had smaller olfactory bulbs, yet increased hypothalamic response in association with men's body-odor. These findings combine to suggest altered olfactory perceptual and brain responses in women experiencing uRPL, particularly in relation to men's body-odor. Whether this link has any causal aspects to it remains to be explored.


Sample-size estimation
• You should state whether an appropriate sample size was computed when the study was being designed • You should state the statistical method of sample size computation and any required assumptions • If no explicit power analysis was used, you should describe how you decided what sample (replicate) size (number) to use Please outline where this information can be found within the submission (e.g., sections or figure legends), or explain why this information doesn't apply to your submission:

Replicates
• You should report how often each experiment was performed • You should include a definition of biological versus technical replication • The data obtained should be provided and sufficient information should be provided to indicate the number of independent biological and/or technical replicates • If you encountered any outliers, you should describe how these were handled • Criteria for exclusion/inclusion of data should be clearly stated • High-throughput sequence data should be uploaded before submission, with a private link for reviewers provided (these are available from both GEO and ArrayExpress) Please outline where this information can be found within the submission (e.g., sections or figure legends), or explain why this information doesn't apply to your submission: Detailed information regarding sample size estimation can be found in the methods section. We conducted a power analysis for the main experiment (identification of spouse) which concluded a sample size of 29 subjects per group, therefore we recruited a pool of at least 30 participants per group for the entire set of studies. We matched the number of control women in each task to that of the RPL women. The number of women in each group, per experiment/task, is described in the main article, both in the results section (including main text and figure legends) and in the methods section. Information regarding performance of experiments and timing, repetitions, outliers, exclusion and inclusion of subjects and/or data can all be found in the methods section. Pre-study exclusions were as followed: for RPL group, women who don't experience a natural menstrual cycle. For control group, the same criteria as RPL was applied. In addition, women who experienced any type of pregnancy loss, including an abortion or ectopic pregnancy were excluded from the control group. During data analyses, for each test, participants with Z-scores higher or lower than 2.7 STD from group's mean were excluded.

Statistical reporting • Statistical analysis methods should be described and justified
• Raw data should be presented in figures whenever informative to do so (typically when N per group is less than 10) • For each experiment, you should identify the statistical tests used, exact values of N, definitions of center, methods of multiple test correction, and dispersion and precision measures (e.g., mean, median, SD, SEM, confidence intervals; and, for the major substantive results, a measure of effect size (e.g., Pearson's r, Cohen's d) • Report exact p-values wherever possible alongside the summary statistics and 95% confidence intervals. These should be reported for all key questions and not only when the p-value is less than 0.05.
Please outline where this information can be found within the submission (e.g., sections or figure legends), or explain why this information doesn't apply to your submission: (For large datasets, or papers with a very large number of statistical tests, you may upload a single table file with tests, Ns, etc., with reference to sections in the manuscript.)

Group allocation
• Indicate how samples were allocated into experimental groups (in the case of clinical studies, please specify allocation to treatment method); if randomization was used, please also state if restricted randomization was applied • Indicate if masking was used during group allocation, data collection and/or data analysis Please outline where this information can be found within the submission (e.g., sections or figure legends), or explain why this information doesn't apply to your submission: Additional data files ("source data") • We encourage you to upload relevant additional data files, such as numerical data that are represented as a graph in a figure, or as a summary table • Where provided, these should be in the most useful format, and they can be uploaded as "Source data" files linked to a main figure or table • Include model definition files including the full list of parameters used • Include code used for data analysis (e.g., R, MatLab) • Avoid stating that data files are "available upon request" Please indicate the figures or tables for which source data files have been provided: Statistical analysis methods, tests, assumptions and corrections, parameters, exact pvalues, and effect sizes, can all be found both in the results section and methods section in the main paper. We show all individual participants in the graphs, even though well over 10.
Research samples in this study are comprised of two groups of women: women who experienced unexplained recurrent pregnancy losses (RPL), and women who never experienced a pregnancy loss (Controls), matched by age. All women in RPL group underwent clinical investigations independent of the present study, and were defined to have no known reason for their pregnancy losses. Due to the nature of the study, no randomization was applied for subject selection. We did, however, randomize stimuli order within experiments, and counter-balanced conditions across subjects. This information can be found in the methods section.