Couples having trouble conceiving are often given one piece of advice: just relax and it will happen. But does scientific evidence support this advice? Our recent study from the Boston University School of Public Health indicates that stress, particularly among females, may indeed be involved in the etiology of infertility.
Our research team used data from Pregnancy Study Online (PRESTO), a web-based cohort study of couples trying to conceive, to study the association between stress and fertility. We enrolled 4,769 women and 1,272 of their male partners. All participants resided in the United States or Canada and had been trying to conceive naturally, without the use of fertility treatment, for six or fewer cycles at enrollment.
Participants completed online baseline questionnaires to ascertain information on demographics (for example, age, race/ethnicity, and education level), behaviors (for example, cigarette smoking and alcohol intake), and medical factors (for example, height and weight, history of chronic health conditions, and medication use). Women additionally completed bi-monthly follow-up questionnaires to report on whether or not they had conceived since their previous questionnaire.
We measured stress using the Perceived Stress Scale (PSS), a 10-item questionnaire designed to assess how unpredictable, uncontrollable, and overwhelming individuals find their life circumstances. The PSS is considered a better measure of stress than objective assessments of stressful events because it incorporates an individual’s cognitively-mediated response to stress, and thus accounts for the fact that people respond to stressful situations in different ways. We collected PSS scores at baseline for women and men, and at each follow-up for women only.
We found that women with PSS scores >25 (on a scale of 0-40) had 13% lower chances of conceiving in a given menstrual cycle compared with women with PSS scores <10. These results account for factors potentially associated with both stress and fertility, including age, race/ethnicity, education, income, and body mass index. PSS scores in men, on the other hand, were not meaningfully associated with the likelihood of conception. We also found that fertility was lowest among women with high PSS scores who had partners with low PSS scores. Although these results may reflect chance variation, they could also indicate that partner stress discordance may play a role.
There are several biologic hypotheses as to how stress can affect fertility. It can alter hormonal function and may delay or inhibit the luteinizing hormone surge of the menstrual cycle. It may also interfere with implantation or reduce the number of viable eggs in the ovary. While we were not able to directly assess these hypotheses in our study, we did find that a small proportion of the association between stress and fertility may be due to reduced intercourse frequency and increased risk of irregular cycles. This indicates that altered behaviors and menstrual function due to stress may explain part of the association.
While this study does not definitively prove that stress causes infertility, it does provide evidence supporting this hypothesis and suggests a role for mental health counseling in preconception guidance and care. Future studies measuring stress at varying time points (for example, chronic stress or stress during particular windows of susceptibility, such as the fertile window) and intervention studies of stress reduction techniques during preconception may further clarify the role of stress in the etiology of infertility.
PRESTO is an ongoing study that is actively recruiting couples attempting to conceive. If you are interested in participating or learning more about the study, please visit our study website at http://presto.bu.edu.