While working on our book, we developed a hunch that some couples that were taking longer than expected to get pregnant had more of a scheduling problem than a medical problem. Work was usually the culprit, combined with the epidemic of busyness that is raging through our society. We talked to some couples whose jobs required them to sleep apart because of travel or differing work schedules, or just left them completely exhausted much of the time. We wondered if busyness and work stress led to less frequent sex, which led to perceived infertility problems. Which could then lead to more stress.
It also made us wonder how often people actually had sex. Some national surveys have examined the frequency of sex among married and cohabitating couples, and how this changes over time, without looking at fertility intentions. These studies have suggested that married couples in their 30s and 40s have intercourse less frequently than those in their 20s. This is, of course, a cliché in the popular culture and has a shorthand, DINS, in the social science literature (double income no sex), and it is dependent on the length of the relationship and other factors. However, the differences found between older and younger couples do not seem large enough to effect fertility. For example, one study found that married people aged 25-29 had sex about 10 times per month, compared with about 8 times per month for those 35-44.
More relevant are studies that included only couples that were trying to conceive. One Danish study enrolled women who were trying to conceive, were less than 40 years old and without history of infertility. Researchers maintained contact with them for one year or until they became pregnant, whichever was sooner. Among women less than age 25, 31% had intercourse four or more times per week, compared with 21% of women aged 25-29 and 15% of women in their thirties. However, the study showed little influence of sexual frequency on fecundity (the probability of getting pregnant), in terms of determining who conceived and who didn’t.
Also, most researchers have hypothesized things differently than we did. Treating infertile couples has led many researchers to suspect that infertility leads to stress, depression, anxiety, viewing sex like a chore, or a combination of these factors, and that this leads to less frequent sex. This would then compound any physiological problems that reduced fertility.
Several studies bear this out, to some extent. In one example, 25% of men seeking care at an infertility clinic reported having intercourse less than 4 times per month, while most men in the study reported having sex more than 5 times per month. Five + times per month compares to the national average - but don’t you think couples trying to get pregnant should try to be a bit above average in this regard?
Other studies have also suggested that infertility could be associated with male sexual difficulties, such as premature ejaculation and erectile dysfunction. The requirement to perform for infertility tests and treatments creates anxiety in many men. Men are not the only ones facing difficulties. Women experiencing infertility generally report less satisfaction with their sex lives, although this is not always found to be true. Surveys attempt to measure this by asking women about their satisfaction related to sexual desire, arousal, and orgasm and whether this these issues cause them to feel distressed; some studies also assess pain during intercourse. Surveys in the United States have found about 40% of women overall experience problems in one of these areas, regardless of whether they are trying to conceive, with desire being the most common area of dissatisfaction.
Again, not all studies find this association, and not everyone experiences this; if you are just starting the process of trying to conceive, do not worry that it is paradoxically going to ruin your sex life. However, if this does ring true for you, then many of our fellow Psychology Today bloggers have resources for you. For starters, check out: Michael A. Castleman, Isadora Alman, Sari Cooper, Michael Shelton, Stephen Snyder, Pamela Madsen, and Kristen Mark.
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 Olson, D.H. & DeFrain, J. (1994). Marriage and the Family: Diversity and Strengths. Mountain View, CA. Mayfield.
 Call,V., Sprecher, S., & Schwartz, P.(1995)The Incidence and Frequency of marital Sex in a National Sample. Journal of marriage and the Family 57 (August 1995): 639-652.
Rothman, K.J., Wise, L.A., Sorensen, H.T., Riis, A.H., Mikkelson, E.M. and Hatch, E.E. Volational determinants and age-related decline in fecundabiliy: a general population cohort study in Denmark. Fertility and Sterility, 99:7 (1958-1964).
 Shifren, J.L., Monz, B.U., Russo, P.A., Segreti, A. and Johannes, C.B. (2008) Sexual Problems and Distress in United States Women. Obstetrics & Gynecology. 112: 5 (970-978).