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Crawford, Natalie M.; Pritchard, David A.; Herring, Amy H.; & Steiner, Anne Z. (2016). Prospective Evaluation of the Impact of Intermenstrual Bleeding on Natural Fertility. Fertility and Sterility, 105(5), 1294-1300. PMCID: PMC4853238


OBJECTIVE: To evaluate the impact of an episode of intermenstrual bleeding on the probability of conception in a menstrual cycle (fecundability). DESIGN: Prospective, time-to-pregnancy cohort study.
SETTING: Community-based cohort.
PATIENT(S): Women trying to conceive, ages 30 to 44 years, without known infertility.
INTERVENTION(S): Not applicable.
MAIN OUTCOME MEASURE(S): Current cycle and subsequent cycle fecundability.
RESULT(S): A total of 549 women provided 1,552 complete cycles for analysis. Intermenstrual and luteal bleeding were reported in 36% and 34% of cycles, respectively. Ninety-three percent of all intermenstrual bleeding was luteal. Cycles in which women had intermenstrual bleeding or luteal bleeding were statistically significantly less likely to result in conception (fecundability ratio [FR] 0.23; 95% confidence interval [CI], 0.16-0.34; and FR 0.22; 95% CI, 0.14-0.33). Women with an episode of intermenstrual and luteal bleeding had a statistically significant increase in the probability of pregnancy in the subsequent cycle (FR 1.61; 95% CI, 1.15-2.25; and FR 2.01; 95% CI, 1.52-2.87, respectively).
CONCLUSION(S): Intermenstrual bleeding statistically significantly decreases the odds of conceiving in that cycle but does not appear to negatively impact a woman's immediate future reproductive potential.


Reference Type

Journal Article

Year Published


Journal Title

Fertility and Sterility


Crawford, Natalie M.
Pritchard, David A.
Herring, Amy H.
Steiner, Anne Z.