The Relationship Between the Menstrual Cycle, Oral Contraceptives, and Executive Function – Inhibition, Updating, and Shifting

Abstract: Previous research suggests a link between oral contraceptives and cognitive functioning in women, yet the results are contradictory and limited by methodological inconsistencies. This is the first meta-analysis of studies comparing naturally cycling women with women taking oral contraceptives on measures testing three executive functions: inhibition, updating, and shifting. We conducted a systematic literature search. Sixteen articles were included which were either cross-sectional or experimental and compared executive functions between women taking oral contraceptives ( n = 588) or cycling naturally ( n = 594). The average sample size was n = 32.33 for oral contraceptives users and n = 31.34 for naturally cycling women with ranges going from 8 to 144 participants per study. The age range of participants in all the studies taken together was between 18 for the youngest participant and 50 years old for the oldest participant with a mean age of M = 21.97, SD = 2.28. The studies presented a mixture of androgenic and anti-androgenic oral contraceptives which were rarely analyzed as separate groups. We ran a multivariate meta-analysis model to estimate the effect size of 66 comparisons in executive functioning between the groups taking oral contraceptives and the groups of naturally cycling women. Overall, the effect size of differences in executive functioning between groups was not significant: d = 0.044, SE = 0.0713, 95% CI [−0.0959, 0.1839], z = 0.62; p = 0.54. The analysis of the cycle phases and types of executive functions as moderators was not significant, however, the studies assessed as having a lower quality increased the overall effect. Our analysis indicates no difference between oral contraceptive users and naturally cycling women on core executive functions but the high amount of heterogeneity might reflect a high level of methodological diversity. Implications for research design and methodology are discussed.