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Contraception. 1987 Dec;36(6):641-50.

The effect of oral contraceptive pills on levels of oxytocin in plasma and on cognitive functions.

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Department of Obstetrics and Gynecology, Huddinge University Hospital, Stockholm, Sweden.


Millions of healthy women use combined oral contraceptives (o.c.) for decades. In spite of that, little is known about their possible effects on cognitive functions. In this open cross-over study, 20 women were examined twice at four-week intervals at a fixed period of the menstrual cycle when they were and when they were not taking o.c. They were examined with a test-battery to assess cognitive functions. Blood samples were taken before and after breakfast to assess levels of oxytocin and prolactin. A significant increase in levels of oxytocin was registered when the women were on o.c. There was no significant difference in performance on the psychometric tests when the participants were on o.c. compared to when they were without o.c.


20 health and normally menstruating women, ranging in age from 19-39, participated in this study designed to evaluate the influence of oral contraception (OC) on cognitive performance and the influence of OC on oxytocin levels in plasma and to correlate the levels of oxytocin to cognitive performance. Study participants were tested on 2 occasions at 4-week intervals. On 1 occasion, participants were tested in their luteal phase in a spontaneous menstrual cycle of approximately 28 days; on the other occasion, they were tested on the same cycle day when they were on OC. The participants served as their own controls, that is: 11 women were tested the 1st time in a spontaneous menstrual cycle, while the remaining 9 women performed their 1st test when they were on OC. All OCs used were of the combined estrogen-gestagen type with low hormonal content. When the series of blood sampling was completed, the psychometric testing started. Significantly higher levels of oxytocin in plasma were registered during OC treatment compared to no treatment. The levels o prolactin in serum was not affected by breakfast nor OC treatment. There was no significant effect of the test order to any psychometric test according to a 2-way analysis of variance. Thus, all the results were analyzed as a within-subject design. There were 5 psychometric variables in all. In all but 1, Student's 2-tailed t-tests, paired observations, have been used. In the 1 test, 2-way Anova was used. In the Associative Learning Test, there was a strong significant effect of treatment or interaction. In the remaining 4 psychometric tests, no significant differences were observed when the participants were taking OC compared to when they were without OC. There was no significant correlation between hormonal level of oxytocin or prolactin and performance on the psychometric tests. There also was no correlation between the indexes of change of the 2 hormones and the indexes of change of the psychometric tests.

[Indexed for MEDLINE]

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