Objectives: The aim of this study was to identify variations in nervous thresholds in different phases of the menstrual cycle in eumenorrheic women and users of oral contraceptives. Method: An observational study was performed including 56 volunteers, consisting of 30 eumenorrheic women who were non-users of oral contraceptives and 26 users of oral contraceptives. An electrical stimulator was employed to assess their nervous thresholds, with pulses applied at a fixed frequency of 2,500 Hz, modulated at 50 Hz, with phase variances of 20 ms, 50 ms and 100 ms. Sensitivity, motor and pain thresholds were evaluated during five menstrual cycle phases: phase 1 - menstrual, phase 2 - follicular, phase 3 - ovulatory, phase 4 - luteal and phase 5 - premenstrual. Results: The results indicated low sensitivity thresholds of 100 ms for non-users of oral contraceptives and 50 ms for oral contraceptive users in phase 5. Low motor thresholds of 20 ms, 50 ms and 100 ms were observed for nonusers of oral contraceptives in phase 5, while that of oral contraceptive users was 100 ms. Finally, a low pain threshold of 100 ms was observed in phase 5, but only in the oral contraceptive group. Conclusion: Nervous thresholds vary systematically across the phases of the menstrual cycle, with or without the use of oral contraceptives. These variations should be taken into account during research performed in women. © 2013 CLINICS.687901908Tommaso, M., Pain perception during menstrual cycle (2011) Curr Pain Headache Rep., 15 (5), pp. 400-406. , http://dx.doi.org/10.1007/s11916-011-0207-1Martin, V.T., Ovarian hormones and pain responses: A review of clinical and basic science studies (2009) Gend Med., 6 (SUPPL. 2), pp. 168-192. , http://dx.doi.org/10.1016/j.genm.2009.03.006Barbosa, M.B., Montebelo, M.I.L., Guirro, E.C.O., Determination of sensory perception and motor response thresholds in different phases of the menstrual cycle (2007) Braz J Phys Ther., 11, pp. 443-449Sherman, J.J., LeResche, L., Does experimental pain response vary across the menstrual cycle? A methodological review (2006) Am J Physiol Regul Integr Comp Physiol., 291 (2), pp. R245-R256. , http://dx.doi.org/10.1152/ajpregu.00920.2005Riley III, J.L., Robison, M.E., Wise, E.A., Price, D.D., A meta-analytic review of pain perception across the menstrual cycle (1999) Pain., 81 (3), pp. 225-235. , http://dx.doi.org/10.1016/S0304-3959(98)00258-9Wiesenfeld-Hallin, Z., Sex differences in pain perception (2005) Gend Med., 2 (3), pp. 137-145. , http://dx.doi.org/10.1016/S1550-8579(05)80042-7Bartley, E.J., Rhudy, J.L., Endogenous inhibition of the neciceptive flexion reflex (NFR) and pain ratings during the menstrual cycle in healthy women (2012) Ann Behav Med., 43 (3), pp. 343-351. , http://dx.doi.org/10.1007/s12160-012-9345-xRhudy, J.L., Bartley, E.J., The effect of the menstrual cycle on affective modulation of pain and nociception in healthy women (2010) Pain., 149 (2), pp. 365-372. , http://dx.doi.org/10.1016/j.pain.2010.02.041Creinin, M.D., Keverline, S., Meyn, L.A., How regular is regular? An analysis of menstrual cycle regularity (2004) Contraception., 70 (4), pp. 289-292. , http://dx.doi.org/10.1016/j.contraception.2004.04.012Moss, R.H., The development of a menstrual distress questionnaire (1968) Psychosom Med., 30 (6), pp. 853-867Amodei, N., Nelson-Gray, R.O., Reactions of dysmenorrheic and nondysmenorrheic women to experimentally induced pain throughout the menstrual cycle (1989) J Behav Med., 12 (4), pp. 373-385. , http://dx.doi.org/10.1007/BF00844930Lund, I., Lundeberg, T., Kowalski, J., Svensson, E., Gender differences in electrical pain threshold responses to transcutaneous electrical nerve stimulation (TENS) (1989) J Behav Med., 12 (4), pp. 373-385Férin, M., Jewelewiez, R., Warren, M., (1993) The menstrual cycle, , [dissertation], Oxford: University PressWalpurger, V., Pietrowsky, R., Kirschbaum, C., Effects of the menstrual cycle on auditory event-related potentials (2004) Horm Behav., 46 (5), pp. 600-606. , http://dx.doi.org/10.1016/j.yhbeh.2004.07.002Lamprecht, V.M., Grummer-Strawn, L., Development of new formulas to identify the fertile time of the menstrual cycle (1996) Contraception., 54 (6), pp. 339-343. , http://dx.doi.org/10.1016/S0010-7824(96)00202-8Arevalo, M., Sinai, I., Jennings, V., A fixed formula to define the fertile window of the menstrual cycle as the basis of simple method of natural family planning (1999) Contraception., 60 (6), pp. 357-360. , http://dx.doi.org/10.1016/S0010-7824(99)00106-7Fernández, G., Weis, S., Stoffel-Wagner, B., Tendolkar, I., Reuber, M., Beyenburg, S., Menstrual cycle-dependent neural plasticity in the adult human brain is hormone, task and region specific (2003) J Neurosci., 23 (9), pp. 3790-3795Straneva, P.A., Maixner, W., Pedersen, C.A., Costello, N.L., Girdler, S.S., Menstrual cycle, beta-endorphins, and pain sensitivity in premenstrual dysphoic disorder (2002) Health Psychol., 21 (4), pp. 358-367. , http://dx.doi.org/10.1037/0278-6133.21.4.358Tassorelli, C., Sandrini, G., Cecchini, A.P., Nappi, R.E., Sances, G., Martignoni, E., Changes in nociceptive flexion reflex threshold across the menstrual cycle in healthy women (2002) Psychosom Med., 64 (4), pp. 621-626. , http://dx.doi.org/10.1097/01.PSY.0000021945.35402.0DBajaj, P., Arendt-Nielsen, L., Bajaj, P., Madsen, H., Sensory changes during the ovulatory phase of the menstrual cycle in healthy women (2001) Eur J Pain., 5 (2), pp. 135-144Schultheiss, O.C., Dargel, A., Rohde, W., Implicit motives and gonadal steroid hormones: Effects of menstrual cycle phase, oral contraceptive use and relationship status (2003) Horm Behav., 43 (2), pp. 293-301. , http://dx.doi.org/10.1016/S0018-506X(03)00003-5Hampson, E., Kimura, D., Reciprocal effects of hormonal fluctuations on human motor and perceptual spatial skills (1988) Behav Neurosci., 102 (3), pp. 456-459. , http://dx.doi.org/10.1037/0735-7044.102.3.456Oshima, M., Ogawa, R., Menkes, D.L., Current perception threshold increases during pregnancy but does not change across menstrual cycle (2002) J Nippon Med Sch., 69 (1), pp. 19-23. , http://dx.doi.org/10.1272/jnms.69.19Smith, S.S., Female sex esteroid hormones: From receptors to networks to performance-actions on the sensorimotor system (1994) Prog Neurobiol., 44 (1), pp. 55-86. , http://dx.doi.org/10.1016/0301-0082(94)90057-4Edwards, H.E., Burnham, W.M., Mendonca, A., Bowlby, D.A., McLusky, N.J., Steroid hormones affect limbic afterdischarge thresholds and kindling rates in adult female rats (1999) Brain Res., 838 (1-2), pp. 136-150. , http://dx.doi.org/10.1016/S0006-8993(99)01619-4Abraham, S., Luscombe, G., Soo, I., Oral contraception and cyclic changes in premenstrual and menstrual experiences (2003) J Psychosom Obstet Gynaecol., 24 (3), pp. 185-193. , http://dx.doi.org/10.3109/01674820309039672Segal, M., Murphy, D., Estradiol induces formation of dendritic spines in hippocampal neurons: Functional correlates (2003) J Psychosom Obstet Gynaecol., 24 (3), pp. 185-193Woolley, C.S., Schwartzkroin, P.A., Hormonal effects on the brain (1998) Epilepsia., 39 (SUPPL. 8), pp. S2-S8. , http://dx.doi.org/10.1111/j.1528-1157.1998.tb02601.xMurphy, D.D., Segal, M., Regulation of dendritic spine density in cultured rat hippocampal neurons by steroid hormones (1996) J Neurosci., 16 (13), pp. 4059-4068Inghilleri, M., Conte, A., Curá, A., Frasca, V., Lorenzano, C., Berardelli, A., Ovarian hormones and cortical excitability. An rTMS study in humans (2004) Clin Neurophysiol., 115 (5), pp. 1063-1068. , http://dx.doi.org/10.1016/j.clinph.2003.12.003Li, H., Nakajima, S.T., Chen, J., Tood, H.E., Overstreet, J.W., Lasley, B.L., (2001) Difference in hormonal characteristics of contraceptive versus nonconceptive menstrual cycles., 75 (3), pp. 549-553Beatty, W.W., Gonadal hormones and sex differences in non-reproductive behaviors in rodents: Organizational and activational influences (1979) Horm Behav., 12 (2), pp. 112-163. , http://dx.doi.org/10.1016/0018-506X(79)90017-5Herren, R.Y., The effect of high and low female sex hormone concentration on the two-point threshold of pain and touch and upon tactile sensitivity (1933) J Exper Psychol., 16 (2), pp. 324-327Robinson, J.E., Short, R.V., Changes in breast sensitivity at puberty during the menstrual cycle, and at parturition (1977) Br Med J., 1 (6070), pp. 1188-1191. , http://dx.doi.org/10.1136/bmj.1.6070.1188Veith, J.L., Anderson, J., Slade, S.A., Thompson, P., Laugel, G.R., Getzlaf, S., (1984) Plasma b-endorphin, pain thresholds and anxiety levels across the human menstrual cycle., 32 (1), pp. 31-34Tedford, W.H., Warren, D.E., Flynn, W.E., Alteration of shock aversion thresholds during the menstrual cycle (1977) Percept Psychophys., 21 (2), pp. 193-196. , http://dx.doi.org/10.3758/BF03198725Young-Hee, B., Sun-Ju, K., Jae-Kap, C., Pain Threshold e taste threshold variation across the menstrual cycle (2001) Korean J Oral Med., 26, pp. 253-259Geng, B., Yoshida, K., Jensen, W., Impacts of selected stimulation patterns on the perception threshold in electrocutaneous stimulation (2011) J Neuroeng Rehabil., 8, p. 9. , http://dx.doi.org/10.1186/1743-0003-8-9Kantor, G., Alon, G., Ho, H.S., The effects of selected stimulus waveforms on pulse and phase characteristis at sensory and motor thresholds (1994) Phys Ther., 74 (10), pp. 951-962Giamberardino, M.A., Berkley, K.J., Iezzi, S., de Bigontina, P., Vecchiet, L., Pain threshold variations in somatic wall tissues as a function of menstrual cycle, segmental site an tissue depth in non-dysmenorrheic women, dysmenorrheic women and men (1997) Pain., 71 (2), pp. 187-197. , http://dx.doi.org/10.1016/S0304-3959(97)03362-9Dao, T.T.T., Knight, K., Ton-That, V., Modulation of myofascial pain by the reproductive hormones:A preliminary report (1998) J Prosthet Dent., 79 (6), pp. 663-670Silberstein, S.D., Migraine: Preventive treatment (2001) Curr Med Res Opin., 17 (SUPPL. 1), pp. s87-s93. , http://dx.doi.org/10.1185/0300799039117007Isselée, H., de Laat, A., Bogaerts, K., Lysens, R., Long-term fluctuations of pressure pain thresholds in healthy men, normally menstruating women and oral contraceptive users (2001) Eur J Pain., 5 (1), pp. 27-37Dennerstein, L., Spencer-Gardner, C., Gotts, G., Brown, J.B., Smith, M.A., Burrows, G.D., Progesterone and the premenstrual syndrome: A double blind crossover trial (1985) Br Med J (Clin Res Ed)., 290 (6482), pp. 1617-1621. , http://dx.doi.org/10.1136/bmj.290.6482.1617Teepker, M., Peters, M., Kundermann, B., Vedder, H., Schepelmann, K., Lautenbacher, S., The effects of contraceptives on detection and pain thresholds as well as headache intensity during menstrual cycle in migraine (2011) Headache., 51 (1), pp. 92-104. , http://dx.doi.org/10.1111/j.1526-4610.2010.01775.xOelkers, W.K., Effects of estrogens and progestens on the renninaldosterone system and blood pressure (1996) Steroids., 61 (4), pp. 166-171. , http://dx.doi.org/10.1016/0039-128X(96)00007-4