The purpose of this study is tu assess the influence of oral contraceptives (OC) on diffuse noxious inhibitory control (DNIC) in healthy women, tested during high, low endogenous estrogens sessions and ovulatory period.

After being informed about the study and it protocol, all patients giving written informed consent, will undergo to a cephalic (masseter) and extracephalic (finger) mechanical stimulus to evaluate the threshold of mechanical pain, and physiological records of systolic/diastolic pressure and heart rates. After, we will evaluate the threshold response and physiological rates to the same mechanical stimulus under a thermal (cold) conditional pain (TCP) at 3 different moments of menstrual period in No contraceptive group (No OC) versus Contraceptive group (CO). Finally, we will compare the mechanical threshold response, physiological rates and pain perception between both groups.

Inclusion Criteria:

• Healthy women with oral contraceptive treatment (for at least 3 consecutive months), greater than or equal to 15 years old.
• Healthy women without oral contraceptive treatment, greater than or equal to 15 years old.
• Non pregnant women.
• Not under convulsive, chronic pain, antidepresive, antihypertensive, pharmacological treatments
• Without systemic pathologies.

Exclusion Criteria:

• Treatment of a pain, depression, hypertension, convulsion condition with or without medication.
• Regular use of benzodiazepines.
• Systemic pathologies
• Pregnant women
• Menopausal women