The researcher responsible for the photobiomodulation application will simulate irradiation by positioning the device in the exact location as in the Photobiomodulation Group; however, the equipment will remain turned off.

To prevent participants from identifying the group to which they belong, the device's activation sound (beep) will be pre-recorded and played during the application.

VAS (Visual Analog Scale):

Pain intensity was assessed using the Visual Analog Scale (VAS), a validated tool consisting of a 10-centimeter horizontal line ranging from 0 (no pain) to 10 (worst possible pain). Participants were instructed to mark a point on the line that best represented their perceived pain at each procedural step:

Hysterometry: A sterile uterine sound is inserted to assess the direction and depth of the uterine cavity, which is essential for guiding correct IUD placement and minimizing complications.

VAS (Visual Analog Scale):

Pain intensity was assessed using the Visual Analog Scale (VAS), a validated tool consisting of a 10-centimeter horizontal line ranging from 0 (no pain) to 10 (worst possible pain). Participants were instructed to mark a point on the line that best represented their perceived pain at each procedural step:

Intrauterine Device Insertion: The IUD is carefully introduced through the cervical canal and positioned at the uterine fundus. Once released, the device remains in place, and the strings are trimmed to ensure proper follow-up and future removal.

VAS (Visual Analog Scale):

Pain intensity was assessed using the Visual Analog Scale (VAS), a validated tool consisting of a 10-centimeter horizontal line ranging from 0 (no pain) to 10 (worst possible pain). Participants were instructed to mark a point on the line that best represented their perceived pain at each procedural step.

VAS (Visual Analog Scale):

Pain intensity was assessed using the Visual Analog Scale (VAS), a validated tool consisting of a 10-centimeter horizontal line ranging from 0 (no pain) to 10 (worst possible pain). Participants were instructed to mark a point on the line that best represented their perceived pain at each procedural step.

VAS (Visual Analog Scale):

Pain intensity was assessed using the Visual Analog Scale (VAS), a validated tool consisting of a 10-centimeter horizontal line ranging from 0 (no pain) to 10 (worst possible pain). Participants were instructed to mark a point on the line that best represented their perceived pain at each procedural step.

Paracetamol intake was recorded at the T 380 copper IUD insertion baseline. At the beginning of the study, each participant will receive a blister pack of paracetamol (a pure analgesic) (Jóźwiak-Bebenista, 2014), which must be kept until the end of the study and will only be used in cases of pain. At the end of the study, the remaining number of tablets will be assessed as an additional pain measurement parameter. The analgesic used will be paracetamol 500 mg, to be taken only if necessary at a dose of one tablet every six hours. Participants will be asked to record in writing the number of tablets taken, along with the date and time of consumption. A monitoring procedure will be implemented to ensure adherence: participants must bring their blister pack to follow-up visits for verification.

Paracetamol intake was recorded from baseline to 24 hours after the T 380 copper IUD insertion. At the beginning of the study, each participant will receive a blister pack of paracetamol (a pure analgesic), which must be kept until the end of the study and will only be used in pain cases. At the end of the study, the remaining number of tablets will be assessed as an additional pain measurement parameter. The analgesic used will be paracetamol 500 mg, to be taken only if necessary, at a dose of one tablet every six hours. Participants will be asked to record in writing the number of tablets taken, along with the date and time of consumption. A monitoring procedure will be implemented to ensure adherence: participants must bring their blister pack to follow-up visits for verification. Medication use will be tracked from baseline to 24 hours post-insertion.

Generalized anxiety symptoms were evaluated at baseline in patients using the T 380 copper intrauterine device for contraception, through the Generalized Anxiety Disorder 7-item (GAD-7) questionnaire. This self-administered tool, based on DSM-IV criteria, assesses the frequency of anxiety symptoms over the prior two weeks using a four-point Likert scale: 0 (never), 1 (several days), 2 (more than half the days), and 3 (nearly every day). Suitable for clinical and research use, and applicable in person or digitally, it takes about five minutes to complete. Total scores range from 0 to 21, with higher scores indicating more severe symptoms, categorized as follows: 0-4 (no anxiety), 5-9 (mild), 10-14 (moderate), and 15-21 (severe anxiety).

Generalized anxiety symptoms were evaluated at baseline in patients using the T 380 copper intrauterine device for contraception, through the Generalized Anxiety Disorder 7-item (GAD-7) questionnaire. This self-administered tool, based on DSM-IV criteria, assesses the frequency of anxiety symptoms over the prior two weeks using a four-point Likert scale: 0 (never), 1 (several days), 2 (more than half the days), and 3 (nearly every day). Suitable for clinical and research use, and applicable in person or digitally, it takes about five minutes to complete. Total scores range from 0 to 21, with higher scores indicating more severe symptoms, categorized as follows: 0-4 (no anxiety), 5-9 (mild), 10-14 (moderate), and 15-21 (severe anxiety).

Measured using the WHOQOL-Pain instrument at Baseline. The WHOQOL-Pain is an additional module of the WHOQOL-100, specifically developed to assess quality of life in individuals experiencing chronic pain. Each facet consists of four questions addressing different dimensions of the pain experience. Responses follow a five-point Likert scale, measuring intensity, capacity, evaluation, and frequency. Scores are converted to a 0 to 100 scale, allowing for a quantitative interpretation of pain levels and their impact on quality of life. The WHOQOL-Pain items are not integrated into the WHOQOL-100 and are applied separately at the end of the main questionnaire. This structure facilitates individualized analysis of pain-related facets, enabling a specific and detailed evaluation of physical chronic pain experiences.

Measured using the WHOQOL-Pain instrument from baseline to 48 hours after insertion. The WHOQOL-Pain is an additional module of the WHOQOL-100, specifically developed to assess quality of life in individuals experiencing chronic pain. Each facet consists of four questions addressing different dimensions of the pain experience. Responses follow a five-point Likert scale, measuring intensity, capacity, evaluation, and frequency. Scores are converted to a 0 to 100 scale, allowing for a quantitative interpretation of pain levels and their impact on quality of life. The WHOQOL-Pain items are not integrated into the WHOQOL-100 and are applied separately at the end of the main questionnaire. This structure facilitates individualized analysis of pain-related facets, enabling a specific and detailed evaluation of physical chronic pain experiences.

Patient satisfaction with T 380 copper intrauterine device insertion for contraceptive purposes was assessed 15 minutes after the procedure using a dichotomous questionnaire adapted from Lopes et al. (2015). The instrument included three yes-or-no questions: (1) Was the insertion experience pleasant? (2) Would you undergo the procedure again in the future? (3) Would you recommend it to a friend? For each item, the response "yes" indicated satisfaction with the procedure, while "no" reflected dissatisfaction. Responses were scored as 1 for "yes" and 0 for "no", resulting in a total score ranging from 0 (maximum satisfaction) to 3 (maximum dissatisfaction). Higher scores indicated greater dissatisfaction with the procedure.

The time required to relieve abdominal discomfort (menstrual cramps) was recorded from the day of the baseline assessment.

The time required to relieve abdominal discomfort (menstrual cramps) was recorded until the day the discomfort stopped. The patient will be asked after 48 h

If IUD insertion fails, it will be assessed dichotomously (success/failure) from baseline to 24 hours after insertion, and verified by ultrasonography when necessary.

Including uterine perforation, IUD displacement, abdominal pain, increased vaginal bleeding, and allergic reactions. An open-ended question will allow participants to report adverse effects, followed by a list of potential effects to help recall any unreported symptoms.

Including cramps, mild pain, light bleeding, and tongue numbness. An open-ended question will be asked first, followed by a list of potential side effects for better recall.