Effects of 660-nm Photobiomodulation Therapy on Pain and Healing of Nipple Trauma in Lactating Women: A Pilot Randomized Double-Blind Controlled Trial

Technical Summary: Effects of 660-nm Photobiomodulation Therapy on Nipple Trauma in Lactating Women

Problem Statement
Nipple trauma, manifesting as fissures, erosions, or excoriations, is a prevalent complication in lactating women, often resulting from incorrect infant latching or improper breast pump use. These injuries disrupt cutaneous integrity, causing significant pain and increasing the risk of secondary complications such as puerperal mastitis and breast abscesses due to bacterial colonization. The resulting maternal distress frequently leads to premature weaning. While Photobiomodulation Therapy (PBMT) has emerged as a non-invasive adjuvant for wound healing—utilizing red spectrum lasers (λ = 660 nm) to stimulate mitochondrial ATP synthesis, accelerate metabolism, and promote tissue repair—clinical application is hindered by a lack of standardized protocols. Specifically, there is a consensus gap regarding precise dosimetry, optimal session frequency, and a scarcity of well-designed, sham-controlled trials to validate efficacy during lactation.

Methodology
This study was a prospective, randomized, double-blind, controlled pilot trial conducted at reference centers in Diamantina, Minas Gerais, Brazil.

• Participants: The final sample consisted of 20 postpartum women (n=10 per group) with clinical nipple trauma, recruited via convenience sampling. The study was designed as an exploratory pilot with 80% statistical power to detect a large effect size (Cohen's d ≈ 1.25), rather than the 95% power originally calculated for a larger sample.
• Groups: Participants were randomly allocated to:
  • PBMT Group: Standard clinical care (latch guidance, positioning, moist wound healing with breast milk) + Active PBMT.
  • Placebo Group: Standard clinical care + Sham PBMT.
• Intervention Protocol: Interventions occurred up to seven times over 15 days (3 times/week). PBMT was administered using an InGaAlP laser (660 nm) in contact mode.
  • Parameters: 40 mW power, 10 J/cm² energy density, 0.4 W/cm² irradiance.
  • Application: 10 seconds per point on five specific locations (one central point over the lesion, four peripheral points on the areola spaced 2 cm apart). Total exposure: 50 seconds per session.
  • Blinding: Double-blinding was maintained using visually identical Twin Flex® devices; the placebo device had light emission blocked internally but emitted identical acoustic and visual signals.
• Outcome Measures:
  • Primary: Pain intensity (Visual Analogue Scale, VAS 0–10) and breastfeeding quality (LATCH Scale).
  • Secondary: Lesion severity (Nipple Trauma Score, NTS 0–5) and lesion area quantification via photogrammetry and pixel counting.
• Statistical Analysis: Data were analyzed using Mixed-Effects Models for longitudinal variables (pain, lesion area), Two-Way ANOVA for trauma progression, and Wilcoxon/Mann-Whitney tests for other comparisons (significance level p < 0.05).

Key Results

• Pain Reduction: The PBMT group demonstrated a statistically significant reduction in pain scores starting from the third session (p = 0.0174) compared to the Placebo group. By the seventh session, the PBMT group achieved total analgesia (mean VAS = 0.000), whereas the Placebo group continued to report residual pain (p = 0.0006).
• Tissue Repair: PBMT significantly accelerated tissue repair. The PBMT group reached complete lesion regression (NTS = 0) by the end of the study, while the Placebo group maintained residual trauma (NTS = 1). Significant differences in healing progression were observed from the third session onward.
• Breastfeeding Quality: Both groups showed improvement in LATCH scores post-intervention. The PBMT group achieved superior post-intervention scores compared to the Placebo group, though the authors note that baseline imbalances (lower initial scores in the PBMT group) may have influenced the magnitude of this change.
• Demographics: The sample was homogeneous regarding obstetric history, with 90% of participants in both groups presenting with bilateral nipple involvement. The most common lesion type was excoriation.

Significance and Claims
The paper concludes that combining PBMT (λ = 660 nm) with standard clinical management is effective for pain relief, accelerating tissue repair, and improving breastfeeding quality in women with nipple trauma. The authors position PBMT as a promising adjuvant resource that can prevent complications and support the maintenance of exclusive breastfeeding.

The study acknowledges its limitations, specifically its nature as a pilot trial with a small sample size (N=20) and the lack of a priori power calculation for the final sample. However, the authors assert that the results elucidate the benefits of specific PBMT parameters (660 nm, 10 J/cm², 7 sessions) and support the development of more standardized, evidence-based clinical protocols for managing nipple fissures. The integration of this technology into postpartum care is presented as a potential advancement for maternal and child public health by fostering prolonged breastfeeding.