Neonates undergo several painful procedures and these pain experiences can alter clinical outcome and behavior. The investigators aim to investigate the analgesic effect of low level laser for procedural pain during heel lancing of term neonates.

This open-label, randomized controlled trial involves 130 term newborn infants (gestational ages between 37 weeks to 42 weeks) who need heel lancing for newborn screening. Subjects are randomly assigned to low level laser group or breast milk group. Subjects in breast milk group are given 5ml expressed breast milk by mouth using a syringe tube inserted to the participant's oral cavity over a 2-minute period. LaserPen is applied to the local point for 20 seconds where heel-lancing will be performed in the low level laser group. Then heel lancing is performed and two observers who are blinded to the intervention record the physiological (heart rate and oxygen saturation) and behavioral parameters (duration of crying and modified neonatal facial coding scores) following the procedure. Heart rate variation of participants is record by CheckMyHeart ECG monitor. The salivary swab method is used to detect the infant's salivary cortisol and amylase level as biomarker for stress evaluation. During the study course, digital cameras continuously record participants' behavior. Independent t-test, chi-squared test and one way ANOVA are used for statistical analysis.

Inclusion Criteria:

• healthy fullterm neonates (37-42 gestational age)
• Apgar score >= 7
• will receive newborn screening

Exclusion Criteria:

• >42 or < 37 gestational age
• perinatal asphyxia
• major malformations or any other disease that need intensive care
• drug withdrawal received previous treatment

Two independent assessors blinded to intervention read the video, and then record vital signs and pain score. The videos are cut from heel-lancing to the end so that the assessors do not know whether the neonate receive low level laser or breast milk.