This prospective interventional case control study was carried out in the Department of Paediatrics and Post natal ward of Obstetrics and Gynaecology, associated Gandhi Memorial Hospital over a period of one year from July 2010 to June 2011. The inclusion criteria were vaginally delivered, breastfeed, full term newborns with mean age of 40 hours and weight ranged from 2.59 to 2.732 kg. Exclusion criteria were sick newborn, formula fed, and those newborn whose mother received general anaesthesia and opiods during delivery. Informed and written consent was taken from parent/guardian and ethical committee approval was obtained before starting the study.

For sample size calculation we did a pilot study on 20 newborns and was found that mean PIPP score was 11 after giving 1 mL of 25% oral sucrose. So on assuming that there is 15% decline in mean PIPP score in breast feeding group, with power of study 90% and with alpha error of 0.05, a sample size of 51 newborns was required.

Recruited newborns were divided into control (group I) and intervention groups (group II and group III). Newborns were vaccinated on mother’s lap without any intervention in group I. A 1 mL of 25% oral sucrose was given two minutes prior to vaccination in group II. Breast feeding was started two minutes prior to vaccination and continued till the end of injection in group III.

Newborns were attached with BPL ACCURA MPM5553 multipara monitor using a neonatal probe. One lady attendant/Staff nurse along with mother was present when breast feed newborns were vaccinated. With all aseptic precautions, 0.5 mL hepatitis B vaccine was administered intramuscularly on anterolateral aspect of mid thigh to all neonates by auto disposable syringe. Position of baby (mother lap), the vaccinator, brand of vaccine and syringe used was the same throughout the study. Two observers were present during vaccination session, one for recording of facial expression of baby, and second observer was recording heart rate and oxygen saturation. Sucrose was administered in the absence of the observers and within two minutes, the intervention was done.

Gestational age was calculated by new Ballard score and behavioural state of newborns was assessed 15 seconds prior to vaccination, along with baseline recording of Heart Rate (HR) and SpO₂. The maximum HR and minimum oxygen saturation were noted between 0-30 seconds. Cry time was defined as the total duration of audible cry, and calculated by using the video time bar at 30 seconds, 60 seconds and 90 seconds and 120 seconds after vaccinations. The facial expression component of PIPP score was analysed by recording, the first 30 seconds of clipping by third observer. The primary outcome of the study was the PIPP score. It is a validated pain measure that includes contextual (behavioural state and gestational age), behavioural (brow bulging, eye squeezing and nasolabial furrowing) and physiological (heart rate and oxygen saturation) indicators of pain. Each indicator is scored in a 4 point scale (0-3) and total scores vary from 18 to 21 depending on the infant’s gestational age. In mild to moderate grade pain total score would be 6 to 12 and scores more than 12 indicates moderate to severe pain in newborns [21,22].

All data were entered into excel sheet and analysed by using SPSS version 16. PIPP score were compared by using ANOVA test, student’s t-test was used to compare continuous variables and two tailed Fisher-exact test or Chi-square test was used to compare categorical variables. The critical levels of significance of the results were considered at 0.05 levels i.e., p<0.05 was considered significant.

Out of 150 newborns, 74 were males and 76 were females. The neonatal characteristics like, mean birth weight, length, head circumference, mean age of vaccination and baseline heart rate and oxygen saturation were comparable between the groups [Table/Fig-1]. Mean PIPP scores were lower in group III (8.36) than in group II (11.06) and difference was significant (p<0.0001) The pain profile of newborns ranged from 9 to 18 with mean of 14.26 in group I, from 5 to 12 with mean of 11.06 in group II and from 1 to 12 with mean of 8.36 in group III respectively [Table/Fig-2]. Total duration of cry was lower in group III (23.8 sec) than group II (26.36 sec) and difference was not significant (p>0.05). The mean of heart rates were 13.47, 16.58 and 27.35 respectively in group III, group II and group I [Table/Fig-1]. The mean difference of increasing heart rate between group I and group II was 10.76, and between group I and group III was 13.88, and between group II and group III was 3.11 respectively. The difference was significant when compared with group I, II and III (p 0.001) and it was not significant between group III and group II (p 0.526) [Table/Fig-3].

The mean of oxygen saturation were 2.33, 2.07 and 4.19 respectively in group III, group II and group I [Table/Fig-1]. Difference in means of oxygen saturation between group I and group II was 2.11, between group I and group III was 1.86 and group II and group III was -0.25 respectively. The difference was significant when compared with group I (p 0.01) and it was not significant between group III and group II (p=1) [Table/Fig-3]. Minimum level of desaturation was observed in group II.

The observations of this study were, intramuscular injection produced moderate to severe pain response, breast feeding has superior analgesic effect than oral sucrose and physiological parameters (HR, SpO₂) and duration of cry were significantly lower in group II, and group III than group I, change in physiological parameters were not significant in group II and group III.

Analgesic effect of skin to skin contact, non nutritive sucking, kangaroo mother care, 24% oral sucrose, and 25-30% oral glucose were done in past by different researchers on pain induced by intramuscular injection in first 48 hours of life. The results are compiled in [Table/Fig-4]. Most of the studies mentioned in the table investigated the analgesic effect of skin to skin contact, and oral sucrose or glucose and found that skin to skin contact was superior to 25% glucose in reducing NFCS and NIPS (p=0.045) and NIPS score was lower in 30% glucose than water (p=0.001). A study by Moddares M et al., found that DAN score was lower in breastfeeding than control (p<0.001) [17]. None of the studies described the pain profile and comparison between analgesic effect of breast feeding and oral sucrose. In the present study, it was found that pain intensity was mild to moderate in group II and III that means breast feeding or oral sucrose alone is not able to bring down the pain score below non treatable levels. There was equal effect shown by breast feeding and sucrose on increase in heart rate and decrease in oxygen saturation similar results were found by other researchers mentioned in [Table/Fig-4] [12-17,23,24]. Author had assumed that 15% lower score in group III than group II during pilot study in 20 newborns for sample size calculation, but this difference was 25%.

The limitation of present study was lack of blinding because in breastfeeding group it is not possible to blind. Four or more investigators were blinded for pharmacological intervention; intervention was given by first investigator alone and then other investigators entered the immunization room, one administered vaccine after calling aloud in when the needle was inserted and when the needle was removed. Other investigator recorded all events on a digital camera from the removal of the needle, and fourth investigator analysed the outcome variable from the recording. Following this protocol three investigators were blinded to the pharmacological intervention. We could not study the role of the different component of breast feeding or the mechanism behind the analgesic effect of sucrose. The strength of study was use of PIPP score to assess pain because scale is validated and proven to discriminate painful from non painful stimuli, and we compared the analgesic effect of breast feeding and oral sucrose on pain response induced by intramuscular injection within 48 hours of life.

Intramuscular injection produces moderate to severe pain response in newborns, and breast feeding provides superior analgesia to oral sucrose and reduces moderate to severe painful response to mild to moderate grade in term newborns.