Abstract 1171 Poster Session II, Sunday, 5/2 (poster 34)

Objective: verify possible gender differences in pain expression in preterm and term newborn infants.

Patients and Method: 65 neonates with 28-42w gestational age that required a capillary puncture were studied: healthy term neonates for PKU screening and clinically stable premature infants for hypoglycemia screening. Patients were divided in 2 groups according to gender:

  • Female: n=37, BW 2.5±0.8 wk, 5 min. Apgar 9±1, 41±13 h of life, 34±7 min. after feeding

  • Male: n=28, BW 2.6±0.9 kg, 36±3 wk, 5min. Apgar 9±1, 41±13 h of life, 34±7 min. after feeding

The Neonatal Facial Coding System (NFCS: 0-8 points; Granau & Craig, 1987) and the Neonatal Infant Pain Scale (NIPS: 0-7 points; Lawrence et al, 1993) were evaluated at bedside prior to the puncture, when patients were at rest; during foot heating; during capillary puncture; and at 1, 3, and 5 minutes after puncture.

Results: Table shows pain scales scores at the 6 study periods in both groups of infants. Data were analyzed by ANOVA. Regarding the NFCS, a significant difference for the main effect time (F5;295 = 127.02; p<0.000001), and an interaction between gender and time (F5;295 = 12.616; p=0.025) were noted. Female newborn infants had higher NFCS scores during puncture and 1 minute afterwards, compared to male neonates (Bonferroni's comparison method: p<0.05). When patients were divided in 3 groups according to gestational age (<34, 34-37.9, ≥ 38 weeks), differences in pain expression between female and male infants persisted. Regarding NIPS, ANOVA showed only a significant difference among the mean NIPS scores during that 6 study periods for the whole group of neonates (F5;295 = 131.68; p<0.000001).

Table 1 No caption
Full size table

Conclusion: recently born female neonates of all gestational ages expressed more facial features of pain compared to their male counterparts during the capillary puncture and one minute afterwards. Differences in pain processing and/or in pain expression among genders could explain this finding.