Penelitian ini bertujuan untuk mengetahui perbedaan status hidrasi, perubahan nilai total serum bilirubin, dan perbedaan durasi fototerapi bayi yang mendapat fototerapi dengan diberi ASI dan susu formula Desain penelitian yang digunakan adalah deskriptif, observasional, dan prospektif terhadap 34 bayi cukup bulan yang sehat di sebuah rumah sakit di Jakarta. Responden dibagi ke dalam tiga kelompok, yaitu; kelompok bayi yang hanya diberi susu formula, kelompok bayi yang hanya diberi ASI, dan kelompok bayi yang diberi ASI dan susu formula. Hasil penelitian, menggunakan analisa data univariat dan bivariat dengan tes statistik Chi-square, ANOVA dan Mann-Whitney, menunjukkan bahwa tidak ada perbedaan status hidrasi dan perbedaan perubahan nilai total serum bilirubin (p= 0,76; α= 0,05), tetapi ada perbedaan durasi fototerapi antara ke tiga kelompok (p= 0,001; α= 0,05). Kelompok yang diberi ASI mempunyai durasi fototerapi tersingkat. Penelitian ini merekomendasikan agar perawat memastikan keefektifan breastfeeding selama fototerapi.

---

This study aims to determine differences in hydration status, changes in value of total serum bilirubin, and the difference induration of phototherapy newborns who received phototherapy with breast-fed and formula feeding. The study design used is descriptive, observational, and prospective to 34 healthy newborns at a hospital in Jakarta. Respondents were divided in to three groups, there is group of newborns with formula feeding, group of newborns with breast-fed, and group of newborns with breast -fed and formula feeding. The results, using univariate and bivariate data analysis with statistical chi-square test,ANOVA, and Mann-Whitney, shows that there is no difference in hydration status and differences in changes in value of total serum bilirubin (p= 0.76; α= 0.05) , but there are differences in the duration of phototherapy between to the three groups (p=0.001; α= 0.05). The group who were breastfeed has the shortest duration of phototherapy. This study recommends that nurses ensure the effectiveness of breastfeeding during phototherapy.