Material and Method: A retrospective study was performed in Thai singleton pregnant women with confirmed gestational age between 24 and 42 weeks (168-294 days), delivered at Rajavithi Hospital. Birthweights were graphed as 5th, 10th, 50th, and 90th percentile, and classified in gestational age as male, female, and both sexes.

Results: In all 7,506 neonates: 3,973 male and 3,533 female, were included during the 4-year study period. The standard intrauterine growth curves at 5th, 10th, 50th, and 90th percentile in male neonates were higher in value but similar in shape than those in female neonates.

Conclusion: Male birthweights were higher but similar in shape compared with those of female in all gestational ages (24-42 weeks).

Keywords: Thai neonate, Intrauterine, Birthweight, Growth curve, Rajavithi Hospital (RH)