Gestational age-specific normal birth weight for Japanese twins. Risk of early neonatal death in small-for-gestational-age and large-for-gestational-age twins.

OBJECTIVE: To construct nomograms for birth weight in Japanese twins and to investigate the risk of early neonatal death (death within seven days of birth) in small-for-gestational-age (SGA) and large-forgestational-age (LGA) twins as compared with appropriate-for-gestational-age (AGA) twins. STUDY DESIGN: Of 89,253 infants born at ≥24 weeks of gestation to women with multifetal pregnancies (96% twins) between 1989 and 1993 in Japan, 1,804 were stillborn, and 891 died within seven days of birth (early neonatal death [END] group). The remaining 86,558 infants were defined as the normal group. We constructed growth curves for the normal and END groups and compared the incidence of early neonatal death among the SGA, AGA and LGA infants. RESULTS: Birth weights in the END group were similar to those in the normal group until 33 weeks of gestation, but was lower than the birth weights of the normal group after 33 weeks. Both SGA and LGA infants had an increased risk of death within 7 days of birth as compared with AGA infants throughout gestation. CONCLUSION: Both SGA and LGA twins were at increased risk of death as compared with AGA twins. We recommend the use of birth weight nomograms in the management of twin pregnancies.