Trial construction of birthweight and birth length references for multiple birth neonates in Japan.

在日本，出生、死亡和死产证明目前存储在磁带上的数据文件中。这些证书在市卫生厅存档，并在日本厚生劳动省被更改为计算机档案。这个数据库包括性别、出生体重、胎龄、胎次、父亲和母亲的年龄。多胞胎的出生年龄按出生地、父母的年龄、胎龄和出生年份和月份确定；经产母亲的双胞胎出生体重高于初产母亲的双胞胎。本研究结果可用于日本多胞胎新生儿出生体重的估算，双胞胎出生身长中位数最大，三胞胎最小，四胞胎最小，双胞胎出生身长低于单胞胎，但小于双胞胎和单胞胎的出生体重。多胞胎新生儿表现出不对称的生长。围产期死亡率按体重和胎龄类别进行比较，双胞胎和三胞胎与单胞胎相比，在每个多胞胎内以最低的死亡率与所有其他风险±95%的相对危险度进行比较。出生体重和胎龄在多个特定的理想范围内，围产儿死亡率可降低90%以上。为了确定不和谐双胞胎的分界点，并澄清围产期死亡是由不和谐或低出生体重本身造成的，我们分析了双胞胎数据集。日本双胞胎的围产儿死亡率高于出生体重不超过20%的双胞胎。出生体重过低和出生体重过低对日本双胞胎的围产儿死亡率有显著影响。

In Japan, birth, death, and stillbirth certificates are currently stored in data files on magnetic tapes. These certificates are filed in the city health department and changed into computerized files in Ministry of Health, Labour and Welfare of Japan. This database contains sex, birthweight, gestational age, parity, ages of father and mother.Pairs of multiple births were identified by birthplace, the ages of the parents, gestational age, and the year and month of birth; The birthweight of twins from multiparous mothers was greater than those from primiparous mothers. Our results can be used for assessment of birthweight of multiple births in Japan.The median birth length according to gestational age was found to be the greatest in twins, lower in triplets and the lowest in quadruplets, Birth length of twins was shorter than singletons, but difference was smaller than that of birthweight between twins and singletons. Multiple birth neonates showed asymmetrical growth.Perinatal mortality was compared by categories of bithweight and gestational age, for twins and triplets versus singletons, and within each plurality by the lowest rate compared to all other rates as relative risks ±95% CIs. Perinatal death rates can be reduced by more than 90% with attainment of birthweight and gestational age a within a plurality-specific ideal range.To determine cut-off point for discordant twins, and to clarify whether perinatal deaths are caused by discordancy or low birth weight itself, twin dataset was analized. Perinatal mortality rate was higher than that among discordancy less than 20%.Perinatal death of Japanese twins was significantly affected by both discordancy and low birth weight.