Reference birthweight range for multiple birth neonates in Japan

Table 2 gestational age and birthweight of twins according to variables

gestational age	no. of cases	mean (weeks)	standard deviation (weeks)	significance of difference
total	64464	37.2	2.7
male	32211	37.2	2.6	***
female	32253	37.3	2.6
primipara	29106	37.1	2.8	***
multipara	35358	37.3	2.6
like-sexed male	25510	37.1	2.7	***
like-sexed female	25552	37.3	2.7
unlike-sexed	13402	37.4	2.6
birthweight	no. of cases	mean (kg)	standard deviation (kg)
total	64447	2.39	0.51
male	32202	2.43	0.51	***
female	32245	2.36	0.50
primipara	29098	2.31	0.50	***
multipara	35349	2.46	0.50
1st twins	32156	2.42	0.50	***
2nd twins	32153	2.36	0.51
like-sexed male	25501	2.41	0.52	***
like-sexed female	25545	2.35	0.50
unlike-sexed male	6701	2.49	0.50
unlike-sexed female	6700	2.39	0.48

ISSN: 1471-2393