Effects of Maternal Factors on Birth Weight in Japan

Table 1

Comparison of the perinatal/obstetrical variables between 2006 and 2010: results of the univariate analysis (total).

	2006	2010	𝑃
Number	27,723	38,008
Birth weight (g)	2950.84 (510.24)	2937.52 (505.12)	<0.0001
Gestational age at delivery (wks)	39.087 (1.933)	38.985 (1.930)	<0.0001
Maternal height (cm)	158.338 (5.436)	158.471 (5.492)	0.006
Maternal age (yr)	31.119 (5.015)	32.002 (5.209)	0.006
Pregestational BMI	21.057 (3.347)	21.092 (3.44)	0.041
Weight gain during pregnancy (kg)	9.846 (4.454)	9.842 (4.333)	0.744
IVF-ET	637 (2.3%)	1,672 (4.4%)	<0.0001
Primiparity	14,693 (53.0%)	20,676 (54.4%)	<0.0001
Smoking	1,807 (5.3%)	1,672 (4.4%)	<0.0001
Induction of labor	6,542 (23.6%)	10,224 (26.9%)	<0.0001
Cesarean delivery	6,986 (25.2%)	10,832 (28.5%)	<0.0001

() represents the standard deviation or %.