Observed prevalence and risk factors of birth defects in Shanghai, China

Table 2 Multiple logistic regression of risk factors for birth defects, 2008-2014

Factors	Delivery	Cases (%)	OR (95%CI) Enter	P value
Maternal age (yr)
< 20	274	2 (0.7)	1	-
20-	7353	82 (1.1)	1.951 (0.473, 8.045)	-
25-	41861	392 (0.9)	1.818 (0.446, 7.406)	-
30-	26285	249 (0.9)	1.686 (0.413, 6.886)	-
35-	6080	74 (1.2)	1.806 (0.435, 7.494)	-
40-	961	20 (2.1)	2.676 (0.611, 11.715)	-
Parity order	-	-	0.835 (0.687, 1.014)	0.069
Gravidity order	-	-	1.099 (1.024, 1.178)	0.009
Gender
Male	42828	484 (1.1)	1
Female	39986	335 (0.8)	0.710 (0.616, 0.818)	< 0.001
Gestational age (wk)
≥ 37	75750	556 (0.7)	1
28-37	7064	263 (3.7)	1.905 (1.501, 2.418)	< 0.001
Birth weight
Normal	73133	536 (0.7)	1
ELBW and VLBW and LBW	4742	242 (5.1)	3.844 (3.004, 4.919)	< 0.001
Macrosomia	4939	41 (0.8)	1.090 (0.790, 1.503)	0.601
Plurality
Singletons	79440	691 (0.9)	1
Twins or higher order multiple pregnancies	3374	128 (3.8)	1.477 (1.107, 1.969)	0.008
Household registration
Permanent population	68930	617 (0.9)	1
Migrant population	13884	202 (1.5)	1.380 (1.167, 1.632)	< 0.001
Delivery mode
Vaginal delivery	38236	291 (0.8)	1
Cesarean delivery	44578	528 (1.2)	1.184 (1.016, 1.380)	0.031

ELBW: Extremely low birth weight; VLBW: Very low birth weight; LBW: Low birth weight.