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

Table 1 Ten most common birth defects and their prevalence rate at the Obstetrics and Gynecology Hospital of Fudan University, 2008-2014, n (%)

Birth defects	2008	2009	2010	2011	2012	2013	2014	Total (average prevalence)
Congenital heart disease	26 (0.394)	31 (0.470)	28 (0.286)	36 (0.280)	29 (0.196)	35 (0.232)	44 (0.470)	229 (0.277)
Polydactyly/syndactyly	17 (0.258)	27 (0.409)	21 (0.215)	35 (0.272)	36 (0.243)	41 (0.271)	41 (0.410)	218 (0.263)
Hypospadias	14 (0.212)	7 (0.106)	10 (0.102)	12 (0.093)	19 (0.128)	14 (0.093)	11 (0.106)	87 (0.105)
Orofacial clefts	4 (0.060)	11 (0.167)	13 (0.133)	5 (0.039)	14 (0.094)	15 (0.100)	17 (0.167)	79 (0.095)
Congenital ear malformations	3 (0.045)	9 (0.136)	17 (0.174)	13 (0.101)	6 (0.041)	6 (0.040)	5 (0.136)	59 (0.071)
Down syndrome	1 (0.015)	2 (0.030)	4 (0.041)	3 (0.023)	10 (0.067)	6 (0.040)	2 (0.030)	28 (0.034)
Strephenopodia/strephexopodia	1 (0.015)	5 (0.076)	9 (0.092)	3 (0.023)	2 (0.014)	3 (0.020)	1 (0.006)	24 (0.029)
intestinal atresia/stenosis	5 (0.076)	2 (0.030)	5 (0.051)	1 (0.008)	3 (0.020)	6 (0.040)	2 (0.012)	24 (0.029)
Chromosomal disease	5 (0.076)	0 (0)	1 (0.010)	1 (0.008)	0 (0)	5 (0.033)	4 (0.023)	15 (0.019)
kidney malformations	2 (0.030)	2 (0.030)	2 (0.020)	0 (0)	0 (0)	0 (0)	7 (0.041)	13 (0.016)
Number of births	6596	6602	9786	12844	14832	15110	17044	82814

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.