Temporal trends of preterm birth in Shenzhen, China: a retrospective study

Table 3 Distribution of Risk Factors for Preterm Birth (PTB) in Shenzhen, China, 2003- 2012

	Incidence rates (%)
	2003-2007	2008-2012
Preterm birth ^a
Overall-PTB	5.38	5.79
PROM-PTB	0.43	0.59
S-PTB	3.24	2.84
MI-PTB	1.81	2.43
Maternal age (years)
21-35	90.71	87.78
≤ 20	4.62	6.54
≥ 36	4.66	5.68
Maternal education
Less than high school	50.11	39.66
High school and college	32.79	37.66
Bachelor	16.26	20.51
Postgraduate	0.83	2.17
Parity
0	66.57	59.40
≥ 1	33.43	40.10
Missing	0.00	0.50
APNCU index ^b
Inadequate	54.81	40.93
Intermediate	14.84	30.14
Appropriate	15.61	14.4
Appropriate plus	14.73	15.3
Missing	0.00	0.02
Maternal chronic conditions
No	99.81	99.76
Yes	0.19	0.24
Gestational hypertension
No	99.79	99.56
Yes	0.21	0.44
Preeclampsia or eclampsia
No	98.67	98.92
Yes	1.33	1.08
Infant sex
Female	45.13	46.02
Male	54.85	53.97
Hermaphrodite	0.02	0.01

^aOverall-PTB all preterm births, PROM-PTB preterm birth following premature rupture of membranes, S-PTB preterm birth due to spontaneous preterm labor, MI-PTB medically induced preterm birth
^bAPNCU the adequacy of prenatal care utilization

ISSN: 1742-4755