Table 1. Selected characteristics of IUGR newborns and controls.

Characteristics	Cases (n=22)	Controls (n=22)	P-valuea
Sex
Male	9	9	1.000
Female	13	13
Birth weight (kg)b	2.318±0.318	3.195±0.408	0.000**
Birth length (cm)b	47.500±2.133	50.640±1.093	0.000**
Ponderal index (g/cm3 × 100)b	2.175±0.375	2.459±0.294	0.008**
Gestational age (week)b	37.468±2.587	39.214±0.642	0.004**
Maternal age (year)b	27.82±4.02	26.50±2.69	0.208
Paternal age (year)b	27.86±3.23	28.45±2.77	0.518
Pre-pregnant BMIb	19.05±2.21	19.08±1.43	0.957
Smoking during pregnancy
Yes	0	0	1.000
No	22	22
Drinking during pregnancy
Yes	0	0	1.000
No	22	22
Education
Junior middle school	10	1	0.001**
High school	5	2
College	7	19
Monthly income per family
<5000 RMB	11	6	0.122
≥5000 RMB	11	16
Pregnancy complicationsc
Yes	5	2	0.410
No	17	20

**P<0.01.

^aP-value calculated using the χ²-test and t-test.

^bValues are shown as mean±SD.

^cPregnancy complications include pregnancy-induced hypertension, diabetes, infection, and intrahepatic cholestasis syndrome.