Table 2.

Proportion of characteristics in cases and controls

Characteristics	Cases		Controls		Chi-square and P-value #
	No.	%	No.	%
Sex of the baby
Male	49	46.2	59	61.5	χ2=4.11
Female	57	57.8	37	38.5	P=0.04 (Sig)
Induced abortion
0	106	97.3	98	96.1	P=0.71# (NS)
1	3	2.7	4	3.9
Spontaneous abortion
0	87	79.8	102	100	χ2=20.9
≥1	22	20.2	0	0	P<0.0001 (Sig)
Previous preterm
0	104	95.4	102	100	P=0.06# (NS)
≥1	5	4.8	0	0
Previous full term
0	65	59.6	0	0	χ2=90.73
1	24	22.1	50	49	df=3
2	16	14.7	30	29.4	P<0.0001 (Sig)
3	4	3.7	22	21.6
Number of previous pregnancies
0	54	49.5	49	48.0	χ2=8.68
1	24	22.0	29	28.4	df=4
2	17	15.6	21	20.5	P=0.07 (NS)
3	10	9.8	3	2.94
≥4	4	3.6	0	0
Previous live births
0	65	59.6	50	49	χ2=7.29
1	21	19.3	35	34.3	df=3
2	19	17.4	16	15.7	P=0.06 (NS)
3	4	3.7	1	0.98
Blood group
O	25	22.9	25	24.5
A	20	18.3	18	17.6	χ2=2.30
B	26	23.9	21	20.6	df=5
A1	2	1.8	0	0.9	P=0.81 (NS)
AB	2	1.8	4	3.9
A1B	1	0.9	0	0
Rh factor
Positive	72	94.7	66	95.7	P=1.00# (NS)
Negative	4	5.3	3	4.3
Hypertension
Yes	10	9.2	4	3.9	χ2=1.58
No	99	90.8	98	96.1	P=0.21 (NS)
Genitourinary tract infection
Yes	12	11.0	12	11.8	χ2=0.002
No	97	89.0	90	88.2	P=0.96 (NS)
Tobacco/alcohol
Yes	2	1.8	0	0
No	107	98.2	102	100	P=0.50# (NS)
Onset of prenatal care
Prior to 20 weeks	56	51.4	61	59.8	χ2=5.74
Between 20-25 weeks	47	43.1	31	30.4	df=3
After 25 weeks	3	2.8	8	7.8	P=0.12 (NS)
No care	3	2.8	2	2
No. of prenatal visits
≥6	31	28.4	47	46.1	χ2=6.30
<6	78	71.6	55	53.9	P=0.01 (Sig)

# P-values calculated from fisher exact test