Association between ABO blood groups and preeclampsia

Figures & data

Table 1. Comparison of sociodemographic, medical, and obstetric characteristics between pregnant women with and without preeclampsia/eclampsia.

Variable	Cases	Controls
	(n = 253)	(n = 457)
Sociodemographic
Education, junior high or less	133 (52.6%) *	156 (34.1%)
Occupation, economically active	103 (43.5%)	268 (58.9%) *
Medical history
Preeclampsia/eclampsia	52 (20.6%) *	23 (5.0%)
Hypertension	28 (11.1%) *	8 (1.8%)
Type 2 diabetes	5 (2.0%)	8 (1.8%)
Pre-pregnancy overweight/obesity	196 (77.5%) *	272 (59.5%)
Obstetric
Parity, nulliparous	85 (33.6%)	169 (37.0%)
Inter-pregnancy interval≥10 years in women with≥1 pregnancy	15 (8.9%)	19 (6.6%)
Multiple gestation	6 (2.4%)	8 (1.8%)
Gestational age at the last antenatal visit (weeks)	34.2 ± 4.2	33.1 ± 6.4
Aspirin use during pregnancy	10 (4.0%)	24 (5.3%)
Fetal sex (male)	151 (59.7%) *	201 (44.0)

*p < 0.0001.

Table 2. Comparison of blood group and factor type between pregnant women with and without preeclampsia/eclampsia (cases, n = 253; controls, n = 457).

Variable	Cases (n = 253)	Controls (n = 457)
Clinical
Systolic blood pressure at first antenatal visit (mm Hg)	107.5 ± 13.4 **	101.2 ± 8.9
Diastolic blood pressure at first antenatal visit (mm Hg)	67.8 ± 9.9 **	64.0 ± 6.3
Mean arterial pressure at the first antenatal visit (mm Hg)	81.2 ± 10.8 **	76.3 ± 6.3
Gestational diabetes	29 (11.6%) *	28 (6.2%)
Weight gain (kg)	8.7 ± 5.8 **	7.3 ± 5.0
Perinatal outcome
Gestational age at delivery (weeks)	36.2 ± 3.3 **	39.0 ± 1.8
Birth weight (g)	2,689.0 ± 745.1 **	3,214.8 ± 500.0
Apgar score in 1st minute	7.5 ± 1.6 *	8.0 ± 0.7
Apgar score at 5th minute	8.5 ± 1.5 **	9.0 ± 0.4

*p < 0.01, ** p < 0.001.

Table 3. Comparison of blood group and factor type between pregnant women with and without preeclampsia/eclampsia (cases, n = 253; controls, n = 457).

	Multiparous			Nulliparous
ABO blood groups	Cases (n = 168)	Controls (n = 288)	p-value	Cases (n = 85)	Controls (n = 169)	p-value
Type O	111 (66.1%)	170 (59.0%)	0.152	45 (52.9%)	104 (61.5%)	0.223
Type A	31 (18.5%)	69 (24.0%)		22 (25.9%)	34 (20.1%)
Type B	22 (13.1%)	32 (11.1%)		11 (12.9%)	23 (13.6%)
Type AB	4 (2.4%)	17 (5.9%)		7 (8.2%)	8 (13.6%)
Rh + blood group	164 (97.6%)	282 (97.9%)	1.000	84 (98.8%)	164 (97.0%)	0.667

Table 4. Crude and adjusted odds ratios between ABO blood group and preeclampsia. Multivariate logistic regression model among multiparous pregnant women (cases, n = 168; controls, n = 288).

	Odds ratio (95% confidence interval)
Blood group	Crude	Adjusted^a
Type O	1.0	1.0
Type A	0.7 (0.4-1.1)	0.6 (0.3-1.0)
Type B	1.1 (0.6-1.9)	1.1 (0.6-2.2)
Type AB	0.4 (0.1-1.1)	0.3 (0.1-1.1)

a By maternal age, inter-pregnancy interval, medical history of preeclampsia/eclampsia, chronic hypertension, type 2 diabetes, pre-pregnancy overweight/obesity, mean blood pressure at the first antenatal visit (first trimester), multiple gestation, aspirin use during pregnancy, and fetal sex.

Table 5. Crude and adjusted odds ratios between ABO blood group and preeclampsia. Multivariate logistic regression model among nulliparous pregnant women (cases, n = 85; controls, n = 169).

	Odds ratio (95% confidence interval)
Blood group	Crude	Adjusted^a
Type O	1.0	1.0
Type A	1.5 (0.8-2.8)	1.3 (0.6-2.7)
Type B	1.1 (0.5-2.5)	0.9 (0.4-2.3)
Type AB	2.0 (0.7-5.9)	2.2 (0.6-7.2)

^aBy maternal age, chronic hypertension, pre-pregnancy overweight/obesity, mean blood pressure at the first antenatal visit (first trimester), multiple gestation, aspirin use during pregnancy, and fetal sex.

Figure 1. Association between the ABO blood groups and preeclampsia: aim, methods and results.