Table 1 Maternal characteristics by HDP status during pregnancy

Age at delivery, years

30.46 ± 5.57

31.89 ± 5.47

33.05 ± 5.55

30.17 ± 5.62

30.36 ± 5.44

SBP, mmHg

143.69 ± 16.23

141.59 ± 16.11

157.50 ± 21.48

147.17 ± 17.40

138.86 ± 12.30

DBP, mmHg

93.70 ± 11.55

92.35 ± 11.50

102.08 ± 13.90

95.92 ± 12.30

90.65 ± 9.34

Blood pressure categories at birth admission, n (%)

 Normal

10,360(2.63)

1230(3.67)

91(1.02)

4800(2.43)

4239(2.76)

 Elevated

9564(2.43)

1105(3.30)

76(0.85)

3898(1.98)

4485(2.92)

 Stage1

57,302(14.57)

6012(17.96)

632(7.07)

23,663(11.99)

26,995(17.58)

 Non-severe stage2

240,487(61.14)

20,173(60.27)

3790(42.39)

108,501(54.98)

108,023(70.33)

 Severe stage2

75,640(19.23)

4951(14.79)

4352(48.67)

56,495(28.63)

9842(6.41)

Gestational age at delivery, weeks

37.86 ± 2.34

37.88 ± 2.17

35.90 ± 3.11

37.38 ± 2.61

38.57 ± 1.63

Antenantal care visits, n (%)

 None

4485(1.14)

299(0.89)

154(1.72)

2826(1.43)

1206(0.79)

 1–4

43,136(10.97)

2624(7.84)

1139(12.74)

25,346(12.84)

14,027(9.13)

 5–7

111,479(28.34)

8071(24.11)

2351(26.29)

60,138(30.47)

40,919(26.64)

 >=8

218,821(55.63)

21,193(63.32)

4567(51.08)

100,930(51.14)

92,131(59.99)

 Unknown

15,432(3.92)

1284(3.84)

730(8.16)

8117(4.11)

5301(3.45)

Region of China, n (%)

 East

116,044(29.50)

11,044(33.00)

3185(35.62)

53,196(26.95)

48,619(31.66)

 Central

159,289(40.50)

13,303(39.74)

3284(36.73)

81,160(41.12)

61,542(40.07)

 West

118,020(30.00)

9124(27.26)

2472(27.65)

63,001(31.92)

43,423(28.27)

Hospital level, n (%)

 Unknown

18,593(4.73)

1320(3.94)

183(2.05)

10,400(5.27)

6690(4.36)

 Level 1

16,999(4.32)

984(2.94)

193(2.16)

9133(4.63)

6689(4.36)

 Level 2

152,599(38.79)

12,325(36.82)

2543(28.44)

74,195(37.96)

62,816(40.90)

 Level 3

205,162(52.16)

18,842(56.29)

6022(67.35)

102,909(52.14)

77,389(50.39)

Marital status, n (%)

 Unmarried

5420(1.38)

349(1.04)

75(0.84)

2814(1.43)

2181(1.42)

 Married

387,870(98.61)

33,115(98.94)

8863(99.13)

194,515(98.56)

151,377(98.56)

 Unknown

63(0.02)

7(0.02)

3(0.03)

28(0.01)

25(0.02)

Delivery method, n (%)

 Vaginal

127,913(32.52)

11,464(34.25)

1484(16.60)

48,037(24.34)

66,928(43.58)

 Caesarean section

265,440(67.48)

22,007(65.75)

7457(83.40)

149,320(75.66)

86,656(56.42)

Parity, n (%)

 Nulliparous

216,966(55.16)

16,469(49.20)

3685(41.21)

112,779(57.14)

84,033(54.71)

 Multiparous

176,240(44.80)

16,993(50.77)

5255(58.77)

84,494(42.81)

69,498(45.25)

 Unknown

147(0.04)

9(0.03)

1(0.01)

84(0.04)

53(0.03)

Education, n (%)

 No formal education

3201(0.81)

232(0.69)

89(1.00)

1752(0.89)

1128(0.73)

 Primary school

15,892(4.04)

1181(3.53)

512(5.73)

8310(4.21)

5889(3.83)

 Middle school

105,855(26.91)

7348(21.95)

2292(25.63)

55,731(28.24)

40,484(26.36)

 High school

106,110(26.98)

8769(26.20)

2406(26.91)

54,761(27.75)

40,174(26.16)

 College or higher

153,889(39.12)

15,133(45.21)

3462(38.72)

72,442(36.71)

62,852(40.92)

 Unknown

8406(2.14)

808(2.41)

180(2.01)

4361(2.21)

3057(1.99)

Application of magnesium sulfate, n (%)

101,649 (25.84)

4036 (12.06)

4653(52.04)

79,044(40.05)

13,916(9.06)

Diabetes, n (%)

64,085(16.29)

7584(22.66)

2185(24.44)

28,132(14.25)

26,184(17.05)

Kidney disease, n (%)

4611(1.17)

427(1.28)

330(3.69)

2862(1.45)

992(0.65)

Preterm delivery at < 37 weeks, n (%)

70,162(17.85)

4882(14.60)

4024(45.15)

50,587(25.65)

10,669(6.95)

SGA (< 10th percentile), n (%)

67,643(17.22)

4016(12.02)

2266(25.47)

45,264(22.98)

16,097(10.49)

Stillbirth, n (%)

5375(1.37)

413(1.23)

365(4.08)

3734(1.89)

863(0.56)

Neonatal death, n (%)

1129(0.29)

72(0.22)

79(0.89)

785(0.40)

193(0.13)

Low Apgar score, n (%)

2797(0.73)

145(0.44)

158(1.87)

1937(1.01)

557(0.37)