Pregnancy hypertension rates | |||||
---|---|---|---|---|---|
Risk factor | 2001 N=84 302 n (row %) | 2012 N=96 051 n (row %) | Trend over time p Value | Rate difference* | Rate ratio (95% CI)* |
All women | 8356 (9.9) | 7433 (7.7) | <0.0001 | −2.2 | 0.78 (0.76 to 0.80) |
Maternal risk factors | |||||
Nulliparity | 4827 (13.7) | 4362 (10.3) | <0.0001 | −3.4 | 0.75 (0.72 to 0.78) |
Maternal age ≥35 years | 1524 (10.0) | 1907 (8.5) | <0.0001 | −1.6 | 0.84 (0.79 to 0.90) |
Maternal age <20 years | 394 (10.4) | 304 (9.6) | 0.18 | −0.8 | 0.93 (0.80 to 1.07) |
Diabetes (any) | 623 (15.6) | 1058 (12.0) | <0.0001 | −3.6 | 0.77 (0.70 to 0.84) |
Morbid obesity | 56 (45.2) | 196 (24.2) | <0.0001 | −20.9 | 0.54 (0.43 to 0.68) |
ART | 200 (15.1) | 283 (9.5) | <0.0001 | −5.6 | 0.63 (0.53 to 0.75) |
Smoking | 1183 (7.6) | 763 (6.9) | <0.0001 | −0.7 | 0.91 (0.83 to 0.99) |
Multiple births | 292 (20.1) | 226 (17.2) | 0.0013 | −2.9 | 0.85 (0.73 to 1.00) |
Autoimmune diseases | 67 (16.5) | 53 (13.1) | 0.007 | −3.4 | 0.79 (0.57 to 1.11) |
Previous pregnancy hypertension† | 1144 (36.3) | 1249 (31.8) | 0.0001 | −4.5 | 0.88 (0.82 to 0.94) |
Asian ethnicity | 558 (7.0) | 935 (5.3) | <0.0001 | −1.6 | 0.75 (0.68 to 0.83) |
Chronic hypertension | 132 (24.1) | 160 (25.7) | 0.48 | 1.6 | 1.07 (0.87 to 1.30) |
Renal disease | 49 (26.5) | 52 (18.7) | 0.009 | −7.8 | 0.71 (0.50 to 1.00) |
Summer birth | 1800 (8.9) | 1722 (7.4) | <0.0001 | −1.5 | 0.83 (0.78 to 0.89) |
Obstetric factors | |||||
Gestational age, weeks | |||||
<37 | 1005 (18.4) | 1203 (18.1) | 0.35 | −0.3 | 0.98 (0.89 to 1.07) |
37 | 716 (17.0) | 929 (14.2) | <0.0001 | −2.8 | 0.84 (0.76 to 0.91) |
38 | 1562 (12.5) | 1524 (8.6) | <0.0001 | −3.9 | 0.69 (0.65 to 0.74) |
39 | 1805 (9.5) | 1788 (6.3) | <0.0001 | −3.2 | 0.66 (0.62 to 0.71) |
40 | 2218 (8.3) | 1404 (5.8) | <0.0001 | −2.5 | 0.70 (0.66 to 0.75) |
≥41 | 1047 (6.4) | 584 (4.6) | <0.0001 | −1.8 | 0.72 (0.65 to 0.80) |
Planned deliveries (any) | 5719 (18.0) | 5604 (12.8) | <0.0001 | −5.2 | 0.71 (0.69 to 0.74) |
Prelabour CS | 1484 (13.6) | 1819 (10.3) | <0.0001 | −3.3 | 0.76 (0.71 to 0.81) |
Labour inductions | 4235 (20.3) | 3785 (14.5) | <0.0001 | −5.8 | 0.72 (0.69 to 0.74) |
Planned delivery at 37–39 weeks | 2932 (19.5) | 3281 (12.6) | <0.0001 | −7.0 | 0.64 (0.62 to 0.67) |
*Among women with the specified risk factor in 2012 compared with 2001.
†Among multipara.
ART, assisted reproductive technology; CS, caesarean section.