Table 1

 Means (SD) and percentages (95% confidence intervals) of pregnancy characteristics according to whether the offspring pregnancy (n = 7080) was complicated by a hypertensive disease

Pregnancy not complicated by any hypertensive disease*(n = 5295)Pregnancy complicated by pre-eclampsia(n = 201)p Value†Pregnancy complicated by gestational hypertension(n = 1584)p Value‡
*Pregnancies uncomplicated by either manifestation of pregnancy induced hypertension (either pre-eclampsia or gestational hypertension) are reference group for both. †For difference between pregnancies complicated by pre-eclampsia and those uncomplicated by either manifestation of pregnancy induced hypertension. ‡For difference between pregnancies complicated by gestational hypertension and those uncomplicated by either manifestation of pregnancy induced hypertension. Robust standard errors were used to take account of non-independence of data.
Maternal age at delivery mean (SD) years25.5 (5.3)24.8 (4.9)0.0425.1 (4.7)0.001
Maternal age categories
    <2012.2 (11.3 to 13.1)15.9 (11.2 to 21.7)10.2 (8.7 to 11.9)
    21–3581.4 (80.3 to 82.4)81.1 (75.0 to 86.3)86.2 (84.4 to 87.8)
    ⩾366.4 (5.8 to 7.1)3.0 (1.1 to 6.4)0.053.7 (2.8 to 4.7)<0.001
Maternal smoking in pregnancy% (95% CI)41.1 (39.4 to 42.9)29.7 (23.3 to 36.9)0.00333.0 (30.0 to 36.2)<0.001
Nulliparous % (95%CI)38.9 (37.6 to 40.2)74.5 (68.0 to 80.1)<0.00160.6 (58.3 to 62.8)<0.001
Grandmother had pre-eclampsia in mothers pregnancy% (95% CI)3.6 (3.1 to 4.1)8.1 (4.8 to 13.4)0.0044.8 (3.8 to 6.1)0.05
Grandmother had gestational hypertension in mothers pregnancy% (95% CI)13.6 (12.7 to 14.6)21.3 (16.0 to 27.7)0.00319.0 (17.1 to 21.1)<0.001
Birth weight of offspring mean (SD) grams3302.8 (548.6)3036.6 (678.9)<0.0013330.8 (551.5)0.10
Gestational age of offspring mean (SD) weeks39.5 (1.9)38.5 (2.5)<0.00139.5 (2.0)0.67
Standard deviation (Z) score of offspring birth weight for gestational age−0.06 (1.00)−0.28 (1.01)0.003−0.04 (0.99)0.29