National Women's Annual Clinical Report 2010

5.6 Hypertensive disease
Methods
The following definitions of hypertension in pregnancy have been used in this report:
Gestational hypertension: Gestational hypertension (GH) is a blood pressure
systolic ≥140 and / or diastolic ≥ 90 mmHg on two or more consecutive occasions
at least 4 hours apart or one measurement systolic BP ≥170 and or diastolic BP
≥110 mmHg.
Preeclampsia: Gestational hypertension accompanied by proteinuria measured
as ≥2+ protein on one dipstick sample or Protein Creatinine Ratio (PCR) ≥30 on a
spot urine sample, or a 24 hour collection ≥0.3g in 24 hours.
Chronic hypertension: diastolic BP >90mmHg at booking or a medical history of
essential hypertension. Includes women with superimposed pre-eclampsia if these
are not categorised separately.
Super imposed preeclampsia: The development of preeclampsia in a patient
with chronic hypertension.
The cleaning of hypertension data involves reconciling data from booking history,
indication for induction and operative birth, reason for admission to the ward or to High
Dependency Unit, data collected at birth and coded data from the Decision Support Unit.
Findings
The overall rate of hypertensive disease in pregnancy (8.5%) is similar to the rate in 2009.
It still remains a very common medical disorder in pregnancy. Chronic hypertension is
more common in the multiparous population, with gestational hypertension and
preeclampsia being predominant in nulliparous women. Women with increased BMI had
higher rates of hypertensive disease in pregnancy, especially if their BMI was greater than
40. Thirty-five percent of women with a BMI over 45 had hypertensive disease in
pregnancy.
There was 1 reported case of eclampsia in 2010 (0.2% of hypertensive pregnancies) and
this occurred postpartum.
Table 33: Hypertensive disease in pregnancy (2010)
All women
Nullipara
Multipara
N=7709
n=3650
n=4059
n % n % n %
Any hypertensive disease 653 8.5 362 9.9 291 7.2
Gestational hypertension 234 3.0 145 4.0 89 2.2
Chronic hypertension 164 2.1 56 1.5 108 2.7
Chronic hypertension
superimposed preeclampsia
with
24 0.3 8 0.2 16 0.4
Preeclampsia 231 3.0 153 4.2 78 1.9
Eclampsia 1 0.01 0 1 0.02
Hypertensive disease is associated with an increase in interventions to interrupt
pregnancy. Fifty six percent of normotensive women went into labour spontaneously,
compared with only 26%, 13% and 31% of the women with gestational hypertension, preeclampsia
or chronic hypertension respectively. A diagnosis of preeclampsia, chronic
hypertension or superimposed preeclampsia is associated with a high risk of Caesarean
section birth (57%, 36% and 63% respectively).
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