morbidity and mortality associated with hypertension in pregnancy

Last edited 08/2019

Around 10% of pregnancies are thought to be complicated by hypertensive disorders with evidence of increase in the rate (1).

• rates for chronic hypertension during pregnancy is reported to be between 0.6% and 2.7%
• rates for gestational hypertension  is between 4.2% and 7.9% and is thought to be under reported
• rates of pre-eclampsia is reported to be in the range of 4.2% to 7.9%. The rate depends on the parity with the rate being
• 4.1% for  primigravid women
• 1.7% for women in their second pregnancy (1)
• incidence of eclampsia is around 2.7 cases per 10,000 births (2)

Hypertensive disorders during pregnancy may also result in substantial maternal morbidity (1)

• a UK study reported that one-third of severe maternal morbidity was a consequence of hypertensive conditions
• a study from one region of the UK reported that 1 in 20 (5%) women with severe pre-eclampsia or eclampsia were admitted to intensive care

Hypertensive disorders also carry a risk for the baby (1)

• the UK perinatal mortality report revealed, 1 in 20 (5%) stillbirths in infants without congenital abnormality occurred in women with pre-eclampsia
• the contribution of pre-eclampsia to the overall preterm birth rate is substantial;
  • 1 in 250 (0.4%) women in their first pregnancy will give birth before 34 weeks as a consequence of pre-eclampsia and 8-10% of all preterm births result from hypertensive disorders
  • half of women with severe pre-eclampsia give birth preterm
  • small-for-gestational-age babies (mainly because of fetal growth restriction arising from placental disease) are common, with 20-25% of preterm births and 14-19% of term births in women with pre-eclampsia being less than the tenth centile of birth weight for gestation

Although the rate of eclampsia seems to have decreased in UK, hypertension in pregnancy has been recorded as the leading cause of maternal death the UK, Europe and elsewhere (1).

Cardiovascular risk in women who have had a hypertensive disorder of pregnancy

Type of hypertension in current or previous pregnancy (3)

(a) Risks described are overall estimates, summarised from risk ratios, odds ratios and hazard ratios.

(b) Increased risk is compared to the background risk in women who did not have hypertensive disorders during pregnancy. Absolute risks are not reported, because these will vary considerably, depending on the follow-up time (range from 1 to 40 years postpartum).

Reference:

• (1) NICE (August 2010). Hypertension in pregnancy - the management of hypertensive disorders during pregnancy
• (2) Knight M; UKOSS. Eclampsia in the United Kingdom 2005. BJOG. 2007;114(9):1072-8
• (3) NICE (June 2019). Hypertension in pregnancy: diagnosis and management