A study has found that hypertensive disorder of pregnancy that triggers abnormally high blood pressure is associated with an increased risk of death in offspring.
The disorder, called hypertensive disorder of pregnancy, is a group of conditions, including pre-eclampsia, eclampsia, and hypertension, which can trigger abnormally high blood pressure in pregnancy. The group of conditions affects up to 10% of pregnancies worldwide and is one of the leading causes of illness and death among mothers and their infants.
Research has shown that affected offspring may acquire conditions such as metabolic syndrome (a combination of diabetes, high blood pressure, and obesity), immune diseases, and neurodevelopment and psychiatric disorders. Despite this, evidence of the impact on offspring from birth to adolescence is lacking.
The study was published by The BMJ.
Examining data from 2.4 million people
The lack of evidence drove researchers to examine hypertensive disorder of pregnancy in mothers with overall and cause-specific mortality in offspring from birth to young adulthood.
The research team used data from Danish national health registers, tracking 2.4 million individuals born in Denmark between 1978 and 2018 from birth until the date of death, emigration or 31 December 2018, whichever came first.
The team focussed on all-cause mortality, followed by 13 specific causes of death in offspring from birth to young adulthood, up to age 41 years. This included cardiovascular diseases, cancer, mental and behavioural disorders, diseases of the nervous and musculoskeletal systems, and birth defects.
They also accounted for potentially influential factors, including sex of offspring, mothers’ age at childbirth, education level, income, living arrangements, smoking during pregnancy, and medical history.
Hypertensive disorder of pregnancy and offspring outcome
The researchers included 2,437,718 offspring in the analysis, 102,095 (4.2%) were exposed to hypertensive disorder of pregnancy before birth, including 68,362 (2.8%) exposed to pre-eclampsia or eclampsia and 33,722 (1.4%) exposed to hypertension.
Following the 19-year follow-up period, deaths occurred in 781 (59 per 100,000 person-years) offspring born to mothers with pre-eclampsia, 17 (134 per 100,000 person-years) born to mothers with eclampsia, 223 (44 per 100,000 person-years) born to mothers with hypertension, and 19,119 (42 per 100,000 person-years) born to mothers with no hypertensive disorder of pregnancy.
Offspring exposed to the disorder in pregnancy also had a 26% higher risk of all-cause mortality than non-exposed individuals. The associated increased risk for pre-eclampsia, eclampsia, and hypertension was 29%, 188%, and 12%.
A strong association was found in mothers with hypertensive disorder of pregnancy and a history of diabetes or low education level. Furthermore, increased risks were recorded for several cause-specific deaths; deaths from digestive diseases and conditions in the perinatal period more than doubled in the offspring exposed to hypertensive disorder of pregnancy, whilst deaths from endocrine, nutritional, metabolic and cardiovascular diseases increased by over 50%. There was no link found between hypertensive disorder of pregnancy and offspring’s risk of cancer.
As this study is observational, the researchers acknowledge that outside factors such as smoking and obesity could be contributing factors to offspring death. They also pointed out that Denmark has universal health coverage with high-quality health services, which might limit the generalisability of the findings.