In a previous study, it was found that children exposed to maternal hypertensive disorders during gestation have increased risks of premature birth, foetal growth restriction, and cardiovascular risk factors later in life. However, there is limited evidence for a direct link with severe cardiovascular disease.
A new study explored this link by focusing on ischaemic heart disease and stroke. The study on 5.8 million children has discovered that children exposed to maternal hypertensive disorders during pregnancy have a higher risk of stroke for four decades. This signifies that hypertensive disorders during pregnancy are associated with increased risks of stroke and potentially heart disease in offspring.
Offspring exposed to maternal hypertensive pregnancy disorders had 29%, and 33% increased risks of ischaemic heart disease and stroke, respectively. The affiliations were independent of preterm birth and fetal development limitation. In the sibling analyses, the affiliation stayed for stroke yet not for ischaemic heart disease.
The study linked national registers from two countries. Live singleton births in Sweden (1973 to 2014) and Finland (1987 to 2014) were followed for ischaemic heart disease and stroke until 2014. It then identified hypertensive pregnancy disorders, including high blood pressure (starting before or during pregnancy) and preeclampsia (high blood pressure and organ damage).
Scientists then estimated the risks of ischaemic heart disease and stroke related to high blood pressure conditions during pregnancy. They adjusted their analyses for several factors that could influence the relationships, such as the child’s year of birth, sex, and congenital anomalies and the mother’s age, parity, marital status, education level, body mass index, smoking during early pregnancy, and family history of cardiovascular disease.
The same analyses were performed after excluding children with preterm birth or foetal growth restriction. In sibling analyses, scientists controlled the potential effect of unmeasured genetic and environmental familial factors. These analyses included sibling pairs discordant for both the exposure (hypertensive pregnancy disorders) and the outcome (ischaemic heart disease/stroke).
Among more than 5.8 million singletons in the study, 218,322 (3.76%) were born to mothers with hypertensive disorders during pregnancy. During up to 41 years of follow-up, 2,340 (0.04%) offspring were diagnosed with ischaemic heart disease, and 5,360 (0.09%) were diagnosed with stroke.
Study author Dr. Fen Yang, Ph.D. student, Karolinska Institutet, Stockholm, Sweden, said, “The sibling analyses suggest that shared genetic or environmental factors were the main contributors to the association between hypertensive pregnancy disorders and the risk of ischaemic heart disease. However, the increased risk of stroke persisted, indicating the possibility of direct intrauterine effects.”
“This was one of the very few studies in this area, and more research is needed. It was an observational study, and we cannot make any conclusions about causality. If further studies support our findings, steps could be taken to prevent cardiovascular disease in offspring exposed to hypertensive pregnancy disorders – for example, by focussing on maternal health and screening children for risk factors like high blood pressure early in life.”
The research is presented at ESC Heart & Stroke 2021, an online scientific conference of the European Society of Cardiology (ESC).