Prior to the late 1970s, couples who had difficulties conceiving children had limited options available to aid them. However, in 1978 advances in medicine gave rise to assisted reproductive technologies (ART) that to date has helped millions of individuals and families who could not conceive naturally. Children conceived using ART makeup 1.7% of all infants born in the U.S. every year and currently over six million persons worldwide. The most common ART methods are in vitro fertilization and intracytoplasmic sperm injection, which can expose the gamete and embryo to a variety of environmental factors before implantation.
Now, a new study from investigators at the University of Bern in Switzerland describes how children conceived through ART may be at an increased risk of developing arterial hypertension early in life, among other cardiovascular complications. Findings from the new research were published recently in the Journal of the American College of Cardiology through an article titled “Association of Assisted Reproductive Technologies With Arterial Hypertension During Adolescence.”
The study authors assessed the circulatory system of 54 young, healthy ART adolescents (mean age 16) by measuring ambulatory blood pressure, as well as plaque build-up, blood vessel function, and artery stiffness. Body mass index, birth weight, gestational age and maternal BMI, smoking status, and cardiovascular risk profile were similar between the ART adolescents and 43 age- and sex-matched control participants.
Interestingly, using 24-hour ambulatory blood pressure monitoring, researchers discovered that ART adolescents had both a higher systolic and diastolic blood pressure than the control participants of natural conception at 119/71 mmHg versus 115/69, respectively. Most importantly, eight of the ART adolescents reached the criteria for the diagnosis of arterial hypertension (over 130/80 mmHg) whereas only one of the control participants met the criteria.
“The increased prevalence of arterial hypertension in ART participants is what is most concerning,” notes senior study investigator Emrush Rexhaj, M.D., director of Arterial Hypertension and Altitude Medicine at Inselspital, University Hospital in Bern, Switzerland. “There is growing evidence that ART alters the blood vessels in children, but the long-term consequences were not known. We now know that this places ART children at six times higher rate of hypertension than children conceived naturally.”
Fascinatingly, the Swiss researchers also studied these participants five years before this study and found that the arterial blood pressure between ART and control children was not different.
“It only took five years for differences in arterial blood pressure to show,” Dr. Rexhaj remarks. “This is a rapidly growing population and apparently healthy children are showing serious signs of concern for early cardiovascular risk, especially when it comes to arterial hypertension.”
In an accompanying editorial, Larry Weinrauch, M.D., a cardiologist at Mount Auburn Hospital, who was not directly involved in the research, explains that the study's small cohort may understate the importance of this problem for ART adolescents, especially since multiple birth pregnancies and maternal risk factors (such as eclampsia, chronic hypertension, and diabetes) were excluded from the study.
“Early study, detection, and treatment of ART-conceived individuals may be the appropriate course of preventative action,” Dr. Weinrauch concludes. “We need to be vigilant in the development of elevated blood pressure among children conceived through ART to implement early lifestyle-based modifications and, if necessary, pharmacotherapy.”