A large international study looking at the effects of fertility treatment has found no robust difference in blood pressure, heart rate, lipids, and glucose measurements between children conceived naturally and those conceived using assisted reproductive technologies.
Use of assisted reproductive technology (ART) has "risen rapidly" in developed countries over recent decades, leading to more than 8 million births worldwide, said the authors of a new study, published in the European Heart Journal.
They explained that the number of ART births is "expected to continue to rise", but that there persists a disquietude that the use of ART may cause "adverse cardiovascular and metabolic health outcomes in the offspring".
They pointed out that previous studies investigating this concern were limited by small sample size, short follow-up, and unsatisfactory comparison groups.
No Robust Differences
The researchers, led by the University of Bristol, sought to examine associations of ART conception versus natural conception with offspring cardiometabolic health outcomes, and whether these differed with age.
For their study, they performed a meta-analysis of a total of 14 cohorts – two cohorts each from the UK, the Netherlands, Italy, and Australia, and one cohort each from Ireland, France, Portugal, Greece, Norway, and Singapore. The cohorts included 35,938 offspring, of which 654 were conceived using ART, with a mean age range of 13 months to 27.4 years, but was under 10 years in 11 of the 14 cohorts.
The data sample included 8600 children from Bristol’s Children of the 90s study. Also known as the Avon Longitudinal Study of Parents and Children (ALSPAC), and based at the University of Bristol, the Children of the 90s study is a long-term health research project that enrolled more than 14,000 pregnant women in 1991 and 1992 and has followed the health and development of the parents, their children, and now their grandchildren, in detail ever since.
Dr Ahmed Elhakeem, epidemiology research fellow, Bristol Medical School, University of Bristol, and lead study author, highlighted that the new study was "the largest study of its kind, and could not be conducted without data from studies such as Children of the 90s".
Deborah Lawlor, professor of epidemiology, MRC investigator, British Heart Foundation chair, and senior author from Bristol Medical School, reiterated: "This important research is only possible through large scale international collaboration and longitudinal health studies, where participants contribute health data throughout their entire lives."
The authors found that blood pressure, heart rate, and glucose levels were "similar" in children conceived using ART and their naturally-conceived peers. In addition, they also identified that those who were conceived by ART had slightly higher cholesterol levels in childhood, which "did not persist to adulthood", and some indication of "slightly higher blood pressure in adulthood".
Results in singleton births were consistent with results in all participants, with both singletons and multiple births included, they said.
"Overall, our findings should be deemed largely reassuring to people conceived by ART," the authors said.
Parents Offered Reassurance
"Parents conceiving or hoping to conceive through assisted reproductive technology and their offspring should be reassured that cardiometabolic health appears to be comparable in ART-conceived and naturally conceived children," said Dr Elhakeem.
Commenting on the study’s findings Peter Thompson, chief executive of the Human Fertilisation and Embryology Authority (HFEA), said: "Each year around 60,000 patients use fertility services in the UK in the hope of one day having a family of their own. Those patients should be reassured by this study which shows that the heart health of children born from assisted reproduction technologies, like IVF, are no different from children conceived naturally."
"Studies with longer follow-up would now be beneficial to examine how results might change across adulthood," Dr Elhakeem pointed out.
The authors said such studies should examine associations of ART with cardiometabolic health – including the risks of hypertension, dyslipidaemia, and preclinical and clinical cardiovascular disease – across adulthood and should also "investigate mechanisms that might link ART to subsequent outcomes, if evidence does emerge in later adulthood", they said.
"Future research on epigenetics, metabolomics, and cardiovascular and arterial phenotypes may provide insight into possible underlying mechanisms," they added.