Babies conceived via IVF are SIX TIMES more likely to have high blood pressure as teenagers (?)

As the father of an adult son conceived via IVF, I have some personal interest in this study.  On looking at it in detail, however, I doubt that the results are much cause for concern.  The "sample" size is small, there was apparently no attempt at random sampling and the average differences found are very slight.

Additionally, I cannot see that they have excluded the effects observed as being due to differences in the mothers rather than differences in the method of conception.  The authors claim to have controlled for differences in the mothers but it is not clear to me how to do that.  Mothers who have to resort to IVF would usually have subtle health differences that could have non-obvious effects.  The cause of infertility is quite often rather mysterious but it is there.

And the father cannot be omitted from consideration either. It can often be the father who is infertile (has a low sperm count or deficient sperm motility) and that could have complex ramifications. The father may have broader health problems that are passed on genetically. I presume the authors were careful enough to leave out conceptions due to ICSI, which is a whole different ballgame (no pun intended).

Those objections do however have the character of denying that any research into the method of conception is possible and I do not want to claim that so let us look again at the other problems in the study.  The sample size is not impossibly small but it very much at the low end of what we expect in delivering stable results.  And that doubt is sharpened when we look at the average differences in BP. 120/71, compared to 116/69, is a trivial difference and founding it on a small sample  makes it a trivial finding.

And the criterion for high blood pressure is very severe: more than 130/80.  In normal clinical practice that would count as being within the normal range.

And the lack of random sampling in assembling the study population is a very large lacuna.  Unless you have some evidence that your sample is representative you cannot validly generalize from it.  Hoping or assuming that it is representative reduces the study to a work of faith, not a work of science

So the study is interesting but far from conclusive.  I append the journal abstract

Thousands of children born each year by IVF could be at risk of serious heart problems in later life, a study suggests.

Scientists found signs of 'premature vascular aging' in children as young as 11 who had been conceived as a result of fertility treatment.

And by the age of 16 IVF children were six times more likely to have high blood pressure - a major risk factor for heart attacks and strokes.

The scientists believe how embryos are fertilised and manipulated before they are implanted into a woman's uterus may cause small genetic changes that affect a baby's heart and circulatory system.

They warn that the soaring use of IVF 'may have come at a price' for many children, who could suffer cardiovascular disease as a result.

Children conceived via IVF have higher blood pressure readings

Researchers from University Hospital in Bern, Switzerland, tracked 54 seemingly healthy children who had been born via IVF, and compared them to 43 children born naturally.

They found at age 11 and 12 the IVF children had a 25 per cent narrower brachial artery - the major blood vessel in the arm - and their arteries had thicker walls.

The team then tracked the children for five years. At the age of 16 and 17 the IVF children were far more likely to have developed high blood pressure. They had an average blood pressure of 120/71, compared to 116/69 for the teenagers who had been conceived naturally.

Crucially, eight of those conceived via IVF had developed 'hypertension' - the medical term for high blood pressure, involving a reading of more than 130/80. Only one of the teenagers conceived naturally had hypertension.

The study bolsters the results of previous research which found mice born to IVF had heart problems.


Association of Assisted Reproductive Technologies With Arterial Hypertension During Adolescence

Théo A.Meister MD et al.


Background: Assisted reproductive technologies (ART) have been shown to induce premature vascular aging in apparently healthy children. In mice, ART-induced premature vascular aging evolves into arterial hypertension. Given the young age of the human ART group, long-term sequelae of ART-induced alterations of the cardiovascular phenotype are unknown.

Objectives: This study hypothesized that vascular alterations persist in adolescents and young adults conceived by ART and that arterial hypertension possibly represents the first detectable clinically relevant endpoint in this group.

Methods: Five years after the initial assessment, the study investigators reassessed vascular function and performed 24-h ambulatory blood pressure (BP) monitoring (ABPM) in 54 young, apparently healthy participants conceived through ART and 43 age- and sex-matched controls.

Results: Premature vascular aging persisted in ART-conceived subjects, as evidenced by a roughly 25% impairment of flow-mediated dilation of the brachial artery (p < 0.001) and increased pulse-wave velocity and carotid intima-media thickness. Most importantly, ABPM values (systolic BP, 119.8 ± 9.1 mm Hg vs. 115.7 ± 7.0 mm Hg, p = 0.03; diastolic BP, 71.4 ± 6.1 mm Hg vs. 69.1 ± 4.2 mm Hg, p = 0.02 ART vs. control) and BP variability were markedly higher in ART-conceived subjects than in control subjects. Eight of the 52 ART participants, but only 1 of the 43 control participants (p = 0.041 ART vs. controls) fulfilled ABPM criteria of arterial hypertension (>130/80 mm Hg and/or >95th percentile).

Conclusions: ART-induced premature vascular aging persists in apparently healthy adolescents and young adults without any other detectable classical cardiovascular risk factors and progresses to arterial hypertension. (Vascular Dysfunction in Offspring of Assisted Reproduction Technologies; NCT00837642.)
Central Illustratio

Journal of the American College of Cardiology, Volume 72, Issue 11, 11 September 2018, Pages 1267-1274

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