Study question: Do young adolescents conceived by ICSI display a higher blood pressure than spontaneously conceived (SC) adolescents?
Summary answer: In our study, 14-year-old male and female ICSI teenagers were not found to have increased blood pressure at rest.
What is known and what this paper adds: Only limited data are available regarding the cardiovascular risk of children born after assisted conception and up till now, no data on the cardiovascular health in pubertal children conceived by ICSI have been published. In this study, resting blood pressure and blood pressure response to a psychological stressor were measured in a cohort of 14-year-old teenagers conceived by ICSI and compared the results with those of a group of SC peers.
Design: In this cross-sectional study, resting blood pressure measurements were available from 217 singleton ICSI children (116 boys, 101 girls) and 223 singleton control children born after spontaneous conception (115 boys, 108 girls). Continuous blood pressure measurements, performed during a psychological stress test, were available for only 67 ICSI and 38 SC children.
Participants and setting: The study group comprised adolescents conceived by ICSI predominantly because of male factor infertility and they were part of a previously published cohort followed since birth; controls were a cross-sectional sample of peers born to fertile parents and recruited from comparable schools as those attended by the ICSI teenagers. Response rates were 56% (tested/reached) in the ICSI group and 50% (agreed/eligible) in the SC group, but information regarding health could be obtained in 63 and 72% of the ICSI and SC children, respectively.
Main results and the role of chance: ICSI girls had a comparable resting systolic (109 ± 9 mmHg) and diastolic (64 ± 6 mmHg) blood pressure in comparison with girls in the SC group (111 ± 9 mmHg, P = 0.2 and 66 ± 7 mmHg, P = 0.05), even after adjustment for age and height. After adjustment for current body characteristics, early life and parental background factors, systolic and diastolic blood pressure remained comparable in both groups. In ICSI boys, a slightly lower systolic (113 ± 10 mmHg), but comparable diastolic (64 ± 6 mmHg) resting blood pressure was found in comparison with the SC group (116 ± 9 mmHg; P = 0.04 and 65 ± 5 mmHg; P = 0.1). After adjustment for height and age, systolic and diastolic blood pressure were comparable in both groups (P = 0.7 and P = 0.6). After correction for current body characteristics, early life and parental factors, ICSI and SC boys still had comparable systolic (difference in ICSI versus SC: -1.1 mmHg; 95% CI: -3.8-1.6; P = 0.4) and diastolic (difference in ICSI versus SC: -1.2 mmHg; 95% CI: -3.2-0.7; P = 0.2) blood pressure measurements. In the small subsample of girls and boys with continuous blood pressure readings, the systolic and diastolic blood pressure response to the stress test was not significantly different between the ICSI and SC groups even after taking into account the baseline values.
Bias, confounding and other reasons for caution: Despite the rather low response rate in the ICSI group and the fact that no information on current health status could be obtained from more than a quarter of the eligible comparison group, the non-participating analysis in the ICSI as well in the SC group did not reveal differences between participating and non-participating children regarding clinical characteristics. The negative results for the sub-analysis on blood pressure response to stress should be interpreted with caution, because these data were available for only a small number of children, and the analysis may be underpowered. This result can only rule out a large effect on blood pressure responsiveness to a psychological stressor. Although our sample size appears to be appropriate, our results need confirmation by others and in larger cohorts when more data become available.
Generalizability to other populations: Our results are the first described ever in ICSI offspring, born to parents suffering from predominantly male factor infertility.
Study funding/competing interest(s): This study was supported by research grants from Fonds voor Wetenschappelijk Onderzoek Vlaanderen, Onderzoeksraad Vrije Universiteit Brussel and Wetenschappelijk Fonds Willy Gepts. Unconditional grants from MSD Belgium, Merck International, IBSA Institut Biochimique and Ferring International Center are kindly acknowledged.