Blood pressure and lipid profiles favorable in children born after ART with frozen embryo transfer; Study
More than 10 million children have been born after the use of assisted reproductive technology (ART). Especially the use of frozen, and later on thawed, embryos has been increasing steadily during the last decade. The health of the children born after ART is of utmost interest to the parents and to society. Studies have shown that children born after the use of frozen/thawed embryos are born with a higher birthweight compared with children conceived naturally or after the use of fresh embryos. However, the potential long-term implications of this elevated birthweight remain insufficiently explored.
This study by Asserhøj et al was part of the cohort study ‘Health in Childhood following Assisted Reproductive Technology’ (HiCART), which included 606 singletons (292 boys) born between December 2009 and December 2013: 200 children were conceived after FET; 203 children were conceived after fresh-ET; and 203 children were conceived naturally and matched for birth year and sex. The study period lasted from January 2019 to September 2021. The included children were 7–10 years of age at examination and underwent a clinical examination with anthropometric measurements, pubertal staging, and BP measurement. Additionally, a fasting blood sample was collected and analysed for cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL), and triglycerides. Systolic and diastolic BP were converted to standard deviation scores (SDS) using an appropriate reference and accounting for height (SDS) of the child. The three study groups were compared pairwise using a univariate linear regression model. Mean differences were adjusted for confounders using multiple linear regression analyses.
Girls and boys conceived after FET had significantly higher birthweight (SDS) compared with naturally conceived peers (mean difference: girls: 0.35, 95% CI (0.06–0.64), boys: 0.35, 95% CI (0.03–0.68)).
Girls conceived after FET had significantly higher systolic BP (SDS) and heart rate compared with girls conceived after fresh-ET (adjusted mean difference: systolic BP (SDS): 0.25 SDS, 95% CI (0.03–0.47), heart rate: 4.53, 95% CI (0.94–8.13)).
Regarding lipid profile, no significant differences were found between the three groups of girls. For the boys, no significant differences were found for BP and heart rate.
Lipid profiles were more favourable in boys born after FET compared with both boys conceived after fresh-ET and NC. All outcomes were adjusted for parity, maternal BMI at early pregnancy, smoking during pregnancy, educational level, birthweight, breastfeeding, child age at examination, and onset of puberty.
In an analysis of BP, heart rate, and lipid profile in 606 children born after FET, fresh-ET, and NC, and stratified on sex, authors found significantly higher SBP, SBP (SDS), and heart rate in girls born after FET compared with girls born after fresh-ET. Boys born after FET had a more favourable lipid profile compared with boys born after fresh-ET and NC.
In this study where a large cohort of children born after FET, fresh-ET, and NC has been investigated, authors observed elevated SBP, SBP (SDS), and heart rate among girls conceived after FET when compared with girls conceived after fresh-ET. These differences persisted in sensitivity analyses restricted to pre-pubertal girls. Notably, these disparities were not found in boys. Further, boys born after FET exhibited more favourable lipid profiles compared with boys born after fresh-ET and NC. These findings suggest that girls and boys may display different susceptibility to intrauterine perturbances affecting the cardiovascular system in childhood and this emphasizes the need for further long-term follow-up studies on children born after ART stratified on sex.
Source: Asserhøj et al.; Human Reproduction Open, 2024, 2024(2), hoae016 https://doi.org/10.1093/hropen/hoae016
