1. Overweight or obesity in children born after assisted reproductive technologies in Denmark: A population-based cohort study.
- Author
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Laugesen, Kristina, Veres, Katalin, Hernandez-Diaz, Sonia, Chiu, Yu-Han, Oberg, Anna Sara, Hsu, John, Rinaudo, Paolo, Spaan, Mandy, van Leeuwen, Flora, and Sørensen, Henrik Toft
- Subjects
REPRODUCTIVE technology ,OVERWEIGHT children ,CHILDHOOD obesity ,INDUCED ovulation ,FERTILIZATION in vitro - Abstract
Background: The association between assisted reproductive technologies (ARTs) and the body mass index (BMI) of children remains controversial. Confounding by morbidity and other factors associated with parental infertility may have biased studies comparing children born after ART with children born after no treatment. We investigated the associations between different fertility treatments and BMI in children at age 5 to 8 years, adjusting for and stratifying by causes of parental infertility. Methods and findings: This Danish cohort study included 327,301 children born between 2007 and 2012 (51% males, median age at follow-up 7 years). Of these, 13,675 were born after ART, 7,728 were born after ovulation induction with or without intrauterine insemination [OI/IUI], and 305,898 were born after no fertility treatments. Using the International Obesity Task Force (IOTF) standards, we defined overweight (BMI ≥ IOTF-25) and obesity (BMI ≥ IOTF-30). We compared children born after ART versus OI/IUI; intracytoplasmic sperm injection (ICSI) versus conventional in vitro fertilization (IVF); and frozen-thawed versus fresh embryo transfer and estimated crude and adjusted prevalences of children with overweight or obesity at age 5 to 8 years, prevalence odds ratios (PORs), and differences in mean BMI z-scores. Adjustment was performed using stabilized inverse probability of treatment weights, including parity, year of conception, parental causes of infertility, age, educational level, comorbidities, maternal country of origin, BMI, and smoking as covariates. The crude prevalence of obesity was 1.9% in children born after ART, 2.0% in those born after OI/IUI, and 2.7% in those born after no fertility treatment. After adjustment, children born after ART and OI/IUI had the same prevalence of being overweight (11%; POR 1.00, 95% confidence interval [CI] 0.91 to 1.11; p = 0.95) or obese (1.9%; POR 1.01, 95% CI 0.79 to 1.29; p = 0.94). Comparison of ICSI with conventional IVF yielded similar pattern (POR 0.95, 95% CI 0.83 to 1.07; p = 0.39 for overweight and POR 1.16, 95% CI 0.84 to 1.61; p = 0.36 for obesity). Obesity was more prevalent after frozen-thawed (2.7%) than fresh embryo transfer (1.8%) (POR 1.54, 95% CI 1.09 to 2.17; p = 0.01). The associations between fertility treatments and BMI were only modestly different in subgroups defined by the cause of infertility. Study limitations include potential residual confounding, restriction to live births, and lack of detailed technical information about the IVF procedures. Conclusions: We found no association with BMI at age 5 to 8 years when comparing ART versus OI/IUI or when comparing ICSI versus conventional IVF. However, use of frozen-thawed embryo transfer was associated with a 1.5-fold increased risk of obesity compared to fresh embryo transfer. Despite an elevated relative risk, the absolute risk difference was low. In a population-based cohort study, Kristina Laugesen and colleagues investigate the associations between different fertility treatments and body mass index in children born after assisted reproductive technologies in Denmark. Author summary: Why was this study done?: The number of children born after in vitro fertilization (IVF) is increasing. Information about long-term health of these children is limited, and the association between IVF and body mass index (BMI) of the children remains controversial. Various procedures, such as type of fertilization and embryo transfer, and underlying causes of infertility may influence associations. What did the researchers do and find?: The researchers used Danish national registries to conduct a cohort study on the association between different fertility treatments and BMI in children at age 5 to 8 years, taking into account underlying causes of infertility. Children born after IVF had similar BMI compared with those born after ovulation induction (with or without intrauterine insemination) and compared with those born after no fertility treatment. Children born after frozen-thawed embryo transfer had higher BMI and higher prevalence of obesity compared with those born after fresh embryo transfer, compared with those born after ovulation induction (with or without intrauterine insemination), and compared with those born after no fertility treatment. Findings were consistent across subgroups defined by underlying cause of infertility. What do these findings mean?: Our study provides reassuring results for couples who seek help to conceive. Reasons behind our findings for frozen-thawed embryo transfer need further investigation. Longer follow-up and assessment of other outcomes related to metabolic health is needed. Study limitations include potential residual confounding, inclusion of live births only, and lack of detailed technical information about the IVF procedures. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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