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Anthropometric outcomes at 12 years after fresh versus frozen embryo transfer compared with natural conception
Kensuke Akitsu1, Keiko Ueno1, Masanori Ono2
1Department of Obstetrics and Gynecology, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku, Tokyo 160-0023, Japan.
Insights
Frozen-thawed embryo transfer (FET) did not lead to lasting differences in body size or overweight risk by age 12 compared to fresh embryo transfer (FreET) or natural conception. These findings suggest assisted reproductive technology does not impact long-term child obesity risk.
Area of Science:
- Reproductive Medicine
- Pediatric Endocrinology
- Public Health
Background:
- Assisted reproductive technology (ART) methods like frozen-thawed embryo transfer (FET) are associated with increased birth size.
- The long-term implications of this birth size difference on child development and health are not fully understood.
Purpose of the Study:
- To determine if the elevated birth size observed in children conceived via FET persists into adolescence.
- To compare anthropometric measurements and overweight/obesity risk at 12 years of age among children conceived via FET, fresh embryo transfer (FreET), and natural conception.
Main Methods:
- A multicenter prospective cohort study followed singleton children born between 2008-2009 in Japan.
- Children conceived via ART (FreET, FET) were compared to naturally conceived children from infertile couples (non-ART).
- Overweight and obesity were defined using International Obesity Task Force criteria; analyses adjusted for multiple covariates.
Main Results:
- At 12 years, no significant differences in mean weight, height, or BMI were found among the FreET, FET, and non-ART groups.
- Logistic regression revealed no significant differences in the odds ratios for overweight and obesity across the three conception groups.
- Large for gestational age (LGA) at birth was an independent predictor of larger body size and overweight status in boys.
Conclusions:
- The increased birth size associated with FET does not appear to persist into early adolescence.
- Body size and overweight risk at age 12 are comparable across FET, FreET, and non-ART conception groups.
- Further long-term follow-up is recommended to monitor developmental trajectories through adolescence.
Objective:
To investigate whether the increased birth size linked to frozen-thawed embryo transfer (FET) compared with fresh embryo transfer (FreET) and natural conception persists at 12 years of age.
Methods:
This multicenter prospective cohort study included singleton children born between 2008 and 2009 at 23 JISART-affiliated facilities in Japan. Children conceived via assisted reproductive technology (ART) (FreET and FET) were compared with those conceived naturally by couples who are infertile without ART. Overweight and obesity were defined according to the International Obesity Task Force criteria (overweight: body mass index [BMI] ≥ 23, obesity: BMI ≥ 27). Analyses were performed using analysis of covariance and multiple regression, adjusting for gestational age, maternal age, parity, small/large for gestational age (SGA/LGA), parental body size, education, and infertility duration. Logistic regression was used to assess the risk of overweight/obesity.
Results:
Of 6,434 children initially contacted, 3,002 eligible singletons (1,115 FreET, 1,341 FET, and 546 non-ART) were included in the birth cohort, with 671 (331 boys, 340 girls) finally enrolled. The adjusted mean weight, height, and BMI did not differ among the FreET, FET, and non-ART groups. The odds ratios for overweight and obesity also showed no significant group differences. Parental body size was associated with child anthropometry, and LGA at birth independently predicted a larger body size and being overweight in boys.
Conclusions:
At 12 years, body size and overweight risk were comparable among the three conception groups (FreET, FET, and non-ART groups). We found no statistical evidence that the FET-associated increase in birth size persisted into early adolescence. Continued follow-up during adolescence is warranted.
