ESPE Abstracts

Background: Children conceived after assisted reproductive technology (ART) with frozen embryo transfer (FET) are more often born large-for-gestational age (LGA) while children born after fresh embryo transfer (fresh-ET) are at risk of being small-for-gestational age (SGA). LGA or SGA children are at increased risk of obesity, diabetes and cardiovascular disease later in life. The long-term cardio-metabolic health of children born after ART is scarcely explored.

Materials and method: The cross-sectional cohort study “Health in Childhood following Assisted Reproductive Technology” (HiCART) includes 606 singletons (292 boys): 200 conceived after FET; 203 conceived after fresh-ET; and 203 naturally conceived (NC) children matched for birth year and sex. They were examined at 7-10 years of age including anthropometric measurements, whole-body dual-energy x-ray absorptiometry (DXA), pubertal staging (Tanner), blood pressure (BP) and a fasting blood sample. Anthropometrics and BP were converted to standard deviation scores (SDS).

Results: In the following the three groups were compared pairwise and data shown in mean (SD). Children conceived after FET had significantly higher birth weight (SDS) (0.20 SDS (1.09)) and children conceived after fresh-ET had lower birth weight (SDS) (-0.22 SDS (1.00)) compared to NC children (-0.16 SDS (1.09)). Pubertal onset in 54 girls (17%) and three boys (1%) was evenly distributed among the groups. No differences in height (SDS), weight (SDS) or BMI (SDS) was found between the groups. A more thorough investigation of body composition showed no differences between the groups regarding waist-to-height ratio (FET: 0.44 (0.04), fresh-ET: 0.43 (0.03), NC 0.44 (0.04)) and fat percentage (DXA) (FET: 28.2% (6.77), fresh-ET: 28.1% (6.50), NC: 28.2% (6.24)). Glucose metabolism was similar in the groups including fasting glucose, C-peptide, HbA1c and insulin resistance (HOMA-IR). Lipid profiles including cholesterol, low-density-lipoprotein and high-density-lipoprotein were also similar. No differences were seen in diastolic BP (SDS) between the groups (FET: 0.46 SDS (0.56), fresh-ET: 0.39 SDS (0.58), NC: 0.49 SDS (0.57)) but surprisingly systolic BP (SDS) was slightly lower in the fresh-ET-group (0.53 SDS (0.67)) compared to both FET (0.70 SDS (0.86 SD)), P=0.03 and NC (0.71 SDS, (0.68)), P=0.01.

Conclusion: The differences in birth weight in children conceived after FET and fresh-ET was as expected but did not translate into differences in anthropometrics, glucose- or lipid profile in childhood. Systolic BP was not increased after FET nor fresh-ET. These findings are reassuring and may add to the knowledge about the safety and long-term consequences of FET and ART in general.