Abstract
PURPOSE: This study aimed to assess whether assisted reproductive technology alters DNA methylation levels at the H19 promoter and H19 imprinting control element (ICE) in fetal tissues obtained after multifetal pregnancy reduction. METHODS: Fetal tissues from multiple pregnancies were obtained, including fresh and frozen-thawed embryos: nine from conventional in vitro fertilization (c-IVF), four from intracytoplasmic sperm injection (ICSI), ten from cryopreserved IVF embryos (cryo-IVF), and six from cryopreserved ICSI (cryo-ICSI) embryos. Next-generation sequencing-based bisulfite PCR was used to determine the DNA methylation status of three CpG islands (H19-1, H19-2, and H19-3) in the H19 promoter and H19 ICE. The primary outcome was H19-1 DNA methylation status, whereas secondary outcomes assessed H19-2, H19-3, and ICE methylation. RESULTS: The ICSI (β = -3.189, 95% CI = -5.034 to -1.345, p = 0.0026), cryo-IVF (β = -2.150, 95% CI = -3.706 to -0.593, p = 0.0129), and cryo-ICSI (β = -2.238, 95% CI = -3.817 to -0.659, p = 0.0110) groups exhibited significantly lower methylation levels in the primary outcome H19-1 region than the c-IVF group after adjustment. For the secondary outcome H19-2 region, significant decreases were observed in the cryo-IVF (β = -2.132, 95% CI = -4.071 to -0.192, p = 0.0425) and cryo-ICSI groups (β = -2.598, 95% CI = -4.566 to -0.630, p = 0.0168). CONCLUSIONS: These findings further indicate that embryo cryopreservation and potentially ICSI can lower the methylation level of the H19 promoter, advocating for careful use of these techniques when necessary.