Perinatal morbidity after in vitro fertilization is lower with frozen embryo transfer

Abstract

Objective To study the association of perinatal outcome and IVF transfer type in a group of infertility patients with standardized treatment and similar prognosis. Design Retrospective cohort study. Setting University-based infertility center, January 1998 to June 2006. Patient(s) Two hundred eighteen IVF pregnancies after fresh embryo transfer (ET); 122 IVF pregnancies after frozen ET. Intervention(s) Assessment of perinatal outcome in fresh versus frozen ET pregnancies. Main Outcome Measure(s) Pregnancy outcomes after fresh versus frozen embryo transfer (ET). Primary outcome was a composite of three events: preterm delivery, intrauterine growth restriction, or low birth weight. Secondary outcomes were subtypes of pregnancy loss. Associations were assessed using multivariate logistic regression. Result(s) The final sample included 340 pregnancies: 218 fresh and 122 frozen ETs. Singleton pregnancy was less likely after transfer of fresh embryos (odds ratio [OR] 0.39, 95% confidence interval [CI] 0.23–0.67), and pregnancies after fresh ET were more likely to end in first-trimester loss (OR 1.82, 95% CI 1.05–3.13). Composite adverse outcome after transfer of fresh (44.0%) versus frozen (32.6%) embryos was higher (OR 1.52, 95% CI 0.90–2.56) and was strongly associated with twin gestation (OR 23.82, 95% CI 11.16–50.82). Conclusion(s) Perinatal morbidity is higher in IVF pregnancies conceived after a fresh ET compared with a frozen ET. Although some differences are related to conception with twin gestations, these findings suggest that adverse outcomes may be related to differences in IVF procedures.

Risk of adverse pregnancy and perinatal outcomes after high technology infertility treatment: a comprehensive systematic review

“…In addition, a bias due to difference in prognosis between populations cannot be excluded. In fact, although the risk of pregnancy complications was higher in the paired comparison of the same patient who conceived after fresh vs. subsequent frozen-thawed ET (including donor cycles) [82], it is likely that the frozen embryo populations are more likely composed of the better prognosis patients. Similarly, also the selection bias due to the physical effects of freezing and thawing on the worse embryos cannot be excluded.…”

Which one has a better obstetric and perinatal outcome in singleton pregnancy, IVF/ICSI or FET?: a systematic review and meta-analysis

“…Other studies suggested that ovarian hyper-stimulation during fresh cycles change angiogenesis of endometrium and embryo imbed [22–24]. …”

Why we should transfer frozen instead of fresh embryos: the translational rationale

“…So a question remains: What happens to the developing embryo that does successfully implant in an endometrium exposed to the abnormal hormonal milieu following superovulation? Recent epidemiologic evidence suggests that the peri-implantation environment created by superovulation may be contributing to at least some of the adverse perinatal outcomes following ART, and that these effects can be minimized by transferring embryos in a subsequent frozen embryo transfer cycle (4, 5, 15–23). A large retrospective study by Kalra et al using the Society for Assisted Reproductive Technologies (SART) database demonstrated a significant increase in low-birthweight (LBW) singleton infants (<2,500 g) born after fresh embryo transfers compared with infants born after frozen embryo transfer cycles (odds ratio [OR] 1.46, 95% confidence interval [CI] 1.34–1.58) (5).…”