Predictors of Perfect Implantation in Double Embryo Transfer With In Vitro Fertilization [157].

INTRODUCTION AND BACKGROUND: Approximately half of in vitro fertilization (IVF) cycles are double embryo transfers, often resulting in multiple gestations, which increases maternal and neonatal morbidity. We assessed trends and predictors of "perfect implantation" in double embryo transfer (both embryos implant) to further identify candidates for elective single embryo transfer.

METHODS: We analyzed 1,793,067 fresh, autologous cycles reported to the National Assisted Reproductive Technology Surveillance System from 2000 to 2012. We calculated trends of perfect implantation in double embryo transfer, identified as cycles with number of hearts on 6-week ultrasonography equal to or greater than number of embryos transferred. Adjusted risk ratios (RRs) for perfect implantation were estimated using log binomial models, adjusted for demographic and clinical characteristics, after stratifying by prognosis. Favorable prognosis was defined as first-time IVF with supernumerary embryo(s). Average prognosis was defined as first-time IVF without supernumerary embryos, prior unsuccessful IVF with supernumerary embryo(s), prior IVF with previous birth(s) resulting from IVF, or natural conception.

RESULTS: During 2000-2012, rates of perfect implantation with double embryo transfer increased from 13.4% to 18.1% (P for trend <.001). Perfect implantation was positively associated with blastocyst (compared with cleavage) transfer in favorable (adjusted RR 1.58 [1.51-1.65]) and average (adjusted RR 1.67 [1.60-1.75]) prognosis groups and negatively associated with age older than 35 years in both prognosis groups. For average prognosis patients, perfect implantation was associated with retrieving more than 10 oocytes (adjusted RR 1.22 [1.18-1.24]).

CONCLUSION: Regardless of prognosis, patients who are younger than 35 years with blastocyst-stage embryos, and average prognosis patients from whom more than 10 oocytes are retrieved, may be good candidates for elective single embryo transfer, which would reduce multiple gestations and associated complications.