Clinical outcomes with transfer of blastocyst or cleavage stage embryos: high order pregnancies, newborn weights and sex ratios.

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Objective: We have previously reported our preliminary clinical experience with the culture and transfer of blastocyst stage embryos. Here, we report results of a retrospective analysis compiling our clinical outcome experience for now two years (1999–2000 period). Design: Retrospective analysis. Materials/Methods: In a total of 599 consecutive unselected cycles in which couples were given the opportunity to have extended culture, implantation rates (gestational sacs/embryos transferred) were 16.5% (182/1100) after day 3 embryo transfers (D3 ET) and 27.2% (157/578) after blastocyst transfers (D5,6 ET), (P < 0.0001). The mean number of embryos transferred was 3.2 ± 0.9 vs. 2.3 ± 0.6 for D3 ET and D5,6 ET, respectively (P < 0.0001). Results: Outcome measures for both groups are shown in the table below. The overall incidence of multiple pregnancy (defined as two or more gestational sacs) is not decreased with D5,6 ET; however, a significant reduction in the frequency of triplet pregnancies is observed with D5,6 ET (P < 0.01). At the time of writing 182 babies have been born. The sex ratio (males:females) in babies from D3 ET (49:51, n = 100) was not different from that of babies from D5,6 ET (47:35, n = 82), (P = 0.3). Likewise, no differences in birth weights were noted for male or female babies born after the transfer of blastocysts vs. cleavage stage embryos (male babies: 2568.5 ± 884.5 grams vs. 2574.2 ± 779.6 grams for D5,6 ET and D3 ET, respectively, P = 0.9; female babies: 2789.6 ± 720.0 grams vs. 2565.7 ± 873.2 grams for D5,6 ET and D3 ET, respectively, P = 0.2). Clinical outcomes after transfer of Day 3 embryos or Blastocyst stage embryos. Tabled 1ParameterDay 3 ET (No. and %)Blastocyst ET (No. and %)P value (Fisher’s exact test)Chemical pregnancies(Positive HCG’s)149/343 (43.4)123/256 (48.0)n.s.Clinical pregnancies (gestational sacs)118/343 (34.4)108/256 (42.2)0.06Singletons68/118 (57.6)63/108 (58.3)n.s.Overall frequency of multiples50/118 (42.4)45/108 (41.7)n.s.Twins37/118 (31.3)42/108 (38.8)n.s.Triplets12/118 (10.2)2/108 (1.9)0.01Quadruplets1/118 (0.8)1/108 (0.9)n.s.Monozygotic twins3/118 (2.5)1/108 (0.9)n.s. Open table in a new tab Conclusions: The high rate of twins with D5,6 ET (38.8%) warrants evaluation of single blastocyst transfers.