Pregnancy and neonatal outcomes of small follicle–derived blastocyst transfer in modified natural cycle in vitro fertilization

The live birth and major anomaly ratios of small follicle– derived blastocyst transfers were the same as those of large (dominant) follicle–derived blastocyst transfers in a modified natural cycle in vitro fertilization.

Volume 111, Issue 4, Pages 747–752


Shokichi Teramoto, M.D., Hisao Osada, M.D., Ph.D., Yasunori Sato, Ph.D., Makio Shozu, M.D., Ph.D.



To compare the efficacy and safety of blastocyst transfer derived from small follicles (SF; ≤10 mm) and large follicles (LF; ≥11 mm).


Retrospective cohort study.


Private clinic.


Patients (n = 1,072) 30–40 years old who underwent blastocyst transfer (BT; n = 1,247) between January 2012 and December 2014.


Oocytes retrieved during a modified natural cycle from both LF and SF were fertilized by a conventional method or intracytoplasmic sperm injection. The blastocysts were frozen, thawed, and transferred one by one in the following spontaneous ovulatory cycles or hormone replacement cycles.

Main Outcome Measure(s)

BT resulted in live births and major congenital anomalies.


SF-derived BTs (n = 597) yielded 55 chemical abortions (9.2%), 73 clinical abortions (12.2%), and 261 live births (43.8%), whereas LF-derived BTs (n = 650) yielded 71 chemical abortions (10.9%), 73 clinical abortions (11.2%), and 311 live births (47.9%). These incidences were not statistically different between SF- and LF-derived BTs. The incidence of abnormal karyotypes was also not statistically different between SF- and LF-derived spontaneous abortions (71% [39/55] vs. 72% [40/55], respectively). The incidence of major congenital anomalies in neonates did not differ between SF- and LF-derived pregnancies (1.5% and 1.3%, respectively; relative risk = 1.10, 95% confidence interval [0.55–3.21]).


SF-derived BT is as efficacious and safe as LF-derived BT.

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