Comparison of natural cycles versus hormone replacement
treatment cycles for endometrial preparation prior to frozen-thawed
embryo transfer: a retrospective cohort study from 9733 cycles
Xitong Liu,a Hui Wang,a He
Cai,a Juanzi Shi,a
a The Assisted Reproduction Center, Northwest women’s
and Children’s Hospital, Xi’an, China
Correspondence: Juanzi Shi, The Assisted Reproduction Center,
Northwest women’s and Children’s Hospital, Xi’an, China.
Email: shijuanzi123@163.com
Running title: Outcome of NC vs HRT
Objective To compare the effectiveness of natural cycles (NC)
and artificial cycles (AC) in women undergoing frozen-thawed embryo
transfer (FET) after in vitro fertilization (IVF).
Design Retrospective cohort study.
Setting Public fertility center in China.
Population We studied 9733 women undergoing the first cycle of
FET over a 3-year period (June 2014 - December 2017). All women were
followed-up until one year after embryo transfer.
Methods The type of endometrial preparation was determined by
the treating physician’s preference, based on patients’ characteristics.
Women with regular ovulation were allocated to natural cycles (n=1676),
while patients who were reluctant to frequently monitoring or living far
from the hospital were allocated to artificial cycles (n=8057). A
logistic regression model was used to assess the association between
endometrial preparation and clinical outcomes while adjusting for
potential confounders.
Main outcome measures Live-birth rate was primary outcome while
miscarriage rate, clinical pregnancy rate, preterm birth rate, and
ectopic pregnancy rate were secondary outcomes.
R esults In the
adjusted model, type of endometrial preparation did not affect live
birth (OR, 0.89; 95%CI, 0.79-1.01), clinical pregnancy (OR, 0.96;
95%CI, 0.85-1.09), preterm birth (OR, 1.09; 95%CI, 0.90-1.33) and
ectopic pregnancy (OR, 0.77; 95%CI, 0.36-1.61), while AC significantly
increased the miscarriage rate (OR, 1.38; 95%CI, 1.11-1.73, P=0.004).
Conclusion In women undergoing FET, natural cycles and
artificial cycles resulted in comparable live birth rate while
miscarriage rate was higher in artificial cycles.
Keywords frozen-thawed embryo transfer, natural cycles,
artificial cycles, miscarriage rate, live birth rate.
Tweetable abstract In women undergoing FET, natural cycles and
artificial cycles resulted in comparable live birth rate while
miscarriage rate was higher in artificial cycles.