{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,30]],"date-time":"2026-10-30T16:40:31Z","timestamp":1793378431558,"version":"4.5.0"},"reference-count":38,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,7,22]],"date-time":"2021-07-22T00:00:00Z","timestamp":1626912000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:p><jats:bold>Background:<\/jats:bold> Endometrial preparation is essential in frozen-thawed embryo transfer (FET) cycles. Recent studies suggested that different endometrial preparation methods may influence obstetrical complications. However, the association between hormone replacement therapy (HRT) and ovarian stimulation (OS) FET endometrial preparation and obstetrical complications remains unknown.<\/jats:p><jats:p><jats:bold>Methods:<\/jats:bold> This retrospective cohort study included a total of 79,662 confirmed embryo transfer cycles during the period from January 2003 to December 2019. After exclusion, the remaining cases were categorized into an ovarian stimulation FET group (OS FET group, <jats:italic>n<\/jats:italic> = 29,121) and a hormone replacement therapy FET group (HRT FET group, <jats:italic>n<\/jats:italic> = 26,776) and subjected to the analyses. The primary outcome was the rate of obstetrical complications included placenta previa, placenta abruption, hypertensive disorders of pregnancy (HDP), placenta accreta, gestational diabetes mellitus (GDM), preterm premature rupture of the membrane (pPROM). The secondary outcome was pregnancy outcomes such as live birth rate, birth weight, pre-term and post-term delivery and cesarean sections. In order to minimize the bias, 10 pregnancy-related factors were adjusted in multiple logistic regression analysis.<\/jats:p><jats:p><jats:bold>Results:<\/jats:bold> Placenta previa (0.6 vs. 1.2%, <jats:italic>P<\/jats:italic> &amp;lt; 0.001) and HDP (3.5 vs. 5.3%, <jats:italic>P<\/jats:italic> &amp;lt; 0.001) were found lower in the OS FET than HRT FET group. Cesarean section was observed lower in the OS than HRT group (76.3 vs. 84.3%, <jats:italic>P<\/jats:italic> &amp;lt; 0.001). After adjustment for 10 important pregnancy-related confounding factors, we found that the risk of placenta previa (aOR 0.54, 95% CI 0.39\u20130.73) and HDP (aOR 0.65, 95% CI 0.57\u20130.75) and cesarean section (aOR 0.61, 95% CI 0.57\u20130.66) were still significantly reduced in the OS than HRT group. Furthermore, live birth rates were higher (80.0 vs. 76.0%, <jats:italic>P<\/jats:italic> &amp;lt; 0.001), and the miscarriage rate was lower (17.7 vs. 21.3%, <jats:italic>P<\/jats:italic> &amp;lt; 0.001) for pregnancies conceived with OS FET than with HRT FET. And the average birth weight was lower in the OS group compared to HRT group (2982.3 \u00b1 636.4 vs. 3025.0 \u00b1 659.0, <jats:italic>P<\/jats:italic> &amp;lt; 0.001), as well as the small-for-gestational age (SGA) was higher (8.7 vs. 7.2%, <jats:italic>P<\/jats:italic> &amp;lt; 0.001) and the large-for-gestational age (LGA) was lower (7.2 vs. 8.6%, <jats:italic>P<\/jats:italic> &amp;lt; 0.001) in the OS group than in the HRT group.<\/jats:p><jats:p><jats:bold>Conclusions:<\/jats:bold> The risks of placenta previa and HDP were lower in patients conceiving after OS FET than in those after HRT FET. Further prospective studies are required to further clarify the mechanism underlying the association between endometrium preparation and obstetrical complications.<\/jats:p>","DOI":"10.3389\/fmed.2021.646220","type":"journal-article","created":{"date-parts":[[2021,7,22]],"date-time":"2021-07-22T10:39:25Z","timestamp":1626950365000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":17,"title":["Risks of Placenta Previa and Hypertensive Disorders of Pregnancy Are Associated With Endometrial Preparation Methods in Frozen-Thawed Embryo Transfers"],"prefix":"10.3389","volume":"8","author":[{"given":"Yu","family":"Tao","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanping","family":"Kuang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ningling","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2021,7,22]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"1567","DOI":"10.1093\/humrep\/dez079","article-title":"Endometrial preparation methods for frozen-thawed embryo transfer are associated with altered risks of hypertensive disorders of pregnancy, placenta accreta, and gestational diabetes mellitus","volume":"34","author":"Saito","year":"2019","journal-title":"Hum Reprod."},{"key":"B2","doi-asserted-by":"publisher","first-page":"1703","DOI":"10.1016\/j.fertnstert.2016.08.047","article-title":"Obstetric and perinatal outcomes after either fresh or thawed frozen embryo transfer: an analysis of 112,432 singleton pregnancies recorded in the Human Fertilisation and Embryology Authority anonymized dataset","volume":"106","author":"Maheshwari","year":"2016","journal-title":"Fertil Steril"},{"key":"B3","doi-asserted-by":"publisher","first-page":"m2519","DOI":"10.1136\/bmj.m2519","article-title":"Freeze-all versus fresh blastocyst transfer strategy during in vitro fertilisation in women with regular menstrual cycles: multicentre randomised controlled trial","volume":"370","author":"Stormlund","year":"2020","journal-title":"BMJ"},{"key":"B4","doi-asserted-by":"publisher","first-page":"2808","DOI":"10.1093\/humrep\/deaa226","article-title":"The freeze-all strategy versus agonist triggering with low-dose hCG for luteal phase support in IVF\/ICSI for high responders: a randomized controlled trial","volume":"35","author":"Santos-Ribeiro","year":"2020","journal-title":"Hum Reprod"},{"key":"B5","doi-asserted-by":"publisher","first-page":"35","DOI":"10.1093\/humupd\/dmx031","article-title":"Is frozen embryo transfer better for mothers and babies? 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