ArticleF&S reports2021
The impact of estradiol on pregnancy outcomes in letrozole-stimulated frozen embryo transfer cycles.
Article in F&S reports, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Who cites it
3 citing papers in PubMed, 3 citations in OpenAlex.
- Serum estradiol on the day of final oocyte maturation and outcome of assisted reproduction in women with thyroid autoimmunity.Scientific reports · 2025Article
- Pregnancy and neonatal outcomes of letrozole versus natural cycle frozen embryo transfer of autologous euploid blastocyst.Journal of assisted reproduction and genetics · 2023Article
- Exploring the impact of Ramadan fasting on women's reproductive health: A narrative review.Women's health (London, England)Review
Corrections and comments
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Authors and funding
7 authors at 1 institution in 1 country.
Funding
Abstract
objectiveTo assess the impact of low estradiol (E2) levels in letrozole-stimulated frozen embryo transfer (FET) cycles on pregnancy and neonatal outcomes.
designRetrospective cohort.
settingUniversity-affiliated fertility center. PATIENTS: All patients who underwent letrozole-stimulated FET cycles from January 2017 to April 2020 (n = 217). The "Low E2" group was defined as those with E2 serum levels on the day of trigger <10th percentile level (E2 <91.16 pg/mL, n = 22) and the "Normal E2" group was defined as those with E2 serum levels ≥10th percentile level (E2 ≥91.16 pg/mL, n = 195).
interventionsNone.
main outcome measuresPregnancy outcomes including rates of clinical pregnancy, clinical miscarriage, and live birth. Neonatal outcomes including gestational age at delivery, birth weight, and Apgar score.
resultsThe mean ± SD estradiol level was 66.8 ± 14.8 pg/mL for the "Low E2" group compared with 366.3 ± 322.1 pg/mL for the "Normal E2" group. There were otherwise no substantial differences in cycle characteristics such as endometrial thickness on the day of ovulation trigger and progesterone levels in early pregnancy. The "Low E2" group had a significantly higher clinical miscarriage rate (36.4% vs. 8.8%, adjusted odds ratio 8.06) and lower live birth rate (31.8% vs. 57.9%, adjusted odds ratio 0.28). Neonatal outcomes such as gestational age at delivery, mean birth weight, Apgar scores, and incidence of newborn complications were not clinically different between the groups.
conclusionLow E2 levels were associated with a significantly higher miscarriage rate and lower live birth rate, suggesting that E2 levels in the follicular phase may have an effect on cycle outcomes. Given the rise in use of FET, further studies are needed to confirm our findings and understand the mechanisms.
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