Study design and patients
This study retrospectively collected
and evaluated the clinical data of 8903 patients after FET at the Center
for Reproductive Medicine, Cheeloo College of Medicine, Shandong
University, who were patients between January 2017 and October 2019. All
women were between the ages of 20 to 40 years with a body mass index
(BMI) of no more than 35 kg/m2, who underwent their
first FET during their first in vitrofertilization/intracytoplasmic sperm injection cycle at our centre.
Women were excluded from this study if they (i) underwent frozen-thawed
oocyte cycle or preimplantation genetic testing cycles, (ii) were
diagnosed with premature ovarian insufficiency or a decreased ovarian
reserve, (iii) had a history of unilateral oophorectomy, recurrent
spontaneous abortion or severe intrauterine adhesion, (iv) had medical
conditions that contraindicated assisted reproductive technology or
pregnancy, and (v) were diagnosed with hypertension, diabetes, abnormal
renal function, uterine malformation or abnormal parental karyotypes.
This study was approved by the Ethics Committee of the Center for
Reproductive Medicine, Cheeloo College of Medicine, Shandong University
(2021-25).
All women were assigned to either PCOS or control groups. A diagnosis of
PCOS was based on Rotterdam diagnostic criteria and if at least two of
the following criteria were present: HA (hyperandrogenemia, defined as
total testosterone levels above 48.1 ng/dL, and hirsutism with a total
score ≥8 according to the Ferryman–Gallwey score); OA (defined as a
delay of >35 days or < eight spontaneous
hemorrhagic episodes/years); PCO (defined as ≥12 small follicles
measuring 2–9 mm in at least one ovary or ovarian volume ≥10
cm3)15. Patients with PCOS were
categorised into four phenotype groups according to Rotterdam criteria
as follows16: phenotype A: HA+OA+PCO; phenotype B:
HA+OA; phenotype C: HA+PCO; and phenotype D: OA+PCO.