Table 1 Characteristics of studies included in the meta-analysis
Study | Country | Year | Definition of normal BMI | Low BMI | Normal weight | High BMI | Patients | Embryo stage | Autologous or donor oocytes cycle | Ovarian status of the patients | Cycle rank | Endometrial preparation |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Chen et al. [22] | China | 2018 | 18.5–24 | NA | 21.1 ± 1.5 | 26.8 ± 2.3 | Inclusion: Age ≤ 35 years, with PCOS, First IVF/ICSI cycles, GnRH-ant protocol for COH Exclusion: Congenital adrenal hyperplasia, androgen secreting tumors, or Cushing’s syndrome | Both | Autologous | Only PCOS | All | depends on patients' condition |
Insogna et al. [23] | USA | 2017 | 18.5–24.9 | Not specified | Not specified | Not specified | Inclusion: All consecutive FBT cycles Exclusion: Incomplete information cycles, cancelled cycles | Blastocyst | Both | Both | All | HRT after pituitary suppression |
Jin et al. [24] | China | 2019 | 18.5–23.9 | Not specified | Not specified | Not specified | Inclusion: Age < 35 years; tubal factors or primary infertility; poor semen quality; retro grade ejaculation or obstructive azoospermia for ICSI; normal menstrual cycle Exclusion: PCOS; endometriosis; endocrine abnormalities; chromosome polymorphism or chromosome abnormalities; adverse pregnant production history; ovarian dysfunction; ovarian surgery or uterine malformation; donated oocytes | Both | Autologous | Not PCOS | First | depends on patients' condition |
Lin et al. [25] | China | 2019 | 18.5–24.9 | NA | 21.45 ± 1.7 | 28.6 ± 2.1 | Inclusion: PCOS; Age 20–35 years; first FET cycles Exclusion: History of unilateral oophorectomy; abnormalities of the uterus; karyotypic abnormalities; recurrent pregnancy loss; any conditions which precluded the safety of pregnancies or ART | Both | Autologous | Only PCOS | First | HRT or mild stimulation |
Oliva et al. [33] | USA | 2020 | 18.5–24.9 | Not specified | Not specified | NA | Inclusion: Age 20–46 years, all patients with a documented BMI Exclusion: BMI ≥ 25 kg/m2 | Blastocyst | Autologous | Not specified | Not specified | HRT |
Ozgur et al. [26] | Turkey | 2019 | 18.5–24.9 | Not specified | Not specified | Not specified | Inclusion: Age 18–42 years, First FET, ICSI cycles Exclusion: Not specified, only single blastocyst transfers were analyzed in live birth rate | Blastocyst | Autologous | Not specified | First | HRT after pituitary suppression |
Prost et al. [27] | France | 2020 | 18.5–24.9 | NA | 21.5 ± 1.8 | 34 ± 3.1 | Inclusion: All consecutive autologous FBT cycles Exclusion: Oocyte donation, natural or stimulated, PGT cycles; risk factors for recurrent pregnancy loss | Blastocyst | Autologous | Both | All | HRT |
Qiu et al. [28] | China | 2019 | 18.5–24.9 | 17.62 ± 0.8 | 21.86 ± 1.8 | 28.1 ± 1.6 | Inclusion: PCOS Exclusion: Serious and unstable disease; gynecological borderline and malignant tumors; other metabolic disorders; chromosomal abnormalities; congenital uterine malformations | Both | Autologous | Only PCOS | First | HRT or mild stimulation |
Tang et al. [29] | China | 2021 | 18.5–24.9 | 17.53 ± 3.1 | 21.61 ± 1.7 | 26.37 ± 1.9 | Inclusion: Age 20–40 years, FSH < 10 IU/L Exclusion: Lack of antral follicles or FSH > 10 IU/L; diabetes or hypertension; recurrent pregnancy loss; endocrine abnormalities; drugs or diseases that can cause underweight | Both | Autologous | Not PCOS | First | depends on patients |
Rittenberg et al. [30] | UK | 2011 | 18.5–24.9 | NA | 21.6 ± 1.9 | 27.8 ± 2.2 | Inclusion: Single blastocyst transfer Exclusion: Age > 40 years, BMI < 18.5 kg/m2; PGD, donated oocytes; embryos frozen for fertility preservation; monozygotic twin gestation | Blastocyst | Autologous | Both | Not specified | HRT after pituitary suppression |
Wang et al. [31] | China | 2017 | 18.5–24.9 | NA | 21.28 ± 0.0 | 27.13 ± 0.1 | Inclusion: Age < 40 years; FSH < 10 IU/L; AFC of more than 3; regular menstrual cycles; male, unexplained, or tubal factors infertility Exclusion: Accept HRT treatments in previous 3 month; PCOS; functional ovarian cyst with E2 > 100 pg/mL; PGD, IVM, donor cycles; any contraindications to ovarian stimulation treatment; presence of fresh embryo transplantation | Both | Autologous | Not PCOS | Not specified | depends on patients' condition |
Zhang et al. [32] | China | 2019 | 18.5–22.9 | 17.66 ± 0.7 | 20.67 ± 1.2 | 25.68 ± 1.5 | Inclusion: First FET cycles, high quality embryo Exclusion: Age > 40 years; recurrent pregnancy loss; previous IVF attempts; submucosal fibroids or polyps, intramural fibroids > 4 cm, hydrosalpinx, and congenital uterine malformation; hypertension; diabetes; thyroid dysfunction | Both | Autologous | Both | First | depends on patients' condition |