Table 1.
General Characteristics of the included studies
| References | Country | Population | Study design | sex | Sample size | Duration of follow up (Year) | Exposure variable Definition of Obesity |
Outcome investigated | Quality of the studies |
|---|---|---|---|---|---|---|---|---|---|
| Barclay 2020 | Sweden | 17–20 years old Men born in Sweden between 1965–1972 | Retrospective Cohort | Male | 405,427 | 44 |
Overweight BMI : (25-29.99) Obese BMI ≥ 30 |
Fertility up to age 40 or older | Good |
| Frisco 2012 | United States | 21–23 Years old females | Retrospective cohort | Female | 3,977 | 20 |
Overweight BMI : (25-29.99) Obese BMI ≥ 30 |
Number of children: No children : 0 1 or more live birth: 1 |
Good |
| He 2018 | Australia | Australian school children aged 7–15 years | Prospective cohort | Male and Female |
8,498 4,191 Girls 4307 Boys |
22.6 |
Overweight BMI : (25-29.99) Obese BMI ≥ 30, Abdominal obesity was defined as WHtR R0.5 |
Infertility (was defined as having difficulty conceiving (had tried for ≥ 12 months to become pregnant without succeeding) or having seen a doctor because of trouble becoming pregnant) | Good |
| Jacobs 2016 | United States | Children aged 5 to 14 years old | Prospective cohort | Female | 5,824 | 33 |
85 ≤ BMI percentile ≤ 94 : Overweight BMI Percentile ≥ 95 : Obese Subscapular and triceps skinfold thicknesses percentile: High : 85 ≤ Percentile ≤ 94 Very high: 95 ≥ Percentile |
Fertility difficulties: The women who answered Yes two any of the 3 question below were considered infertility difficulty group: 1.Taking any fertility drugs 2.Trying to become pregnant and were unable to 3.visiting doctor for becoming pregnant |
Good |
| Jokela 2008 | United States | 17–24 years old young adults | Prospective cohort | Male and Female |
12,073 5982 women 6091 men |
23 |
Overweight BMI : (25-29.99) Obese BMI ≥ 30 |
Number of children desired | Good |
| Kahn 2019 | United States | Children from health and development cohort until 44 Years of old | Prospective cohort | Male | 193 | 44 |
Overweight BMI : (25-29.99) Obese BMI ≥ 30 |
Sperm concentration, motility, and morphology | Good |
| Lake 1997 | United Kingdom | Children born on 3rd to 9th of March 1958 | Prospective cohort | Female | 5,799 | 26 | Age specific BMI cut-off |
Menstural problems, Subfertility, HTN Subfertility defined as time taken to conceive from cessation of contraception |
Good |
| Laru 2021 | Finland | Women born in 1966 | Prospective cohort | Female | 4,382 | 50 |
85 ≤ BMI percentile ≤ 94 : Overweight BMI Percentile ≥ 95 : Obese |
Impaired reproductive function defined as decreased fecundability, need for infertility assessment and treatment by 46 years of age. Childlessness and number of children also extracted. |
Good |
| Polotsky 2010 | United States | Women aged between 42–52 | Retrospective cohort | Female | 3,302 | NR |
Overweight BMI : (25-29.99) Obese BMI ≥ 30 |
Nulliparity and nulligravidity | Good |
| Ramlau-Hansen 2010 | Denmark | 5–8 Years | Retrospective Cohort | Males | 260 | 22 | High prepubertal BMI (16.21–22.58 kg/m2) | Sperm Concentration, Sperm volume, Sperm total count, percent normal morphology sperm, percent motile sperm, Testosterone, Estradio, FSH, LH, SHBG, Inhibin B. | Good |
| Rich-Edwards 1994 | United States | Females registered nurses 25 to 42 years old | Nested case-control study | Female |
2,527 Case 46,718 Control |
NR | BMI categories | Infertility due to ovulatory disorder | Good |
BMI: Body Mass Index, FSH: Follicle Stimulating Hormone, LH: Luteinizing Hormone, SHBG: Sex-Hormone Binding Globulin