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 |