Table II.
Number of studies and range of 12-month period and lifetime infertility prevalence estimates by study descriptors.
| Study characteristics | Number of studies1 |
Number and range of 12-month total infertility prevalence estimates (%)2 |
|||
|---|---|---|---|---|---|
| All studies (studies with 12-month estimates) | Number of period estimates3 | Period prevalence | Number of lifetime estimates3 | Lifetime prevalence | |
| Total | 133 (84) | 69 | 1.6–34.0 | 65 | 3.3–39.7 |
| Methodological approaches | |||||
| Prospective TTP design | 3 (3) | 3 | 13.6–28.0 | – | – |
| Retrospective TTP design | 34 (24) | 25 | 5.0–32.0 | 15 | 3.3–35.3 |
| Current duration design | 6 (5) | 10 | 9.4–34.0 | – | – |
| Self-reported infertility measure | 61 (39) | 16 | 4.0–18.0 | 45 | 4.2–39.7 |
| Constructed infertility measure | 23 (8) | 12 | 6.0–17.0 | – | – |
| Undetermined | 13 (6) | 3 | 1.6–13.3 | 5 | 10.1–20.9 |
| Definitional characteristics | |||||
| Numerator (duration only) | |||||
| Intentions included4 | 65 (46) | 22 | 7.0–32.0 | 42 | 4.2–39.7 |
| Intentions not considered | 61 (37) | 44 | 1.6–34.0 | 14 | 3.3–35.3 |
| Numerator (duration and/or receipt of care included) | |||||
| Intentions included4 | 8 (7) | 2 | 12.0–12.3 | 8 | 11.0–26.0 |
| Intentions not considered | 2 (2) | 1 | 18.0 | 1 | 35.0 |
| Numerator (subjective evaluation with or without duration) | |||||
| Intentions included4 | 10 (1) | – | – | 3 | 11.4–16.4 |
| Intentions not considered or unknown | 10 (1) | 1 | 7.74 | – | – |
| Denominator | |||||
| All regardless of risk of pregnancy | 74 (41) | 19 | 1.6–17.0 | 35 | 3.3–35.0 |
| Ever at risk of pregnancy5 | 37 (26) | 30 | 4.2–34.0 | 13 | 8.2–35.3 |
| Attempting to conceive4 | 40 (30) | 20 | 9.4–32.0 | 17 | 5.8–39.7 |
| Study population characteristics | |||||
| Sample type | |||||
| General population-based | 118 (71) | 47 | 1.6–34.0 | 65 | 3.3–39.7 |
| Clinic-based | 15 (13) | 22 | 5.0–28.0 | – | – |
| Sex of respondent | |||||
| Female | 109 (72) | 54 | 1.6–34.0 | 56 | 3.3–39.7 |
| Male | 10 (10) | 5 | 7.0–15.3 | 9 | 8.2–21.8 |
| Combined6 | 18 (9) | 10 | 4.2–28.0 | – | – |
| Not reported | 1 (–) | – | – | – | – |
| Income Level 7 | |||||
| High-income countries | 70 (55) | 43 | 5.0–34.0 | 52 | 4.2–35.3 |
| Low- and middle-income countries | 65 (29) | 26 | 1.6–32.0 | 13 | 3.3–39.7 |
| Region 8 | |||||
| Africa Region | 24 (8) | 6 | 9.5–32.0 | 4 | 9.3–15.8 |
| Eastern Mediterranean Region | 15 (6) | 3 | 5.2–15.2 | 4 | 3.3–21.2 |
| European Region | 47 (37) | 32 | 5.0–34.0 | 25 | 9.0–31.8 |
| South-East Asia Region | 12 (–) | – | – | – | – |
| Region of the Americas | 24 (15) | 16 | 4.0–15.7 | 15 | 4.2–35.3 |
| Western Pacific Region | 29 (19) | 12 | 1.6–28.0 | 17 | 8.2–39.7 |
Some studies reported multiple prevalence estimates by applying different definitional or study population characteristics. In these instances, studies were included in more than one tally.
12-month estimates of resolved and unresolved infertility. Outlier 12-month infertility estimate is not reported in Table II. Outliers were determined based on their magnitude and justification in the respective studies regarding their ability to capture infertility. Outlier infertility estimates are documented in Supplementary Data S10.
Some studies reported multiple prevalence estimates by applying different definitional or study population characteristics. In these instances, multiple estimates from a single study may be included in the same tally.
Includes individuals wanting a child and/or trying to conceive.
Includes any individual ever at risk of a pregnancy. May include studies that used marital status as a proxy for being at risk of pregnancy.
Includes studies that reported estimates for male and female respondents or couple respondents.
Defined based on World Bank classifications at the time of the systematic review (The World Bank. Countries and economies. 2021; Available from: https://data.worldbank.org/country).
Defined based on World Health Organization regional groupings (World Health Organization. 2022; Available from: https://www.who.int/about/who-we-are/regional-offices).
TTP, time to pregnancy.