Dear Editor-in-Chief
Infertility rates were reported different in developed regions in comparison with non-developed ones. The prevalence rate of infertility has been reported to elevate from 3.5% to 16.7% in more developed nations and from 6.9% to 9.3% in less-developed ones (1). In the various continents, there is no single epidemic of infertility rates (2). Therefore, it is necessary to investigate every continent separately and determine clusters of countries with similar trends.
Data for prevalence rates of infertility during 1990–2015 (in 5-year intervals; data for next 5 years is not yet available) in 198 country and regions were derived from Global Burden of Diseases (GBD) study (5). The trend of infertility rate was estimated, separately for males and females in six regions and also among developing and developed countries. Then all countries were classified into subgroups with similar trends over the years.
Table 1 shows the mean ± SD of infertility rate as well as Latent Growth model (LGM) results. The intercepts represent the estimated overall mean of initial infertility rate. A positive and negative slope reveal that the rate had an incremental and decremental trend over the period, respectively. For interpretation of results, the estimates for Asian male (intercept=684, slope=22.25) reveals that the initial rate of infertility in this region has been 684 per 100000 in 1990 and it has an incremental trend with a slope of 22.25 until 2015. The highest and the lowest increase in the male infertility has been estimated in Asia (rate of 22.5) and Australia & Oceania (rate of 5.56). Moreover, female infertility in Asia and North American has the highest and the lowest increase rate of 10.18 vs 5.89, respectively. However, female in developed countries had a decremental trend of −2, the others in developing and developed countries showed an incremental trend.
Table 1:
Infertility rates (per 100,000) as mean ± SD and estimates from the LGM by the regions for analysis of trends
| Region | Gender | Years | LGM estimates | ||||||
|---|---|---|---|---|---|---|---|---|---|
|
| |||||||||
| 1990 | 1995 | 2000 | 2005 | 2010 | 2015 | Intercept | Slope | ||
| Asia | Male | 684±251 | 710.3±273.1 | 721.5±281 | 751.9±307.7 | 804.2±356.8 | 780.1±309.8 | 684 | 22.25 |
| Female | 530.3±328.2 | 514.7±338.4 | 499.2±319.9 | 497.5±302.1 | 550.1±351.9 | 587.2±379.2 | 509.07 | 10.18 | |
| Africa | Male | 941.1±476.5 | 933±458.7 | 933.4±489.2 | 954±510 | 970.1±502.5 | 1005.8±497 | 922.10 | 12.56 |
| Female | 315.2±305.1 | 277.5±299.9 | 262.9±325.9 | 281.4±352.3 | 310.7±382.1 | 318.2±363.4 | 283.49 | 6.05 | |
| Europe | Male | 626.8±246.8 | 630.9±243.3 | 654.2±276.9 | 670.1±285.6 | 670.6±292.1 | 613±287.45 | 628.77 | 10.41 |
| Female | 556.1±418.1 | 535±426.8 | 568.5±480.4 | 571.4±462.4 | 549.5±437.4 | 567.4±433.8 | 553.07 | −2.075 | |
| North America | Male | 733.5±295.8 | 767±327.5 | 786.8±343.8 | 805.5±357.1 | 814.3±341.4 | 778.7±298 | 750.88 | 16.33 |
| Female | 1506.3±735.7 | 1573.7±801.5 | 1580.5±815 | 1582±817.7 | 1572.8±769.9 | 1627.8±758.4 | 1563.25 | 5.89 | |
| South America | Male | 493.8±316.4 | 486.1±328.1 | 517.7±352.9 | 526.2±290.1 | 533.4±265.8 | 533.6±275 | 482.67 | 14.04 |
| Female | 876.8±954.4 | 817.8±956.2 | 888±1030.2 | 859.9±818.2 | 854.4±742 | 907±776.4 | 835.9 | 6.35 | |
| Australia& Oceania | Male | 867.2±332.1 | 884.6±324.8 | 893.8±318.4 | 906.1±319.7 | 909.6±319.6 | 907.2±327.2 | 872.94 | 5.56 |
| Female | 917.9±391.4 | 928±397.3 | 941.7±361.3 | 934.3±409.7 | 952.7±424.7 | 876±392.4 | 921.21 | 6.27 | |
| Developing Countries | Male | 769±231.4 | 772.2±367.8 | 784.1±390.1 | 807.4±399.5 | 831.2±394.7 | 843.1±393.8 | 757.1 | 17.5 |
| Female | 589±578.3 | 569.5±604 | 569.7±636.2 | 577.5±611.9 | 610.5±611.2 | 631±614.9 | 565 | 11.4 | |
| Developed Countries | Male | 698±329.3 | 724.7±347 | 741±350 | 755.5±369.7 | 764.9±401.6 | 696.9±364.8 | 708.3 | 15 |
| Female | 807.3±617.9 | 810.9±659.2 | 829.8±654.6 | 819.6±649.5 | 797.6±621.9 | 817.1±633 | 817.4 | −1.8 | |
The results of fitting the Growth mixture models (GMM) showed that most countries were classified into classes with the incremental trends, the infertility rates decreased in some clusters, including Cameroon, Niger (male) and Barbados, Guyana, Mozambique, Pakistan and Virgin Islands (female). The maps in Fig. 1 reveals the clusters of countries with estimated similar trend of infertility rates from 1990 up to 2015.
Fig. 1:
World’s cluster map based on female (up) and male (down) infertility outbreak trends within past decades
Footnotes
Conflict of interest
The authors declare that there is no conflict of interests.
References
- 1.Mascarenhas MN, Flaxman SR, Boerma T, et al. (2012). National, regional, and global trends in infertility prevalence since 1990: a systematic analysis of 277 health surveys. PLoS Med, 9(12):e1001356. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.ESHRE Capri Workshop Group (2010). Europe the continent with the lowest fertility. Hum Reprod Update, 16(6):590–602. [DOI] [PubMed] [Google Scholar]
- 3.Global Burden of Disease Collaborative Network. Seattle, United States: Institute for Health Metrics and Evaluation (IHME), 2018. ©University of Washington. http://ghdx.healthdata.org/gbd-results-tool [Google Scholar]