Is human fecundity declining in Western countries?

Area of Science:

• Reproductive Health
• Environmental Medicine
• Epidemiology

Background:

• Widespread concern exists regarding declining sperm counts and potential environmental pollutant impacts on human fecundity since the 1992 Carlsen report.
• Subsequent studies on sperm quality and fecundity trends have yielded diverse and complex results, making definitive conclusions challenging.
• Current data is insufficient to confirm or reject claims of declining population fecundity or the role of environmental pollutants.

Purpose of the Study:

• To address the uncertainty surrounding population fecundity trends and the influence of environmental factors on human reproduction.
• To highlight the critical need for a robust surveillance system to monitor male reproductive health and couple fecundity.
• To propose a feasible monitoring system for future reproductive health assessments.

Main Methods:

• The study critically evaluates existing research on secular trends in sperm quality and fecundity.
• It identifies the lack of a systematic surveillance system as the primary obstacle to understanding population fecundity.
• The authors propose a monitoring system combining total sperm counts and time to pregnancy data.

Main Results:

• Existing studies on sperm counts and fecundity trends are inconclusive and difficult to interpret.
• There is a significant lack of an appropriate surveillance system to track male reproductive health and couple fecundity.
• A proposed monitoring system combining sperm counts and time to pregnancy is deemed feasible.

Conclusions:

• The current evidence is insufficient to confirm or reject a decline in population fecundity or the involvement of environmental pollutants.
• Establishing a dedicated surveillance system is essential for accurately assessing reproductive health trends.
• Implementing a monitoring system using sperm counts and time to pregnancy is proposed as a vital step for future public health concern.