Seasonality in human reproduction: an update

Area of Science:

• Reproductive Biology
• Human Reproduction
• Chronobiology

Background:

• Epidemiological studies consistently show seasonal variations in human conception and birth rates globally.
• While seasonal effects on mammalian reproduction are well-studied, mechanisms influencing human and primate reproduction remain less understood.
• Existing research suggests potential links between seasonal changes, sperm quality, and conception rates.

Purpose of the Study:

• To critically review the influence of seasonal variations on human and primate fertility.
• To explore the potential mechanisms mediating these seasonal reproductive effects.
• To discuss the implications of seasonal variations for assisted reproductive technologies and infertility.

Main Methods:

• Literature review of epidemiological studies on seasonal reproductive patterns.
• Analysis of research on seasonal influences on sperm quality, ovulation, and endometrial receptivity.
• Synthesis of evidence regarding seasonal effects on human and primate reproduction.

Main Results:

• Seasonal conception rates differ geographically: lower in summer in sub-equatorial regions, higher in summer in northern latitudes.
• Potential mechanisms include seasonal changes in sperm quality, anterior pituitary-ovarian axis activity, ovulation rates, ovum quality, and endometrial receptivity.
• Observed birth rate peaks in spring in northern countries correlate with summer conception peaks.

Conclusions:

• Seasonal variations significantly impact human and primate fertility.
• Understanding these seasonal effects is crucial for managing infertility and optimizing assisted reproductive technologies.
• Further research is needed to elucidate the precise mechanisms and mediators of seasonal reproductive influences.