Biological Determinants of Low Fertility Rate: Reproductive Ageing a Crucial Factor
In rapidly ageing societies like Singapore, the persistent decline in global fertility rates represents a major public health and socioeconomic challenge. While policy discussions often focus on sociocultural and economic influences, biological determinants, especially reproductive ageing — remain comparatively under-recognized. I would like to highlight that reproductive ageing is a critical driver of reduced fertility potential as couples decide to delay childbearing until later in life.
Reproductive ageing in women involves a progressive decline in both the quantity and quality of oocytes, driven by mechanisms such as mitochondrial dysfunction, cumulative DNA damage, and changes in the ovarian microenvironment. Importantly, these processes begin well before menopause, with measurable reductions in fecundity occurring from the early thirties. As childbearing is increasingly delayed, the biological limits imposed by ovarian ageing are becoming more pronounced, contributing significantly to lower fertility rates.
There also exists a substantial inter-individual variability in reproductive ageing trajectories, shaped by genetic, environmental, and metabolic factors. However, current clinical tools for assessing ovarian reserve and predicting reproductive lifespan remain imprecise, limiting the ability to provide individualized reproductive counselling and early intervention.
Addressing declining fertility rates therefore requires a paradigm shift from reactive fertility treatment to proactive strategies that prioritize ovarian health across the life course. This includes investment in research to identify early biomarkers of ovarian decline and senescence, better understand underlying molecular pathways, and develop interventions that can preserve or extend reproductive function. Although this work emphasizes on reproductive ageing in women, the impact of reproductive senescence on male fertility cannot be undermined as it can significantly impact on reproductive outcomes.
Reproductive ageing represents a fundamental biological constraint on fertility with significant demographic implications. Increased funding and interdisciplinary research efforts are urgently needed to close existing knowledge gaps, inform policy decision-making, and support individuals in achieving their reproductive goals.
