Contraception and Sterilization Linked to Increased Lifespan: Study Reveals Key Reproduction Trade-offs
- Dec 14
- 2 min read
A groundbreaking international study led by the University of Otago – Ōtākou Whakaihu Waka has established a significant link between blocking reproduction and extended life expectancy in both male and female animals across numerous species. Published in the prestigious journal Nature, the research confirms that contraception and surgical sterilization are associated with an increased lifespan in vertebrates, with effects confirmed across laboratory animals, wild populations, and humans through meta-analysis.
Using comprehensive data gathered from mammals housed in zoos and aquariums globally, the researchers found that ongoing hormonal contraception and permanent surgical sterilization resulted in an average life expectancy increase. Depending on the timing of the treatment and the environment the animal was exposed to, life expectancy was found to increase by 10 to 20 per cent. Reports suggest an average 10% lifespan increase due to these reproduction trade-offs. Co-author Fernando Colchero noted that reproduction is inherently costly, and environments—including human settings with healthcare and nutrition—can either exaggerate or soften these costs.
The mechanisms driving this increased survival, however, differ significantly between sexes. In males, the lifespan extension appears to be strongly tied to hormones. The study found that only castration—the removal of sex hormones—extended the lifespan, whereas vasectomy did not. Lead author Associate Professor Mike Garratt suggests that these hormones may interact with pathways regulating the biology of aging, particularly when removed early in life, as early-life castration showed the strongest effects. Furthermore, blocking reproduction meant males were less likely to die from behavioral interactions involving aggression or risk-seeking.
For females, the benefits stem less from a single hormonal mechanism and more from reducing the substantial energetic and physiological costs associated with reproduction. Lifespan increased following several different forms of sterilization, suggesting the benefit arises from avoiding the intense physical burdens of pregnancy, lactation, and caring for offspring. Not reproducing also meant females were less likely to die from infection and infectious diseases, which is thought to be a result of the high energy demands of reproduction compromising the immune system.
The findings also provide support for the evolutionary rationale behind menopause. Unlike males, researchers found that the effect of contraception on female survival was not dependent on the timing of sterilization. This suggests that avoiding reproduction in later adulthood can still offer later-life survival benefits, even after having produced some offspring.
Despite the clear benefits to lifespan, the study introduces a crucial caveat regarding overall health. While a range of sterilization approaches increased lifespan, ovary removal (oophorectomy), which eliminates ovarian hormone production, was found to impair aspects of health in later life. This complex result helps shed light on the health-survival paradox observed in post-menopausal women, who, on average, outlive men but tend to experience increased frailty and poorer overall health during aging.
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Keywords: Contraception and Sterilization Linked to Increased Lifespan
Contraception and Sterilization Linked to Increased Lifespan
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