Animals That Can Abort Pregnancy

Summary: Abortion is a mechanism utilized by several female animals, including humans, to terminate an unwanted or risky pregnancy. Surprisingly, some animals exhibit the capability of inducing abortion naturally under certain circumstances. Some animals can end their pregnancies as a means of reducing sources of stress which can threaten their physical and psychological well-being. In this article, we will explore various factors that compel certain animals to abort their pregnancies.

1. Environmental Factors

Animals perceive environmental changes differently. Physical or biological stressors like global warming, pollution, availability of essential food and nutrition, and seasonal changes can cause imbalances in hormonal levels leading to an automatic or spontaneous abortion in animals. For instance, African elephants avoid migratory calving sites due to droughts, but when there’s a scarcity of food and water for the pregnant elephant, she has no other option than to abort her pregnancy. Similarly, studies have shown that damsels in insects tend to reabsorb their fetuses without mating when exposed to adverse conditions.

In addition, researchers have discovered that some species of bats also undergo spontaneous abortion in response to low temperatures, food scarcity, and extreme climatic conditions. These physiological mechanisms allow animals to avoid pregnancy during unfavorable conditions and conserve energy for other body processes.

Lastly, natural disasters like hurricanes, tsunamis, floods, and volcanic eruptions can disrupt animal habitats, leading to the death of young ones and pregnant females, thus causing abortions.

2. Social Factors

Social factors are also relevant in the selection for gestation in many species of animals. Many social animals establish subordinate social ranks, with fewer breeding opportunities for lower-ranking members.

In cases where dominant females are unable to mate or establish strong bonds with males in the troop, they sometimes terminate their pregnancy to keep their status and remain valuable contributors to the troop. For instance, dominant females in house mice and rats can terminate pregnancies due to social cues or signals from other members of the same species.

Moreover, some animals may terminate pregnancies when there’s an increase in population density or competition for resources, which could decrease the chances of survival for offspring.

3. Predation

Predation is a serious threat to many pregnant animals. To prevent predators from detecting and attacking them, expecting mothers undergo several adaptations, including changes in their physical appearance, camouflage, or enhancing their agility. However, if the predators are undeterred, the mother may induce abortion to preserve her life instead of giving birth under hostile conditions and subjecting the young to death and vulnerability.

Studies have shown that some primates, like spider monkeys, modify their mating behavior to avoid being detected by predators. When mated by multiple males, they can selectively terminate pregnancies from unwanted paternity to reduce the burden of caring for offspring born under unfavorable conditions: Poor habitat, poor climate, or in the presence of predators that would be hostile to the newborn.

In other cases, shepherding birds, like swallows, opt to abandon the breeding sites and re-migrate to new habitats with better protection, favorable climates, and food sources. This strategy reduces the rate of fetal mortalities and increases the chances of successful breeding and reproduction.

4. Health Factors

Aborting pregnancy can also be an adaptive response mechanism to reduce maternal deaths and conserve resources for rebuilding their energy reserves. For example, female gazelles tend to abort pregnancies when diagnosed with diseases or medical complications like malnourishment, starvation, parasitism, and infections like Rift Valley Fever Virus.

In solitary desert rodents, gestation can be energetically expensive, which could result in poor prenatal nutrition. In such cases, a female rodent may self-abort to decrease the nutritional burden.

Moreover, female minks have the ability to reabsorb their fetuses when their supply of food drops or when they are too thin to support the pregnancy.

5. Intra-skeletal Factors

The intra-skeletal factor leading to abortion is fairly rare in animals. However, it can occur in some animals due to complications in fetal development or injuries that threaten the survival of the offspring. For example, when wolves hunt pregnant caribou females, a fetus whose lungs are punctured will die faster than one whose lungs are intact, thereby necessitating spontaneous abortion in caribou.

In other species like mares, complications such as malformed fetuses or dead embryos in the uterus due to infections may require the animal to terminate the pregnancy. This mechanism can prevent further health problems that could affect the animal or reduce its chances of successful breeding.

Lastly, bird embryos possess epigenetic mechanisms that enable them to detect asymmetry in nutrient supply, resulting in culling or intentional termination of the smaller fetus for independent growth by the larger fetus in diverse species of mass-breeding birds.

Conclusion:

Natural abortion has always been an important phenomenon for several species of animals, occurring in situations where a full-term pregnancy would place too much stress on a mother or make the survival of the offspring improbable. These examples highlight the potential value of terminating pregnancies as an adaptive response to environmental change, social scenarios, predation, intra-skeletal factors, and health challenges. However, it is important to note that the reasons behind abortion remain complex and context-dependent, and not all pregnant animals responding to stressors will choose abortion as an option.

Animals that abort pregnancy are a testament to the wonders of nature. Their unique ability to induce spontaneous or automatic abortion based on environmental, social, and physical factors has served as a mechanism to promote the survival of their species. In conclusion, understanding the various factors influencing natural abortion in animals teaches us lessons we can apply in human healthcare with regards to the choice of abortion.

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