Latent impact of COVID-19 in pregnancy?

There was a time when the womb was regarded as a pristine environment for a ‘fetonaut’ to travel safely for 9 months until birth, protected by a shield-like placenta. No longer. The effects of smoking, thalidomide and binge drinking show it is all too vulnerable to external threats.

This realization was extended by David Barker, an epidemiologist whom I met but only once at a Swiss symposium on evolution and health. He was head of a research unit at the University of Southampton and then winning over detractors to his belief that prenatal malnutrition has delayed impacts until midlife or even later.

From searching British medical records, he found low birth weight predicted heart disease, stroke and high blood pressure in adult life, some of the most common medical blights. His critics dismissed the connection as mere correlation—not causation— but as years rolled by there was confirmation from other sources and connections with obesity and diabetes type 2.

At first called the Barker hypothesis, it is now known as the fetal origins of adult disease and as spurred research into late effects beyond those he studied.

pregnant woman ClipartAdverse health effects were also found among Dutch people born to mothers subsisting on a forced daily diet of under 1,000 calories in the last year of World War II. More harms were reported in children conceived around the time of the Chernobyl nuclear disaster and a famine during Chairman Mao’s ‘Great Leap Forward’.  They imply that health and vitality are molded by our environment as well as genes at tender stages that go unseen.

A gravid womb is not like an unmanned space capsule controlled from afar and tossed by storms of plasma from the solar corona. Like an astronaut, a fetus can make adjustments to adapt to changing conditions and improve its safety. This so-called developmental plasticity evolved to increase the chances of survival in times of food shortage. Sometimes called a thrifty phenotype, the baby who emerges is adapted to thrive in the meager circumstances he or she is born to. But if a mismatch exists between prenatal poverty and postnatal affluence the resulting catch-up growth, although apparently welcome, may come at a price if adaptations made in the womb are no longer appropriate.

Adaptations to low oxygen and stress hormones can also play a role, either independently or with malnutrition, and the effects on cell biology and physiology are multifarious and complex. The root of the problem is likely epigenetics in which genes are switched on or off in different cells and states but the sequence of letters in the DNA code are unaltered. Rather insidiously, some epigenetic changes can be inherited by the children and even grandchildren of those originally affected.

So, what has that got to do with the COVID-19 pandemic? Major economic interruptions, like the Great Recession from 2007 that lasted a decade, are known to cause persistent mental and physical health problems, especially among racial and ethnic minorities. But what about acute pandemics that last only months?

Douglas Almond, a health economist at Columbia University, studied people conceived in 1918 and 1919. They suffered far more disadvantages in life if conceived during the flu pandemic than a few months earlier or later, even after adjusting for social class, etc. He reported, “(they) attained lower educational achievement, income, and socioeconomic status … 15% less likely to graduate high school, 15% more likely to be poor, and 20% more likely to be disabled as adults.”

There will be a huge sigh of relief, of course, when COVID-19 is conquered by vaccines, but that won’t be the end of the story. There are likely to be long-term negative consequences for the generation of innocents currently in utero.

This shouldn’t unduly alarm women currently pregnant because the projection is demographic, and the great majority of babies will be fine. The cohort conceived in the flu pandemic a century ago produced as many outstanding people as other generations, men and women like Richard Feynman, Katherine Johnson, Nelson Mandela and Edmund Hillary. Some of them were doubtlessly born in acutely affected communities. But the fetal origins hypothesis urges more research on the unborn to mitigate the chronic personal and societal health impacts of infection.

 

A Day in Dharavi

That day slept in deep memory until Dharavi appeared in news reports about the threat of COVID-19. It wasn’t a Westerner’s curiosity about the plight of poor people that brought me in 2003 after an engagement in Mumbai; it was an introduction to a medical practitioner who worked in the slum. She cared for patients of all kinds, but after flooding from the monsoon she was treating dengue virus. I came with questions.

Mumbai, India
Not a million miles from Dharavi

A first visit to India is an overpowering experience. The immense crowds, poverty, religious spirit, stoicism, heat, and intense colors.

Dharavi squats between arteries of the rail network. As a visitor, I felt the alien I was, but the stares I received, mostly from teenagers in t-shirts, were invariably friendly and I never felt as threatened as in some American inner cities. It’s a community of many religions and none, so creed is less likely to explain low crime than the narrow wealth gap compared to our cities. A millionaire in Dharavi would be incongruous.

The biggest slum in Asia with half a million people crammed in a square mile wasn’t on the tourist trail then, although I hear of tours for inquisitive trekkers today, maybe encouraged by Slumdog Millionaire earning Best Picture at the Academy Awards. It would be a naff voyeur who came to photograph poverty, and some tour companies observe a strict ethical code.

Dharavi defies common notions of slum-living. It’s true that people live cheek by jowl in concrete homes under corrugated roofs beside narrow passageways for noisy streams of pedestrians and auto rickshaws. Overhead there is a tangle of power lines that would look alarming to engineers, polluted waterways horrify environmentalists, and piles of trash condemned by public health departments at home. There is an odor in the air, but it’s not fetid. Some children go barefoot, but most residents take pride in personal appearance and sloth is foreign to them. A beehive is an apt metaphor for the industry inside the maze. There are potteries, tanneries, tailors, shoemakers, food stalls, and recycling enterprises. Some lawyers and doctors reside there, including the one I visited. It is a vibrant community.

Above all, the crush of humanity was the most lasting memory. It’s hard to imagine how people can keep a safe social distance to avoid infection with the coronavirus or find access to facilities for frequent washing of hands. The risk of contagion is acute, and a reminder of the thousands who died of plague there in the 1890s. Remember Dharavi and places like it.

 

Pause for Pangolins

There’s no other mammal like them. Pangolin, the spiny anteater. They look like dinosaurs reduced to the size of domestic cats, miniature ankylosaurs with armored plates (scales) made of keratin instead of bone with sharp points. They may soon join the big reptiles in extinction.

Today is declared World Pangolin Day by those who care about their fate. I read about them before doing this tiny bit to promote their cause.

spiny anteater
Pangolin (courtesy of Pixabay)

These shy, nocturnal animals are found across Asia and in Africa. Eight species in all. Insectivores all. They have a long, sticky tongue for licking up their strict diet of ants and termites, and lacking teeth they grind insect cuticles with stones in their stomach. Evidently capable of long lives, they evolved a slow rate of breeding which makes it hard to restore a depleted population.  Captive breeding is not successful.

Besides the threat of habitat loss from forest clearance, they are scooped out of the wild by poachers on both continents, more trafficked than any other wild mammal. In Africa they are bush meat and in Asia an expensive delicacy for the wealthy while the scales are used in traditional Chinese medicine. According to Wildlife Justice, 8 tonnes of pangolin scales from about 14,000 pangolins and worth HK$ 42M on the illegal market were seized in Hong Kong in 2019 alone. An estimated one million animals have been illegally traded in recent years. Unsustainable. The scales that deter natural predators when they roll up in a ball like a hedgehog are no defense against human plunderers.

They are now in the news for another reason. Sold in Chinese markets where wild animals of various species are kept in adjacent cages, a proximity never encountered in nature, they are suspected vectors of the current coronavirus epidemic. If a zoonotic virus jumps species it may mutate in the new host, animal or human, and become more transmissible. Society didn’t learn the lesson of the SARS coronavirus of 2002 when civets in wildlife markets were the probable source of that epidemic.

There is a danger that pangolins will be demonized where human ignorance, profit and cruelty are really to blame. And yet, there are timid hopes that the Chinese authorities in trying to quench this epidemics will close wildlife markets and prosecute pangolin traffickers. Among so many threats and fears in the world, we take comfort in small hopes.

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