PLANETARY HEALTH WEEKLY

September 15, 2022

By Stephen Bezruchka

Last month we closed the coffin lid on economic inequality.  It is not good for our health, nor for the environment.  What should we do with the proceeds that will come from reigning in inequality?  Spend it on early life.  

As we go from the erection to the resurrection how we are ushered into life determines how we leave it.  To understand how the health of populations is produced requires recognizing the importance of early life along with that of economic inequality as the two foundational pillars. But as we have seen with Japan and Finland in a previous blog, that doesn’t explain enough of why people don’t live so long in the United States.  Understanding health at the population level is not a way of thinking we are exposed to.  Yet that is the critical perspective we must take.

Early Life Lasts a Lifetime

So how to understand early life?  It all started when your father’s sperm fertilized your mother’s ovum to produce a zygote.  Actually, your mother made the ovum that begat you when she was inside your maternal grandmother’s womb. Women are born with all the ova they will ever have.  So your grandmother’s circumstances, conceptually at least, can affect you.  That zygote divides about 42 times to produce a newborn.  There are only about five further cycles of cell division to produce you the adult.  We are talking about exponential growth here which hopefully you studied in high school (2, 4, 8, 16, 32, 64, etc.). 

Cell division is a sensitive period that can be affected by many circumstances.  Various plant and animal experiments demonstrate that radiation, various chemicals, hormones and even stress can affect the process.  Influencing the huge number of cell divisions that happen in the 9 months of pregnancy would be far more efficient than working on the next five cycles to adulthood.  The fetus is very sensitive to what is going on around her or him. Dr. David Barker, a doctor epidemiologist, tracked high infant mortality rates in parts of England and Wales to heart disease mortality there 45 years later.  Barker found birth records of men born between 1911 and 1930 in Hertfordshire, England with birthweight and weight at one year.  He tracked these individuals and found those with the lowest birthweight at one year had the highest rates of death from heart disease.  He hypothesized that poor nutrition during pregnancy led to low birthweight and consequent heart disease.  These findings were reported in 1989.  Further research demonstrated that low birthweight was related to many diseases in adulthood, including lung and kidney disease, diabetes, high blood pressure, obesity, depression among others.  See this video about his work at: https://drive.google.com/file/d/0B4DCgIbsWBF3QTdBV0s2Vk42c2M/view?resourcekey=0-ehL-548mbK0Llxld_9QFsw    

Cohort studies look at a group of people that are followed to see what happens to their health.  A natural experiment occurred during World War II, the Dutch Hunger Winter, when nutritional stress was imposed on the Dutch from November 1944 to April 1945.  Those pregnant during that time were followed to see what the outcomes were for their babies when they became adults.  Fetuses who were exposed to the famine during the early months of their gestation, in contrast to those born before the famine, were more likely to have diabetes, mental disorders, and a lipid blood profile (high cholesterol and tri-glycerides) subjecting them to high risk of coronary artery disease, as well as increased stress sensitivity, female obesity, and many other chronic diseases in adulthood. Those exposed in mid-gestation were prone to lung and kidney disease and diabetes. Those exposed in late gestation had higher rates of diabetes. These findings correspond to periods in the uterus when various organs are being formed. What’s more, the damage isn’t restricted to a single generation—it was also found to perpetuate into successive generations.

When those Dutch famine-affected infants became adults and had children of their own, that second generation tended to have health problems in later life, including diabetes and obesity. This demonstrates the intergenerational transmission of health from those affected by the famine in utero to their own children. Recall how you began your existence in your maternal grandmother’s womb since the ovum that begat you was produced there.  When we explore more biology in a later blog we will find epigenetic explanations (i.e., those that relate to induced DNA changes) for how this happens. 

In 1947 a series of cohort studies began in England that enrolled all those born in the first week of March and continued following them at regular intervals to gauge their health outcomes.  Studies of the 1958 birth cohort, most of whom have not yet died, reveal that using self-assessed health as a proxy measure for mortality, what happened between birth and age seven influenced their health as much as everything afterwards.  Study details and much more are at http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.publhealth.012809.103538   This study led to the summary concept that roughly half of one’s health ((consider odds ratios in Figure 1 above being similar) has been programmed before entering school. 

British birth cohort studies continue.  They have some limitations including people drop out and can’t be followed up, the characteristics of those giving birth today in Britain are quite different from those in 1958, and studies are limited to what was collected in the early period.   

Life course epidemiology considers this mode of research.  Being of low birthweight and being born prematurely compromises adult health.  David Barker studied the Helsinki birth cohort, namely those born in the capital of Finland between 1934 and 1944 to demonstrate early life associations with adult health.  Developmental origins of health and disease (DOHaD) is the cover term for this field of study. 

Being born of low birthweight is the marker that tends to lead to worse health in adulthood.  While your birthweight may have been low, it doesn’t mean that your health is compromised as the effect is seen in populations.  Populations in poverty and subjected to racism show health effects of low birthweight.  This point needs to be stressed, namely we are speaking of findings affecting populations such that there are individuals born with low birthweight who don’t have adult health compromises.  

The first thousand days after conception, that is around the time you are blowing out two candles on your second birthday cake, is now considered the critical period when a large fraction of adult health is programmed. 

What is important in the first year or two after birth?  John Bowlby, a British psychiatrist, studied British orphans after World War II.  He developed the concept of attachment, relating to caregivers in the first few years.  Secure attachment was more likely when there was a single caregiver present in the first year.  Newborn babies don’t have good vision but can see marked contrast.  A single caregiver’s eyes becomes a source of comfort.  Readers can likely easily recall their mother or early caregiver’s eyes.  As a baby develops and crawls around knowing there is a secure base to return to with reassuring eyes allows exploration of surroundings.  Secure attachment beginning in early life is now seen to be critical for healthy adulthood.  Bowlby found the presence of a second pair of eyes in the child’s second year good.  Too many eyes or no eyes led to serious developmental troubles later in life.   

There are many different ways children are reared globally.  The African proverb “it takes a village to raise a child” reflects the communal aspect operating there.  Whatever the way children are raised no one will deny the time and resources needed to produce healthy adults.  National policies impact child rearing.  Only two countries do not have a national policy of providing paid maternity leave after a woman delivers a baby.  One is the United States.  The other is Papua New Guinea.  Every other nation provides paid time off after you have a baby.  Many studies attest to the health benefits that accrue.  Another reason, then, for poor U.S. health status, with some 50 nations having lower mortality rates, relates to its lack of national support for early life. 

There are many aspects of early life to explore as we conclude that early life lasts a lifetime.  Summary details at https://journals.uvic.ca/index.php/ijcyfs/article/view/13499/  Future blogs will explore adverse childhood experiences (ACEs) and parenting. 

First we need to consider how a country that has a great deal of poverty affects everyone’s health in that country.  The next blog will explore that concept as well as presenting the 2021 Health Olympics tally from the 2022 United Nations Human Development Report.  Comparing the ranking from the February 2022 blog, we find Canada is holding its own but the United States is in a free-fall.