A woman lacking vital nutrients before and during pregnancy or using tobacco and alcohol during pregnancy faces a higher risk of pregnancy complications. Surprisingly, these same prenatal factors also increase her child’s risk of behavioral and learning disabilities and lifelong risk of future disease.
Prevention begins with education. Long before young people may become involved in pregnancy-related issues, it is vital that they appreciate how a woman's health and lifestyle choices shape the lifelong health of her baby.
"The Biggest Story in Human Health"
A steady stream of new research reveals that during pregnancy—and sometimes long before pregnancy—a woman's health, nutrition, and lifestyle choices significantly influence the health and growth of her baby before birth, her baby's birth weight and size, and whether her baby is born premature or full-term.
Even more surprising is that these same prenatal factors also help shape her child's lifelong health and cognitive ability. They also help determine her child's risk of developing diseases such as heart disease, obesity, and diabetes, and learning and behavioral disorders such as Attention Deficit Hyperactivity Disorder (ADHD) and conduct disorder.
This research, twenty plus years in the making, is helping to define how a woman's health before and during pregnancy may impact her child's entire life. It is also revealing how eating properly and avoiding harmful substances may sharply reduce the risk of certain diseases and disabilities, enhance human health and achievement, and save lives.
To briefly cite a specific example, researchers recently reported that women receiving folic acid supplements for at least one year before conception enjoyed a 70% reduction in severe prematurity and a 50% reduction in moderately severe prematurity. The complications that accompany premature birth can be significant. In fact, the societal cost to treat prematurity in the United States is estimated at $26.2 billion per year. The possibility of sharply reducing the incidence of a major medical complication like premature birth with an inexpensive daily supplement highlights the power of prevention.
Dr. Peter Nathanielsz, a prominent researcher in this area, calls the amazing link between prenatal health and lifelong health "the biggest story in human health" and, in no uncertain terms states, "we need to wake up."
The Theory of Fetal Programming
During critical development periods, an embryo or fetus lacking essential nutrients or oxygen or exposed to harmful substances such as tobacco or alcohol may be forced to alter its normal development process in order to survive. These adaptations may result in permanently altering the structure and function of some fetal organs, which may increase the risk of certain diseases later in life. "Fetal programming" is the phrase often used to describe permanent changes resulting from the prenatal environment.
For example, when a fetus is lacking oxygen, the brain and heart receive oxygen at the expense of other organs such as the liver, pancreas, and kidneys. As a result, these organs may not grow to normal size or achieve normal function.
The link between prenatal health and lifelong health can be more easily understood by considering that most cell generations appear before birth while most cells appear after birth. The graph below shows the relationship between the number of cells in the human body, and the number of cell generations at several milestones in the human life cycle. The term "cell generations" refers to the process where one cell divides into two, two into four, and so on. Each division represents one cell generation. The number of cell generations is shown along the horizontal axis while the number of cells is shown along the vertical axis.
We know that fertilization produces a single-cell embryo prior to the onset of cell division. This explains the first point on the graph (one cell, zero divisions). The number of cells in an adult is estimated to be between 30 trillion and 100 trillion. To reach these large numbers from a single cell, 46 to 47 generations of cells, to a first approximation, are required. This explains the last milestone on the graph.
The second milestone in the human life cycle shown on the graph occurs after thirty generations of cell divisions when approximately one billion cells are present. You may be surprised to learn that this occurs at the end of the embryonic period, just 8 weeks after fertilization.
The third milestone on the graph is shown following 41 generations, which coincides approximately with birth when an estimated two trillion cells are present.
This graph illustrates that most cell generations appear before birth while most cells appear after birth. Therefore, it is perfectly reasonable to think that the quality of the prenatal environment in which the first 41 generations of cells develop before birth will influence the health of all the cells that develop after birth.
Prenatal Factors and Lifelong Health
Here are some examples describing the long-term consequences of prenatal events. There is no substitute at any age for a well balanced diet and avoiding exposure to harmful substances.
Supplementation with folic acid before and during early pregnancy decreases the risk of neural tube defects —the most common of which is spina bifida. Neural tube defects occur within four weeks after fertilization —before most women even know they are pregnant. The Centers for Disease Control and many other organizations have long recommended daily folic acid supplements in women of childbearing age.
Folic acid deficiency before and during pregnancy has additional consequences beyond the risk of neural tube defects. It is also associated with an increased risk of low birth weight and premature birth. In fact, a recent study found that pregnant women who take folic acid supplements beginning one year prior to conception experienced a 70% reduction in the incidence of severe prematurity (prior to 26 weeks post-conception) and a 50% reduction in moderately severe prematurity.
It is well established that iodine deficiency during pregnancy and early childhood causes brain damage and is the leading cause of preventable mental retardation around the globe. For this reason, table salt is supplemented with iodine in many parts of the world in an effort to address widespread iodine deficiency.
Vitamin D deficiency during pregnancy results in lower bone mass at birth and lower bone mass by ages 8 or 9 years old, which raises the risk later in life of osteoporosis, a condition particularly common in women.
Asthma, the leading cause of school absenteeism among chronic illnesses, has recently been linked to low vitamin E intake during pregnancy. A 2005 study reported a five-fold increase in the risk of asthma or asthma-like symptoms among five-year-old children whose mothers reported low Vitamin E intake as compared to children of mothers with high Vitamin E intake. Giving vitamin E to these children did not improve their asthma.
The same study also reported a nearly two-fold increased risk of asthma in five-year-olds whose mothers had the lowest zinc intake during pregnancy.
Low vitamin D intake during pregnancy is associated with increased wheezing symptoms in five-year-old children (but not asthma), independent of their vitamin D intake after birth.
An increased risk of ADHD and anxiety was reported among 8- and 9-year-olds whose mothers experienced high stress between 12 and 22 weeks of postmenstrual age (or between 10 and 20 weeks post fertilization).
High levels of stress later in pregnancy did not translate into increased risks in the children under study.
It is well known that smoking during pregnancy impairs fetal growth, and is associated with a higher risk of miscarriage and premature birth. It also slightly increases the risk of certain brain cancers in young children.
Prenatal tobacco exposure is also linked to a higher risk of obesity at ages 3, 4˝, 5 to 7, and 33. This effect appears to be dose related—the more a pregnant woman smokes, the higher the risk of obesity in her children.
Other reported complications include: a two- to six-fold greater risk of Sudden Infant Death Syndrome (SIDS), and an increased risk of Attention Deficit Hyperactivity Disorder (ADHD), noninsulin-dependent diabetes, and tobacco experimentation during childhood. The risk of nicotine dependence in adults is also elevated.
Additionally, prenatal tobacco exposure is linked with an increased risk of conduct disorder, a collection of emotional and behavioral disabilities.
Prenatal alcohol exposure is widely known as the sole cause of Fetal Alcohol Syndrome, which is the most common preventable cause of mental retardation in the United States and other developed countries. It is also associated with lower IQ and a higher rate of fetal mortality.
Less well known is the increased risk of ADHD, conduct disorder, and intrauterine growth retardation. Prenatal alcohol exposure is also associated with an increased risk of alcohol use during adolescence and dependence in early adulthood, and lower academic performance.
Inadequate nutrition during pregnancy is a major cause of intrauterine growth retardation (IUGR) and low birth weight, which are associated with decreased adult height and cognitive ability, and an increased risk of obesity, hypertension or high blood pressure, stroke, non-insulin dependent diabetes, and coronary artery disease leading to heart attack.
It is important to remember that many of the links between prenatal and lifelong health require additional research to confirm research findings and to further delineate the risks involved.
Proving cause and effect relationships in medicine is always difficult. For example, despite overwhelming evidence that tobacco causes human disease, there are still those who dispute this evidence. In the case of fetal programming, it is virtually impossible to prove definitive causal relationships when discussing events during pregnancy that may affect health 20 or 30 or 50 years later.
But while current research does not prove causality and despite some disagreement among experts about the nuances of fetal programming theory, the vast majority of studies provide clear and convincing evidence that preconception health and prenatal health play a vitally important role in every child’s development.
Hope for the Future
It is important to keep in mind that, although these prenatal factors increase the risk of certain complications, they in no way guarantee that any complication will occur. Anyone who has experienced a less-than-ideal pregnancy should not panic or lose hope. Even if a problem develops, most are treatable and many have other risk factors that can be modified to minimize risk. The good news is, new ways to prevent long-term consequences have already been discovered.
Nevertheless, given the many associations between prenatal events and lifelong health that have been reported worldwide, it is imperative to do all we can to improve women’s health before pregnancy and insure the best possible prenatal care for everyone.