Tips on Having a Healthy Pregnancy

Precautions For Pregnancy

by Kylie Ladd

While you were pregnant did you bypass the brie? Shun the sushi or pass up pate? Most of us were made well aware by our doctors, friends or family that certain foods and activities should be avoided at this time so as to minimize risk to the fetus. These include soft cheeses, raw eggs and meat, smoking and even changing the cat litter. While this advice remains important, new research is emerging that suggests that what we do consume, or even the emotions we experience while pregnant, can have just as important an impact on the long-term health of the child being carried.

It has been well documented for a number of years now that babies exposed to certain conditions in the womb (or in-utero) are often born with particular abnormalities or clinical syndromes in. For example, the children of mothers who did not receive enough folic acid while pregnant have an increased risk of neural tube defects such as spina bifida, while babies born to alcoholic mothers often display fetal alcohol syndrome, a condition characterized by mental retardation and abnormal facial features. While such disorders are apparent soon after birth, scientists now believe that many other diseases emerging decades later may also be related to in-utero environment.

This effect was first postulated by a medical scientist working in the UK named David Barker. Barker found that babies born with low birth weights had a higher incidence of a number of chronic cardiovascular conditions as adults, including heart disease, hypertension (high blood pressure), diabetes and raised cholesterol. In some societies they are also up to ten times more likely to die prematurely in young adulthood. These relationships were independent of the length of the pregnancy, suggesting that such outcomes were related to growth restriction in the womb rather than premature birth. Barker proposed that poor maternal nutrition during pregnancy could cause genetic changes affecting the development of fetal organs, leading to increased susceptibility to chronic diseases in years to come and ultimately a shorter life span. Experimental studies in animals later confirmed the link between maternal diet and the adult health of the fetus. For example, feeding pregnant rats a low-protein diet throughout their pregnancies was found to cause lifelong elevation of blood pressure in their offspring.

Interestingly, fetuses that are clinically malnourished during the first trimester of development are three times more likely to be obese as adults. A 2003 New Zealand study offered an explanation for this by showing that rats that were undernourished in the womb exhibited both abnormal eating and exercise behaviours as adults. This effect was found to occur independently of nutrition available after birth. The researchers involved contend that lifestyle choices themselves may thus have a pre-natal origin. In contrast, a recent collaborative study between scientists in Britain and Queensland found that high birth weight is linked in later life to an elevated IQ. Such findings could have profound implications for public health policy, suggesting for example that health care funding may be better spent on improving pregnancy care than on chronic conditions manifesting years or decades later.

Further research into these effects has been carried out by Professor Marelyn Wintour, of Monash University in Melbourne. Professor Wintour notes that in Western populations it is rarely a lack of food as such that causes in-utero malnutrition and low birth weights. Rather, these are more commonly associated with placental abnormalities, maternal disease or specific deficiencies in the maternal diet. Vitamin D deficiency during pregnancy for example (common in women who are dark skinned or wear UV-obstructive clothing such as a veil or burka) has been suggested to correlate with the later development of schizophrenia, while low levels of Vitamin A can impair renal (kidney) development. Insufficient concentrations of iron and fatty acids such as omega-3 in the maternal diet have also been linked with an increased adult risk of a variety of conditions, including forms of cancer and leukemia. Almost all such deficiencies are easily preventable or treatable, though according to Professor Wintour, "The most alarming finding is that the time at which the fetus is most vulnerable- early in the pregnancy or around 5-7 weeks- is when the woman may be unaware she is actually pregnant".

Environmental factors also play a role in dictating the future health of the fetus. It is well established that maternal abuse of substances such as alcohol or nicotine can have both immediate and long term effects on factors as diverse as the brain development, immune system, birth weight, attention span and social skills of the offspring. Similar effects may also be seen after gestational exposure to certain drugs (including cocaine) or toxins such as mercury, lead or some pesticides. Other influences are more insidious. Regular in-utero exposure to loud noise, such as that which might occur within a factory workplace, has been found to damage the developing immune system. Low oxygen environments (for example in communities living at high altitudes) can retard in-utero growth, while American studies have suggested a link between maternal exposure to a certain bacterial toxin and later susceptibility of that fetus to Parkinson's disease.

But one of the most important- and to some degree unavoidable- environmental variables is stress. This is commonly studied using sheep, as the lamb normally grows to the same size as a human baby in a relatively long pregnancy, and the development of major organs including the heart and brain is very similar in humans and sheep. To simulate stress in pregnancy, Professor Wintour's team exposed sheep early in their pregnancy to a stress hormone, cortisol, for a short duration. The offspring were later found to develop high blood pressure from four months after birth, which increased in severity as they aged. Kidney development was also impaired. Dr. Julie Quinlivan, working with researchers at the University of Western Australia, found that injecting sheep with stress hormones later in their pregnancies and on a number of occasions produced different effects, including the later development of insulin resistance and diabetes. This suggests that the timing of stressful insults can have varying outcomes.

The duration of exposure to stress is also crucial. Dr. Quinlivan notes, "Basically, if you have a single exposure to stress hormones, the body is very resilient. But if you have repeated exposure to stress, it affects the number of brain cells in a fetus' brain, the growth of the baby, and the development of the thyroid and the immune system, so it has multiple effects". In addition to physical effects such as hypertension or diabetes, abnormal concentrations of cortisol in-utero can also create psychological syndromes. Studies have found that infants exposed to elevated levels of cortisol in the womb- often because their mother was under stress or depressed herself- are at increased risk of depressive disorders throughout childhood, adolescence and adulthood. Such individuals also commonly exhibit cognitive delays and long-term behavioral dysfunction.

Interestingly, the effects of cortisol and other hormones may be ameliorated somewhat by the sex of the fetus. Recent research has suggested that cortisol appears to cross the placenta more easily in female than male fetuses, thus placing women at greater risk of developing those conditions related to excesses of this hormone in later life. More generally, sex differences in response to particular in-utero environments may also be seen because male and female foetuses grow on different schedules.

So what does all this mean to the woman who is pregnant or hoping to become so? Put simply, she should eat well not just from the time the pregnancy is confirmed, but ideally also in the months leading up to conception, so as to avoid any potential deficiencies at a time when the fetus is particularly vulnerable. Such a diet should include lots of fruit, vegetables, bread and cereals, moderate amounts of dairy foods and lean meats, and small quantities of foods high in sugar, salt and fat. While adequate Vitamin A is essential for kidney development as noted above, supplements of this vitamin are not recommended without medical supervision, as these may cause birth deformities. Instead, try increasing the consumption of milk, eggs, green leafy vegetables and fruit. Two servings of fish per week are also recommended for their omega-3 acids, while adequate Vitamin D can be obtained from a daily ten minute exposure of the lower arms and legs to sunshine (though avoid the hours between 11am and 3pm). Iron stores can be boosted by eating red meat in conjunction with foods that enhance iron absorption, such as oranges, broccoli or potatoes.

Recent work by Dr. Phillip Henschke at the Royal Women's Hospital in Melbourne suggests that alcohol should be avoided throughout pregnancy as this can cause changes in brain development even as late as the third trimester. And Professor Wintour notes that if stress cannot be avoided altogether, pregnant women should aim for one hour of relaxation per day to interrupt any hormonal response to stress. Staying away from the sushi probably can't hurt either.

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