Our Baby News

WHAT IS THE REAL CALORIC COST IF THE MOTHER IS SEDENTARY?

Basal metabolic rate, activity pattern and energy costs of some daily activities were measured in 25 Dutch women throughout pregnancy and in the first year postpartum.

Typical women in this population demonstrated very low basal metabolic needs and very low levels of physical activity.

 The end result was that daily k calorie needs were modest at best.

Basal metabolic requirements at one year postpartum were 1,440 kcal per day; the costs of physical activity were modest.

The conclusions of the researchers in this study were as follows:

For women with sedentary lifestyles, the energy save A during pregnancy and lactation because of decreased physical activity and decreased costs of activities will be limited.

The impact of exercise on the pregnant woman and the fetus has been the source of considerable debate resulting in conflicting recommendations.

Physical fitness enthusiasts have championed maintenance of vigorous activity during pregnancy, whereas others, particularly those concerned with the effects of manual labor, have urged caution.

Historically, traditional advice to women from the obstetric community has been to decrease activity and increase periods of rest during pregnancy, particularly in the third trimester.

Over the past decade, a number of studies have been conducted regarding this issue; unfortunately, most have been of weak scientific method and reflect the bias of the investigators.

In 1982, the National Institutes of Health sponsored a planning workshop dealing with physical activity in pregnancy.

This workshop identified dimensions of research needed, particularly prospective studies regarding both beneficial and adverse effects of exercise in pregnant women.

A review by Mohs and colleagues summarizes nicely the impact of use of addictive drugs on food and liquid intake, taste preference, and body weight.

Observations are also reported for changes in specific nutrient status and metabolism.

For example, heroin addiction can cause hyperkalemia, and morphine use can result in calcium inhibition.

Nutrition-related physiologic aspects, such as impaired gastrin release, hypercholesterolemia, hypothermia, and hyperthermia are also seen with morphine use.

Diabetes decreases sensitivity to and dependence on morphine, protein deprivation produces preferential fat utilization with low cocaine use, and vitamin D deficiency decelerates morphine dependency.

Data suggest that during use and/or withdrawal from nicotine, heroin, marijuana, and cocaine, major changes in food selection and intake occur; these may result in weight gain or weight loss.

There are few consistent effects of prenatal cocaine exposure.

When the offspring of cocaine-using women are compared with the offspring of women not using drugs, the exposed offspring display a broad variety of abnormalities. However, when the offspring of drug-using women are compared with one another, few defects emerge that can be ascribed uniquely to cocaine .

Some reports associate cocaine use with pregnancy complications. One group found increased rates of preterm labor, precipitous labor, and abruptio placentae (premature detachment of the placenta) in a cocaine-using group compared with women who were not exposed to any drugs.

In other studies, however, there was no difference between cocaine users and nonusers in pregnancy, labor, or delivery complications. Other studies have reported that women who used cocaine and who received adequate prenatal care did not differ in the rate of abruptio placentae from non-cocaine-using controls.

Prenatal cocaine exposure also has been associated with decreased length of gestation and increased   rate   of   prematurity.

However,   researchers do not always control for the use of other drugs or for other factors associated with cocaine use and, therefore the effects cannot conclusively be attributed to cocaine.

Although there have been reports of an association between prenatal marijuana exposure and smaller size at birth, these have been offset by reports that found no such effect.

Growth deficits have not been found in studies with long-term follow-up. Similarly, recent data refute earlier reports of physical abnormalities resulting from prenatal marijuana exposure.

Studies of the effects of prenatal marijuana exposure on the brain and on intellectual and behavioral development have been provocative. Researchers studying the electrical activity of the brain during sleep in a subset of newborns found significant differences between marijuana-exposed and non exposed subjects.

Disturbed sleep patterns were still significantly associated with prenatal marijuana exposure in 3-year-old children.

Effects of marijuana exposure on the brain have been found in older children as well. Three-year-old children showed significant effects of first- and second-trimester exposure to marijuana on the composite score of the Stanford-Binet Intelligence Scale  as well as on those portions of the scale that measure short-term memory, verbal reasoning, and abstract/visual reasoning. These children showed the same effects at age 6. Other workers reported on the behavioral development of children who were part of the Ottawa Prenatal Prospective Study.

Fetal Growth Retardation

Fetal growth retardation is often seen in offspring of cigarette smokers . It has been postulated that this is a result of the reduced food intake of the mother, but observations have shown that this is not true ; women smokers often consume more k calories per day than women who do not smoke.

 The growth-retarding impact of smoking appears to be related to the effects of carbon monoxide, nicotine, cyanides, and possibly other compounds on placental perfusion and oxygen transport to the fetus. It is also likely that efficiency of k calorie utilization is reduced in women who smoke.

Whether or not encouraging greater weight gain among smoking mothers will increase infant size is a question that has been inadequately addressed. However, several reports have suggested that greater prenatal weight gain is directly related to greater infant birth weight in this population.

In 1992, 16.9% of U.S. mothers reported having smoked during pregnancy. Smoking was more common in white mothers than in blacks. In both groups, there has been a small reduction in the level of smoking since 1989. Smoking rates for Asian women are generally very low; this is also true of Hispanic mothers. In both cases, the level of smoking was observed to be less in foreign-born than U.S.-born mothers.

Heavy metals. A number of “contaminants” are found in food, and some of these may adversely affect pregnancy course and outcome if consumed in sufficient amounts.

Most heavy metals are embryotoxic, but only mercury, lead, cadmium, and possibly nickel and selenium have been implicated in this regard.

Lead toxicity has long been known to be associated with abortion and menstrual disorders.

Evidence as to whether lead is teratogenic is conflicting; whereas some authors report a correlation between atmospheric lead levels and congenital malformations, others deny these associations.

In sheep, prenatal lead exposure has also been shown to affect the offspring’s learning ability.

Probably the earliest instance of massive, unplanned exposure of a localized population to an environmental toxicant occurred in 1953, in and around Minamata, a town located on a bay in southern Japan.

Unusual neurological problems (e.g., mental confusion, convulsions, and coma) began afflicting villagers.

The teratogenicity of common food additives is largely unknown in human situations.

Metabolites of cyclamate and red dye no. 2 reportedly damage developing rat embryos, but both of these additives have now been banned from use in the U.S. food supply.

Artificial sweeteners have come under careful scrutiny in the past few years. Neither saccharin nor cyclamate has proven to be teratogenic in rodents.

Kline teal reported that the incidence of spontaneous abortion in a human population was not associated with ingestion of any sugar substitute.

However, because saccharin has been shown to be weakly carcinogenic in rats, moderation in its use seems appropriate.

This is especially true for the woman of reproductive age, since studies in rats indicate that saccharin is most effective as an initiator of bladder cancer when the mother is exposed to high doses before pregnancy and the offspring are exposed in utero and throughout their lives. Because saccharin can also markedly promote or enhance the potential of other carcinogens in rats, another basis for moderation in use is available.

Herbal teas and herbal remedies have been part of folk medicine for centuries.

There are currently more than 400 distinct herbs and spices commercially available to use either alone or in blended mixtures as tea.

Many commercially prepared drugs originated from plants.31’74 Consumers interested in “natural food” often turn to these products; other consumers looking for alternatives to caffeine-containing beverages often find herbal teas attractive.

Pregnant women should be discouraged from unlimited consumption of herb teas.

The major reason for this is that the composition and safety of most of them is unknown.

Rather than seek FDA approval, most manufacturers of herbal tea preparations stopped marketing the mixtures as medicine and simply list the ingredients on the label.

In 1983 the FDA officially designated 28 plants as unsafe to consume and wrote,

In 1980 the Food and Drug Administration (FDA) warned pregnant women to restrict or even eliminate consumption of coffee based on studies showing teratogenic effects in rodents.

18 Although this advisory remains in effect, the implications of caffeine consumption during pregnancy remain controversial.

The results of studies in rodents indicate that caffeine, when administered in large single doses has teratogenic effects.

In addition to fetal resorptions, the most commonly seen malformations are those of die limbs and digits, as well as cleft lips and palates. Such malformations are observed, however, only in relatively high doses.

Teratogenic effects usually appear only at doses high enough to cause toxicity in the mother and far higher than those consumed by humans, even those who drink large amounts of coffee. For example, a woman weighing 60 kg would have to drink about 10 to 14 cups of coffee in one sitting to achieve plasma caffeine concentrations comparable to those associated with teratogenic effects in the rat. Animal studies in which more moderate doses were administered over the course of a day (to mimic the typical pattern of human caffeine intake) have not shown teratogenic effects.