As far as we know, there are no data from studies indicating whether, in chronically undernourished populations, nutritional and health interventions during the period of rapid pubertal growth are capable of correcting previous defects resulting from chronic malnutrition at earlier ages.
It would also be very important to determine whether interventions during that period are more effective than those carried out during periods of slower growth. Nor are there studies demonstrating whether or not there is a relationship between a woman’s nutritional status during puberty and adolescence and the development of the internal diameters of the pelvis.
The possible obstetric importance of nutrition, in terms of dystocia and cephalopelvic disproportion, is unknown, although obstetricians in developing countries consider that women’s physical immaturity caused by chronic malnutrition may contribute to these perinatal complications.
The evaluation of food supplementation and health-promotion programs for school-age pubertal girls should be subject to controlled assessment. If the pubertal period is favorable for correcting previous growth and development defects, interventions at this age would be a priority so that women reach reproductive age in optimal nutritional conditions.
This would lead to a marked reduction in obstetric and perinatal risk. Theoretically, these interventions should be more effective than those carried out during pregnancy, especially if one takes into account that their benefits would be more lasting and that the difficulty of changing intake patterns during pregnancy in traditional societies is well known.
Pre- and Perinatal Health, Energy Balance and Physical Activity
Both in childhood and adulthood, a certain level of physical activity is beneficial, provided that it does not lead to negative energy balances and loss of lean body mass.
On the other hand, sedentary behavior and physical inactivity produce metabolic and physiological alterations, with the resulting functional deterioration and lower efficiency in nutrient utilization. The problem is that this has not been demonstrated in pregnant and lactating women, even though there are data on women in primitive societies who remain active until the end of pregnancy without any harm.
It has also been indicated that food supplementation for undernourished pregnant women improves both maternal and fetal condition, despite the fact that the efficiency of energy use in terms of the child’s weight gain is very low.
It is possible that this favorable effect is due to the correction of a negative energy balance. This interpretation, not necessarily correct, has suggested that the same result could be achieved without changing energy intake if the pregnant woman’s physical activity is reduced.
There is a certain tendency to generalize this practice, although the literature suggests that only severe and excessive physical activity may be harmful in this condition. It has not been scientifically demonstrated that rest is beneficial for pregnant women under non-pathological conditions or in the absence of negative energy balance.
In theory, muscular exercise should be beneficial because of its metabolic effects, because it increases muscle tone, and because it improves cardiorespiratory capacity, among other effects known in non-pregnant conditions.
On the other hand, it is possible that acute periods of negative energy balance may result in lipolysis causing ketonemia and ketonuria, which could be harmful to the fetus.
It is known that the metabolism of pregnant women changes in order to increase the contribution of fat substrate to the maintenance of energy balance. This phenomenon may result in higher levels of ketone bodies than in non-pregnant women under similar conditions of negative energy balance.
It may be that the effect of energy supplementation occurs through the suppression of episodes of ketonemia. If so, the detection of ketone bodies in the urine of pregnant women could be a useful and simple means of identifying those who would benefit from nutritional and lifestyle measures aimed at avoiding negative energy balance.
The creation of centers intended to provide comprehensive care for low-income and undernourished pregnant women, increasing their intake and encouraging them to reduce their physical activity, appears to result in children with better birth weight and fewer obstetric complications.
If physical activity leads to better cardiorespiratory capacity and better muscle tone, while also inducing greater efficiency in food utilization, it could be more beneficial than sedentary behavior. This would apply both under the conditions previously described and in everyday family life, provided that an adequate energy balance is ensured.
The usefulness of detecting ketone bodies in the urine of physically active women or sedentary women throughout pregnancy, as a measure for monitoring negative energy balance, requires validation.
