Consequences of malnutrition in pregnancy

CONSEQUENCES OF MALNUTRITION IN PREGNANCY

Introduction

  • Malnutrition-meaning both inadequate and excessive intakes of nutrients, may affect pregnancy in several ways.
  • The fertilized egg may die at an early stage (i.e. embryo loss) or later, in pregnancy the foetus may develop incorrectly and die; it may then be resorbed in uterine, expelled before full-term (abortion) or carried to full term (still birth).
  • Less severe mal nutrition may reduce the birth weight of young and the viability of small offspring may be diminished by their lack of strength or by their inadequate reserves (eg. of fat).

Effect on the young

  • Deficiencies of individual nutrients on pregnancy must be severe to cause the death of foetuses; proteins and vitamin-A are the nutrients most likely to be implicated, although deaths through iodine, calcium, riboflavin and pantothenic acid deficiencies have also been observed.
  • Congenital deformities of nutritional origin often arise from vitamin-A deficiency, which causes eye and bone malformations in particular.
  • Iodine deficiency causes goiter in the unborn pigs, wherein it has been observed to result in a complete lack of hair in the young.
  • Hairlessness can also be caused by an inadequate supply of riboflavin during pregnancy.
  • Copper deficiency in the pregnancy ewe leads to the condition of sway back in the lamb.
  • In the early stage of pregnancy, when the nutritional demands of the embryo are still insignificant, the energy intake of the mother may influence embryo survival.
  • There is evidence that in sheep and pig both very low and very high intakes of energy at this stage may be damaging, especially in females which is in poor condition at mating.
  • The probable cause is a disturbance of the delicate hormone balance required at this time for implantation of the embryo.
  • In mid pregnancy, the nutrient requirements of the foetus are still low, but the placenta must grow at this time; if the growth of placenta is restricted by under nutrition it will be unable to nourish the foetus adequately in the final stage of pregnancy, and birth weight will be reduced.
  • For sheep and pig a common recommendation is that feeding for the first two-thirds of pregnancy should be at about the maintenance level.
  • In the last one-third of pregnancy, the requirements of the foetus increases rapidly.
  • Variations in birth weight of nutritional origin are usually a reflection of the energy intake of the mother during later stage of pregnancy.
  • Young animals should be born with reserves of mineral elements, particularly iron and copper and of vitamin-A, D and E, because the milk, which may be the sole item of diet for a time after birth, is frequently poorly supplied with the nutrients.
  • With regard to iron, it appears that if the mother is herself adequately supplied and is not anaemic, the administration of extra iron will have no influence on the iron reserves of the new born.
  • The copper and fat soluble vitamin reserves of the newborn are more susceptible to improve through the nutrition of the mother.

Effect on the mother

  • The high priority of the foetus for nutrients mean that the mother is more severally affected directly to deficiencies.
  • The foetus has a high requirement for carbohydrate and by virtue of its priority it is able to maintain the sugar concentration of its own blood at a level higher than that of the mother.
  • If the glucose supply of the mother is sufficient her blood glucose may fall considerably, to levels at which nerve tissues (which rely on carbohydrate for energy) are affected.
  • This occurs is sheep in the condition known as pregnancy toxaemia, which is prevalent in ewes in the last month of pregnancy.
  • Affected animals will become dull and lethargic, loose their appetite and show nervous signs such as trembling and holding the head at an unusual angle, in animals showing these signs the mortality rate may be as high as 90%.
  • The disease occurs most frequently in ewes with more than one foetus - where its alternative name of ‘twin lamb disease' - and is most prevalent in times of food shortage and when the ewes are subjected to stress in the form of inclement weather or transportation.
  • Blood samples from affected animals usually show, in addition to hypoglycaemia, a marked rise in ketone content and an increase in plasma free fatty acids.
  • In the later stages of the disease the animal may suffer from metabolic acidosis and renal failure.
  • The main predisposing factors in pregnancy toxaemia are the high requirement of the foetus for glucose and possible fall in the carbohydrate supply of the mother, which may arise through food shortage or through a decline in appetite in late pregnancy.
  • An additional factor is that increased production of cortisol by the adrenal cortex in response to stress may reduce the utilisation of glucose.
  • The disease has been treated by the injection of glucose, by feeding with substances likely to increase blood glucose levels, or by hormone therapy.
  • The condition can be prevented by ensuring an adequate food supply in late pregnancy and by using food which supply glucose or its precursors rather than acetate.
Last modified: Thursday, 10 November 2011, 12:20 PM