Fetal programming in sheep: Effects on pre- and postnatal organs and glands development in lambs

The present systematic review and meta-analysis aim to summarize the effects of maternal undernutrition or overnutrition during pregnancy on the absolute weight and relative weight of the organs (liver, kidneys, heart, spleen, and lung) and glands (adrenal, pancreas, and thyroid) measured during gestation, birth and the postnatal period in lambs. After completing the search, selection, and data extraction steps, the measure of effect was generated by the individual comparison of each variable response compared with the average of the control and treated group (undernutrition or overnutrition) using the DerSimonian and Laird method for random effects. The liver was the organ most affected by maternal undernutrition, as the absolute weight of the liver was reduced during pregnancy, birth, and the postnatal period. The extent of this effect is related to the duration of the intervention. Reductions in the absolute fetal weight of the lungs and spleen have also been observed. No change in organs weight were observed when the results were expressed as relative weight. For overnutrition, the fetal weight of the liver was reduced to both absolute and relative values. In contrast, the relative weight of the kidneys has been increased. For the glands analyzed, no changes in weight were observed in either scenario (absolute or relative weight). Thus, the organs are more likely to suffer weight changes, especially during pregnancy, as a result of maternal nutrition. However, this change in organ weight seems to be closely related to the reduction in body weight of the progeny as a whole.