This systematic review and meta-analysis aim to summarize the effects of maternal undernutrition or overnutrition during pregnancy on fetal weight and morphometric measurements during pregnancy, at birth, and postnatal period in sheep. After completing the search, selection, and data extraction steps, the measure of effect was generated by the individual comparison of each indicator with the average of the control and treated group (undernutrition or overnutrition) using the DerSimonian and Laird method for random effects. Subgroup analyses were also performed for lambing order, litter size, sex, as well as level, timing, and duration of the intervention. Fetal weight during the first third of pregnancy was not affected by maternal undernutrition or overnutrition. On the other hand, undernutrition in the second and last third of gestation reduces the weight of the lamb both during pregnancy, at birth, and during the postnatal period, requiring at least 120 postnatal days to achieve the same weight as its contemporaries in the control treatment. However, this reduction in weight is not accompanied by reductions in morphometric measurements, demonstrating that the animals were lighter, but of equal size. In overnutrition, there is an increase in fetal weight in the second third of gestation. However, in the last third of the gestational period, there are no differences in fetal weight for the multiparous subgroup, but it was reduced in primiparous ewes. There are no effects of overnutrition on birth weight; however, this result is highly heterogeneous. Thus, maternal nutrition of ewe during pregnancy has effects on fetal and postnatal weight, but not on size. Furthermore, the effects of undernutrition are more homogeneous while overnutrition showed heterogeneous responses.

中文翻译：

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羊的胎儿编程：对羔羊产前和产后发育的影响。

本系统评价和荟萃分析旨在总结母体在妊娠期间营养不良或营养过剩对羊妊娠、出生和产后期间胎儿体重和形态测量的影响。在完成搜索、选择和数据提取步骤后，使用 DerSimonian 和 Laird 随机效应方法，通过将每个指标与对照组和治疗组（营养不良或营养过剩）的平均值进行个体比较，生成效应量度。还对产羔顺序、窝产仔数、性别以及干预的水平、时间和持续时间进行了亚组分析。怀孕前三分之一的胎儿体重不受母亲营养不足或营养过剩的影响。另一方面，妊娠后三分之一和最后三分之一的营养不足会降低怀孕、出生和产后羔羊的体重，至少需要产后 120 天才能达到与对照组同时代的羔羊相同的体重。然而，这种体重减轻并没有伴随着形态测量的减少，这表明动物更轻，但大小相同。在营养过剩的情况下，妊娠后三分之一的胎儿体重会增加。然而，在妊娠期的最后三分之一，经产亚组的胎儿体重没有差异，但初产母羊的体重有所减少。营养过剩对出生体重没有影响；然而，这个结果是高度异质的。因此，母羊在怀孕期间的母体营养对胎儿和产后体重有影响，但对大小没有影响。此外，营养不足的影响更为均匀，而营养过剩则表现出不同的反应。