During development, the human fetus accrues the highest proportion of fat of all mammals. Precursors of fat lobules can be found at week 14 of pregnancy. Thereafter, they expand, filling with triacylglycerols during pregnancy. The resultant mature lipid-filled adipocytes emerge from a developmental programme of embryonic stem cells, which is regulated differently than adult adipogenesis.

Fetal triacylglycerol synthesis uses glycerol and fatty acids derived predominantly from glycolysis and lipogenesis in liver and adipocytes. The fatty acid composition of fetal adipose tissue at the end of pregnancy shows a preponderance of palmitic acid, and differs from the mother. Maternal diabetes mellitus does not influence this fatty acid profile. Glucose oxidation is the main source of energy for the fetus, but mitochondrial fatty acid oxidation also contributes. Indirect evidence suggests the presence of lipoprotein lipase in fetal adipose tissue. Its activity may be increased under hyperinsulinemic conditions as in maternal diabetes mellitus and obesity, thereby contributing to increased triacylglycerol deposition found in the newborns of such pregnancies. Fetal lipolysis is low. Changes in the expression of genes controlling metabolism in fetal adipose tissue appear to contribute actively to the increased neonatal fat mass found in diabetes and obesity. Many of these processes are under endocrine regulation, principally by insulin, and show sex-differences. Novel fatty acid derived signals such as oxylipins are present in cord blood with as yet undiscovered function. Despite many decades of research on fetal lipid deposition and metabolism, many key questions await answers.

在发育过程中，人类胎儿在所有哺乳动物中积累的脂肪比例最高。妊娠第 14 周可发现脂肪小叶前体。此后，它们膨胀，在怀孕期间充满三酰基甘油。由此产生的成熟的充满脂质的脂肪细胞来自胚胎干细胞的发育程序，其调节方式与成人脂肪生成不同。

胎儿三酰基甘油合成使用主要来源于肝脏和脂肪细胞中的糖酵解和脂肪生成的甘油和脂肪酸。妊娠末期胎儿脂肪组织的脂肪酸组成以棕榈酸为主，与母亲不同。母体糖尿病不影响这种脂肪酸谱。葡萄糖氧化是胎儿的主要能量来源，但线粒体脂肪酸氧化也有贡献。间接证据表明胎儿脂肪组织中存在脂蛋白脂肪酶。在高胰岛素血症条件下，如在母体糖尿病和肥胖症中，其活性可能会增加，从而导致在此类妊娠的新生儿中发现的三酰基甘油沉积增加。胎儿脂肪分解低。胎儿脂肪组织中控制新陈代谢的基因表达的变化似乎对糖尿病和肥胖症中发现的新生儿脂肪量增加有积极作用。许多这些过程都受到内分泌调节，主要是通过胰岛素，并且表现出性别差异。脐带血中存在新的脂肪酸衍生信号，如氧脂素，其功能尚未被发现。尽管对胎儿脂质沉积和代谢进行了数十年的研究，但许多关键问题仍有待解答。