Introduction

Lipids play numerous and diverse roles in the development of the fetus. Fatty acids are required for the synthesis of cell membranes, which are a prerequisite for tissue growth, for the synthesis of second messengers and for generation of energy reserves in adipose tissue. Cholesterol is also required for tissue growth, and for the synthesis of steroid hormones. This chapter discusses how the physiology of the mother adapts to meet the demands of the fetus for fatty acids and cholesterol, the functions of these lipids in the development of specific tissues and the consequences of deficits in lipid accretion for tissue function, with a specific focus on long-chain polyunsaturated fatty acids (PUFAs).

Lipids and fetal development

Fat accumulation and birthweight

In humans, fetal fat accretion into adipose tissues begins between 15 and 20 weeks gestation, but increases exponentially from about 30 g at 30 weeks gestation to 430 g at term (Southgate and Hay 1976). The early phase of adipogenesis is associated with deposition of subcutaneous fat, while visceral fat accumulation occurs during the mid second and third trimesters (Poissonnet et al. 1984). Such deposition may serve to provide insulation during early life, which is important in the absence of body hair (Pawlowski 1998), and it is notable that in nonhuman primates fat deposition begins after birth (Adolph and Heggeness 1971, Lewis et al. 1983). Prenatal accumulation of adipose tissue may also serve to generate a nutrient reserve to survive infancy (Kuzawa 1998, Correia et al. 2004).