Prenatal and postnatal development are closely related to healthy maternal conditions that allow for the provision of all nutritional requirements to the offspring. In this regard, an appropriate supply of fatty acids (FA), mainly n-3 and n-6 long-chain polyunsaturated fatty acids (LCPUFA), is crucial to ensure a normal development, because they are an integral part of cell membranes and participate in the synthesis of bioactive molecules that regulate multiple signaling pathways. On the other hand, maternal obesity and excessive gestational weight gain affect FA supply to the fetus and neonate, altering placental nutrient transfer, as well as the production and composition of breast milk during lactation. In this regard, maternal obesity modifies FA profile, resulting in low n-3 and elevated n-6 PUFA levels in maternal and fetal circulation during pregnancy, as well as in breast milk during lactation. These modifications are associated with a pro-inflammatory state and oxidative stress with short and long-term consequences in different organs of the fetus and neonate, including in the liver, brain, skeletal muscle, and adipose tissue. Altogether, these changes confer to the offspring a higher risk of developing obesity and its complications, as well as neuropsychiatric disorders, asthma, and cancer. Considering the consequences of an abnormal FA supply to offspring induced by maternal obesity, we aimed to review the effects of obesity on the metabolism and bioavailability of FA during pregnancy and breastfeeding, with an emphasis on LCPUFA homeostasis.

Background: A healthy maternal diet must consider an appropriate supply of long-chain polyunsaturated fatty acids (LCPUFAs) precursors to ensure adequate growth and development of the fetus. In this regard, n-6 PUFAs, predominantly linoleic (C18:2 n-6, LA) and arachidonic acid (C20:4 n-6), have a central role in the development of the central nervous system because they are part of the membrane structure and participate in the metabolism and signal transduction of cells. Nevertheless, they can also be transformed into inflammatory metabolites promoting the pathogenesis of cardiovascular diseases, cancer, and autoimmune or inflammatory conditions. In modern westernized societies, there is a high dietary consumption of foods rich in n-6 PUFAs which could have detrimental consequences for the fetus and neonate due to excessive exposure to these fatty acids (FAs). Objective: To summarize the evidence of maternal, placental, and fetal alterations that an excessive intake of n-6 polyunsaturated FAs (PUFAs), LA, and AA), could produce during pregnancy. Methods: A thorough review of the literature regarding the effects of n-6 PUFAs during pregnancy and lactation including in vivo and in vitro models, was carried out using the PubMed database from the National Library of Medicine-National Institutes of Health. Results: An elevated intake of n-6 PUFA, specifically LA, during pregnancy influences children's motor, cognitive, and verbal development during infancy and early childhood. Similarly, they could harm the placenta and the development of other fetal organs such as the fat tissue, liver, and cardiovascular system. Conclusion: Maternal diet, specifically LA intake, could have significant repercussions on fetal development and long-term consequences in the offspring, including the possibility of future metabolic and mental diseases. It would be necessary to focus on the prevention of these alterations through timely dietary interventions in the target population.

Efecto de la suplementación con omega-3 durante la gestación y la lactancia sobre la composición de ácidos grasos de la leche materna en los primeros meses de vida: una revisión narrativa Effect of omega-3 supplementation during pregnancy and lactation on the fatty acid composition of breast milk in the first months of life: a narrative review