<qa>  What is the product of defective deep placentation?Introduction: uteroplacental ischemia may cause preterm birth, either due to preterm labor, preterm premature rupture of membranes, or medical indication in the presence of preeclampsia or fetal growth restriction. Uteroplacental ischemia is the product of defective deep placentation, that is a failure of invasion and transformation of the spiral arteries by the trophoblast. It has been reported that the failure of normal placentation generates a series of clinical abnormalities nowadays called deep placentation disorders; they include preeclampsia PE, fetal growth restriction FGR, preterm labor PL, preterm premature rupture of membranes PPROM, in utero fetal death and placental abruption. Strategies to prevent deep placentation disorders have been just partially effective. Docosahexaenoic acid DHA is an essential fatty acid of the family of long chain polyunsaturated fatty acids LC-PUFAs or omega-3 fatty acids. Early reports, suggested that a LC-PUFAs rich diet reduces the incidence of deep placentation disorders. Recent randomized controlled trials are inconsistent to show the benefit of DHA supplementation during pregnancy to prevent deep placentation disorders; but most of them showed that DHA supplementation was associated to lower risk of early preterm birth. 