Enteral feeding of intrauterine growth restriction preterm infants: theoretical risks and practical implications

Abstract

Intrauterine growth restriction (IUGR) infants are thought to have impaired gut function after birth secondary to intrauterine redistribution of the blood flow, due to placental insufficiency, with a consequent reduction of gut perfusion. For this reason, infants complicated by IUGR have been considered at higher risk of feeding intolerance. Postnatal evaluation of splanchnic perfusion, through Doppler of the superior mesenteric artery, and of splanchnic oxygenation, through near infrared spectroscopy measurements, may be useful in evaluating the persistence (or not) of the redistribution of blood flow occurred in utero. IntroductionThe term intrauterine growth restriction (IUGR) indicates the presence of a pathological process occurring in utero that inhibits fetal growth as documented by at least two fetal intra-uterine growth assessments. Fetal growth restriction (FGR) or intrauterine growth restriction is defined as the failure of the fetus to achieve its growth potential and represents one of the most debated issues in obstetrics, being in continuous search for improvement in terms of definition, classification, diagnosis and management. 1 IUGR is an important problem in perinatal medicine. It is the second cause of perinatal mortality after prematurity. The two conditions are often associated in case of iatrogenic prematurity. Fifty-two per cent of stillbirths are associated with IUGR and 10% of perinatal mortality cases in Europe are the consequence of unrecognized severe growth restriction. In developed countries, 3-7% of newborns are classified as IUGR. 2 The most common cause of IUGR is the placental obliterative vasculopathy that reduces nutrients and oxygen supply to the fetus; the causes include, but are not limited to, maternal malnutrition, maternal hypertension and idiopathic placental insufficiency. Placental insufficiency may be characterized by blood flow redistribution to the vital organs (brain, myocardium, and adrenal glands), while other organs, including the gastrointestinal tract, are deprived from sufficient blood flow. These fetuses are at increased risk of hypoxia, hypoglycemia and acidosis and also spontaneous preterm delivery. 3,4 The intrauterine growth restriction fetus: detection and monitoring Fetal monitoringThe main directions towards assessing fetal growth state can be clinical (e.g. the assessment of symphyseal-fundal height) and paraclinical (e.g. ultrasound biometry).Commonly used clinical methods for estimating fetal size are clinical palpation, fundal height measurement and ultrasonic fetal biometry. Serial ultrasound biometric recordings may be able to identify the fetus that does not reach its growth potential. Ultrasound must be considered the method of choice as it is highly reliable and reproducible. 5 The ultrasound limit for SGA or FGR is arbitrarily fixed at an estimated fetal weight (EFW) or abdominal circumference (AC) under the 3 rd , 5 th , 10 th percentile or below -2 Standard Deviation (SD) from the population standard or reference. 6 When IUGR is t...

Comparison of neonatal outcomes of small for gestational age and appropriate for gestational age preterm infants born at 28–36 weeks of gestation: a multicentre study in Ethiopia

“… 28 The increased risk of NEC might be associated with immature gut development that has resulted from intrauterine chronic fetal hypoxia and consequent cardiovascular redistribution of blood flow away from the gastrointestinal tract to vital organs. 29 …”

Neonatal Morbidities of Fetal Growth Restriction: Pathophysiology and Impact

“…NEC is predominantly seen in infants who are born preterm, but late preterm infants are more likely to develop NEC if they were growth restricted (48). It is likely that i n utero chronic fetal hypoxia and subsequent cardiovascular redistribution of blood flow away from the gastrointestinal tract contribute to immature gut development (49). FGR newborns, especially with abnormal flows in the umbilical artery prior to birth, are shown to have more feed intolerance when compared to their well-grown preterm counterparts (50).…”

Perinatal Outcomes of Fetal Growth Restriction, Classified According to the Delphi Consensus Definition: A Prospective Observational Study

“…FGR has been associated with increased risk of perinatal and neonatal morbidities [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The conventional definition of FGR is based on estimated fetal weight < 10 th centile for gestation.…”