Does intravenous fish oil affect the growth of extremely low birth weight preterm infants on parenteral nutrition?

Background & Aims: Long chain n-3 fatty acids (n-3 LCPUFA) play a pivotal role during central nervous system development and the provision of docosahexaenoic acid (DHA) is recommended for the preterm infant. However, there are concerns that oral fish oil, which is a good source of DHA, may adversely affect growth of preterm infants, as it decreases arachidonic acid (ARA). It has been about ten years since fish oil was added to the fat blend of intravenous (IV) lipid emulsions (LE) but information on growth and other clinical outcomes of preterm infants is still scarce. We studied the effect of fish oil containing IV LE vs standard IV LE on growth in a large cohort of preterm infants who received routine parenteral nutrition (PN).

Methods: We retrospectively reviewed growth data of 546 preterm infants with a birth weight (BW) < 1250 g consecutively admitted to our NICU between Oct-2008 and Jun-2017 who received PN starting from the first day of life. Individual patients received only one of 5 commercially available IV LE. For the purpose of this study we grouped the patients who received the fish oil containing LE (IV-FO) and those who received conventional LE (CNTR). We compared PN and enteral nutrition (EN) intakes, and growth from birth to 36 weeks post-menstrual age (W PMA).

Results: Demographics, birth data and the incidence of the main complications of prematurity were similar between the two groups (IV-FO: n = 240, Gestational age (GA) 197 ± 16 d, BW 942 ± 181 g; CNTR: n = 237, GA 199 ± 17 d, BW 960 ± 197 g). No difference was found in PN and EN energy and macronutrient intakes from birth to 36W PMA, as well as in the proportion of human milk to infant milk formula. Weight gain from the regained BW to 36W PMA was slightly but significantly higher in IV-FO group: 17.3 ± 2.8 and 16.8 ± 2.7 g∙kg∙d, IV-FO and CNTR respectively (p = 0.03). There was no difference in length gain and head growth nor in body size at 36W PMA between the two groups.

Conclusions: The use of IV fish oil did not negatively affect weight gain in a cohort of preterm infants. Large randomized controlled trials are needed to assess the effect of IV fish oil on the complication of prematurity and on selected domains of infant development.