Long chain polyunsaturated fatty acids, docosahexanoic acid (DHA) and arachidonic acid (AA) accumulate in large quantities in brain during the last trimester of pregnancy and play a role in modulating the structure and function of neuronal membranes. Human milk (BM) contains DHA and AA, however infant formulas are devoid of DHA and AA and only contain their 18-carbon precursors, linoleic and linolenic acid. The ability to elongate and desaturate these fatty acids is limited in preterm infants. We hypothesized that preterm infants fed formula would have slower brain stem maturation compared to preterm infants fed BM as manifested by a delayed maturation of the auditory brainstem response (ABR). In an ongoing prospective study involving sequential measurement of ABR in preterm infants, 35 infants ranging from 28-32 wk gestational age were identified who showed a general pattern of normal auditory maturation, i.e. decreasing absolute latencies, during the first week. All infants had a repeat ABR 2 wk after initial ABR. The decreases in wave V and III latency, I-V interval, and III-V interval were calculated. Charts were reviewed to determine intake during that 2 wk interval. Three infants receiving parenteral alimentation and 2 infants receiving both formula and BM were excluded. Fourteen infants received BM and 16 received formula. Data on these 30 infants suggested faster maturation of the ABR in infants fed BM as compared to infants fed formula (see table). These observations are consistent with animal data implicating the importance of DHA and AA for early brain development.

Table 1 No caption available.
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