Abstract 1651 Poster Session III, Monday, 5/3 (poster 83)

Background: In the first days of life, breast-fed infants consume minimal amounts of milk (13±16 and 40±23 ml/kg/d on day 1 and 2 respectively) (Casey CE et al, AJDC, 1986;140:933-6); in theory, this may be explained by substrate limitation (limited milk output) and/or by self-limitation (through low appetite and/or suck-swallow competency). The spontaneous milk intake of unrestricted formula-fed infants has not been studied to date.

Objective: To evaluate the spontaneous formula intake of unrestricted formula-fed infants over the first 48 hours of life.

Hypothesis: 1) Spontaneous formula intake of unrestricted infants is much higher than the published values for breast-fed infants. 2) Spontaneous formula intake correlates positively with gestational age or birthweight.

Design: Design: We studied 27 healthy, term (38-41 weeks gestation) appropriate for gestational age (AGA) infants fed formula ad-libitum. All infants were born after uncomplicated pregnancy and labor, and by vaginal vertex delivery. Obstetrical analgesia was epidural bupivacain in all cases. Apgar scores were >7 at 1 and 5 minutes. All infants were fed the same cow-milk based formula by maternal choice, offered ad libitum every 4 hours. Intake was calculated from the measurement of the formula volume in the feeding bottle before and after feeding. Backward stepwise multiple regression was used to study the role of selected factors on formula intake. Results were expressed as mean±SD, and a p value of <0.05 was considered significant.

Results: Formula feeding was 18.5±9.6 ml/kg weight/d on day one of life, increasing to 42.2±14.2 ml/kg weight/d on day 2 of life, very similar to published values in breast-fed infants. In multiple regression, only the age at first feed affected the first day intake. Neither birthweight (or gestational age), Apgar scores, or 24 hour weight loss were significant independent variables. In contrast, the second day intake was positively affected by the first day intake, and (contrary to the hypothesis) negatively affected by the infant birthweight. There was no significant correlation between weight loss and formula intake both on day 1 and on day 2.

Conclusion: Unrestricted formula-fed for infants have a relatively low formula intake on the first 2 days of life. These low levels of intake are strikingly similar to those reported for breast-fed infants; Paradoxically, within this group of term, AGA infants, the larger the infant, the smaller the second day intake/Kg body weight is.

Speculation: Low enteral intake in unrestricted formula-fed infants on the first 2 days of life is possibly due to lower appetite and/or thirst, decreased sucking and swallowing competency, or decreased alertness level.