This study examines the effects of an infant formula containing increased calories, as compared to commercial formulas, when given during the first 6 months of life. It will examine effects on growth, disease progress, immune system, and quality of life of infected infants.

HIV disease in infants often leads to nutritional deficiencies. Providing increased nutrition early in their lives may help the quality of life of children who contract HIV from their mothers.

In order to meet the optimal nutritional needs of HIV-infected infants, it is critical that nutritional intervention begin early. Early nutritional intervention may help reduce the susceptibility to or severity of primary HIV and/or opportunistic infections and add to the quality of life for children perinatally infected with HIV.

[AS PER AMENDMENT 08/29/01: This study population will consist of infants from domestic sites and international sites.] In this double-blind, controlled study perinatally HIV-exposed infants less than 15 days old [AS PER AMENDMENT 08/29/01: "less than 15 days old" has been replaced with: less than 17 days old] at time of study entry are randomized to 1 of 2 arms to receive either concentrated formula or standard formula for 8 weeks after being stratified by gestational age: less than 37 versus greater than 37 completed weeks. At the 8-week visit using a previously determined 8:1 random allocation, 89% of singleton infants [AS PER AMENDMENT 08/29/01: from international sites] with negative HIV-specific tests are discontinued from study treatment and further follow-up. The other 11 percent of these singleton infants with negative HIV-specific tests continue study treatment with open-label standard formula until Week 28 (control group). Singleton infants with positive HIV-specific tests continue on the blinded portion of the study and receive formula as initially assigned until Week 28. For a given multiple birth, if any of the infants at the 8-week study visit are determined to be infected, all the infants from that birth continue their initial blinded treatment assignment until Week 28; if none of the infants are determined to be infected at this time, all the infants from that birth continue study treatment with open-label standard formula until Week 28. All infants assigned to receive study treatment through Week 28 continue study follow-up until 12 months of age. A subset of patients at sites with appropriate resources will participate in a substudy in which measurements of triceps and thigh skinfold thickness and circumference and thigh density DEXA scans are evaluated.

Inclusion Criteria

Children may be eligible for this study if they:

• Are 1 to 17 days old. (This study has been changed. Originally, infants 1 to 15 days old were eligible for this study.)
• Weigh 4 or more pounds.
• Were born to an HIV-positive mother.
• Have a caregiver willing to measure and keep records of infant's food intake.

Exclusion Criteria

Children will not be eligible for this study if they:

• Are breast-fed.
• Have certain disorders, including the inability to feed by mouth, or a life-threatening condition.
• Take medication which affects growth.