HMOs

HMOs commonly refers to Health Maintenance Organizations, a type of managed care organization in the United States. HMOs organize medical services through a network of affiliated providers and emphasize preventive care and cost containment. Members typically receive most services through in-network providers, with lower out-of-pocket costs, but with restrictions such as a primary care physician gatekeeping access to specialists and limited coverage for care received outside the network.

In operation, HMOs contract with a defined group of physicians, hospitals, and other providers. Members usually select a designated primary care doctor who coordinates care and approves referrals for specialists. Financing often relies on negotiated fees or capitation rather than fee-for-service payments. Proponents cite lower premiums and predictable costs, while critics point to restricted choice, potential delays in specialty care, and penalties for out-of-network use.

HMOs can also refer to human milk oligosaccharides, a diverse group of complex carbohydrates found in human milk. Most HMOs are not digested by infants but serve as prebiotics, supporting beneficial gut bacteria and contributing to immune and intestinal development. They occur in hundreds of structures, with variations such as fucosylated or sialylated forms. In infant nutrition, synthesized or bovine-derived HMOs are being studied for their potential to mimic some effects of natural human milk and are included in some fortified formulas, though research and regulatory considerations continue.