LONDON — Britain’s fertility regulator has approved controversial techniques allowing doctors to create babies using the DNA from three people – what it called a “historic” decision to help prevent a small number of children from inheriting potentially fatal diseases from their mothers.

The regulator’s chairwoman, Sally Chesire, called it a “life-changing” moment for families.

The procedures are intended to fix problems linked to mitochondria, the energy-producing structures outside a cell’s nucleus. Faulty mitochondria can result in muscular dystrophy, organ failure and muscle weakness.

Last year, Britain changed its law to permit scientists to modify eggs or embryos before they are transferred into women.