In 1976, the Harvard School of Public Health and two other major medical institutions started a study on nurses that has become one of the largest and longest research efforts ever conducted on women’s health. They have so far enrolled more than 275,000 participants.

On Thursday, the Harvard school announced an even more ambitious women’s health study, one that aims to enroll a million women over a decade.

The new ingredients allowing the huge scale: Apple’s iPhones, apps and money.

Harvard’s new study is just one of three new large research efforts that Apple is working on with leading academic research centers an d health organization s. Together, the studies, which Apple is paying for, show how the Silicon Valley giant and its popular products are reshaping medical research.

To enroll in clinical trials, patients have often had to travel to medical centers to be briefed by researchers and fill out the study paperwork in person. Many studies also follow patients only intermittently, in periodic surveys and visits to hospitals.