Malcolm Potts, a physician, reproductive scientist and contraceptive evangelist who helped develop and promote the device most frequently used to perform surgical abortions, and who spent more than half a century directing programs that provide reproductive health services to women in developing countries, died on April 25 at his home in Berkeley, Calif. He was 90.

The cause was Alzheimer’s disease, said his stepdaughter, Madison Iler.

Although he didn’t identify himself as such, Dr. Potts was essentially a neo-Malthusian. Like Thomas Robert Malthus, the economist of the late 18th and early 19th centuries. he saw population control as critical to preventing war, famine and environmental collapse, particularly in Africa, where for decades he oversaw women’s health programs, first as medical director of the International Planned Parenthood Federation and then as president of Family Health International, another global organization. He felt that women’s ability to control their own reproductive lives was crucial to that aim — an enormous challenge in the conservative countries he served.

“Malcolm felt we were heading for catastrophe if we didn’t do a better job in family planning,” said Stefano Bertozzi, a former dean at the University of California, Berkeley School of Public Health, where Dr. Potts held an endowed chair in population and family planning. The two met when they were working on H.I.V. prevention in Africa for different organizations.

“He was a ferocious ally for women having unfettered access to the tools they needed to manage their own fertility,” Dr. Bertozzi said in an interview.

The British-born Dr. Potts was rumpled, tweedy and irreverent. He was of a generation that did not pander to political correctness, and he had a collection of ties printed with condoms. He was also one of Berkeley’s most popular professors. His classes on human sexuality, at which he dispensed policy points, naughty anecdotes and common sense, were filled to overflowing. Dr. Bertozzi called him the Bernie Sanders of Berkeley.

Dr. Potts, fourth from left, at a commencement ceremony at the University of California, Berkeley School of Public Health. One of Berkeley’s most popular professors, he had a collection of ties printed with condoms, and his classes on human sexuality were filled to overflowing.Credit…via U.C. Berkeley