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How do cetaceans give birth and feed their young?

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Illustration showing various cetaceans, including baleen whales like the blue whale, fin whale, humpback whale, gray whale, sei whale, northern right whale, and bowhead whale, as well as toothed whales such as the sperm whale, narwhal, beluga, Baird's beaked whale, killer whale, dolphins, and porpoises. Each species is labeled with its scientific name and typical or maximum length, with a size scale in the corner for reference. — cetacean Whales (order Cetacea).

As mammals, cetaceans reproduce via internal fertilization and give birth to live young. Unlike most terrestrial mammals, cetaceans give birth tail first. Typically, a single calf is born following a gestation period that lasts about a year, though some toothed whales may have gestations lasting up to 18 months.12

Regarding feeding, mothers produce extremely rich milk for their offspring, which often contains 50 percent fat. This milk is delivered via paired mammary glands located on the lower abdomen, just forward of the anal-genital slits. Calves are generally weaned between six months and one year of age, though they continue to grow rapidly for several years afterward. In some species, older females may assist in the rearing of young, an adaptation potentially linked to the evolution of menopause in certain toothed whales.13