Steroid chemists often refer to the 1930s as the Decade of the Sex Hormones, when the molecular structures of certain sex hormones were determined and first introduced to medical practice as drugs. Russell Marker achieved the first practical synthesis of the pregnancy hormone, progesterone, by what now is known as the "Marker Degradation." Produced from starting material in a species of Mexican yam, Marker’s progesterone eventually became the preferred precursor in the industrial preparation of the anti-inflammatory drug cortisone. Important research on sex hormones continued in Mexico, leading to the synthesis of the first useful oral contraceptive in 1951.