During the past three decades, twinning in dairy cattle has been rising at a significant rate, the cause of which is not well understood. There have been multiple reasons hypothesized to explain this but the most influential one has been found to be double ovulation due to lowered levels of progesterone. Metabolism by the liver leading to decreased progesterone levels at time of ovulation leads to an increase in circulating luteinizing hormone, and therefore the occurrence of codominance and increased likelihood of a double ovulation event occurring. Twining has many negative health risks associated with it and there are three current methods that aim to either maintain higher levels of progesterone during ovulation or function to eliminate one twin while still in its developmental stage. Better understanding of the main mechanism behind increased twining rates allows beneficial decisions to be made at various times throughout a cow’s normal reproductive cycle and may even influence factors such as feeding schedule or breeding protocol.