COCPs may increase natural vaginal lubrication. Other women experience reductions in libido while on the pill, or decreased lubrication. Some researchers question a causal link between COCP use and decreased libido; a 2007 study of 1700 women found COCP users experienced no change in sexual satisfaction. A 2005 laboratory study of genital arousal tested fourteen women before and after they began taking COCPs. The study found that women experienced a significantly wider range of arousal responses after beginning pill use; decreases and increases in measures of arousal were equally common.