You are probably aware that hormones affect a woman's life in various ways. They carry information from one organ to the other, and they affect most body functions. There are not only ones that affect reproduction, but others are responsible for development for instance. But this article will only cover the ones that affect a woman's sex drive.
Let me begin with the one that controls menstrual cycle and her sexual organs. It is estrogen. It is responsible for lubrication of the vagina, a proper sleep pattern and even a stable mood. So, when any of those three are unstable, then the reason is likely to be an imbalance of the estrogen levels.
The next one is testosterone. That is right. It is not only produced in the male body, but they are also produced by the ovaries. They are responsible for sexual desire and the levels of estrogen. So, besides indirectly affecting what the estrogen does, if you notice the reduction of arousal then there is a problem with testosterone production in the ovaries.
Menstrual cycle and pregnancy are also affected by progesterone, but it is not yet clear how it affects a woman's sexual behavior. It probably changes their attitude toward sexuality – like if they are in the mood for something romantic or hardcore – but it is not yet proven.
While other hormones affect a woman's body, as well, these are the only ones that have a direct affect on a woman's libido, so if there are any problems with it, then their levels are likely to be responsible.