Progesterone creams have been popularized by several books, and they are pushed by some pharmacies because they are simple, cheap to make, and they bring huge profit margins.
For ovulating women, I've seen this phenomenon interfere with the cycle. This overdosing also can lead to depression since it displaces normal neurotransmitters (happy hormones) off their receptor sites in the brain, causing a type of dependency. In fact, I've had to detoxify several women who had experienced severe fatigue and depression when trying to stop progesterone cream. No studies have demonstrated steady absorption of this form into the proper tissues.
On the other hand, sublingual forms of progesterone have been studied and proven to absorb very predictably and thoroughly. These forms are cheaper than creams, too.
Bottom line: Progesterone creams are an erratic source of progesterone and can cause further problems. Sublingual forms are best.