Neurobiology of trust

Corante's Brain Waves consistently offers interesting content. This post on the neurobiology of trust interested me because of an aside on pregnant women:
We also found that women in the experiment who are ovulating were significantly less likely to be trustworthy (for the same signal of trust). This effect is caused by the physiologic interactions between progesterone and oxytocin, and it makes sense behaviorally: women who are, or are about to be, pregnant, need to be much more selective in their interpretation of social signals, and also need more resources than at other times.
I'm at the age where seemingly half the women I know are pregnant at any point in time, so I'll know now not to take it personally when they treat me with unusual suspicion.