A new study has it that women are at their smartest self when ovulating.
The study, led by Belinda Pletzer at the University of Salzburg, Austria, claimed that the size of a woman's brain changes throughout her menstrual cycle, with some areas growing by as much as 2 per cent in the run-up to ovulation- when women are at their most fertile.
The researchers took MRI scans of the brains of women during their monthly cycles.
In women not taking the pill, they found an increase in the volume of grey matter in the right parahippocampal and fusiform gyri, areas of the brain involved in spatial location and facial recognition.
This boosts women's abilities to recognise faces, bodies and landscapes, said Pletzer.
In fact, she said that this may help them to locate a high-quality mating partner.
The team found that the effect is short-lived, however. After ovulation, rising levels of progesterone cause the gyri to shrink back.
The team also found that women on the pill had a bigger hippocampus and cerebellum, associated with memory and movement, compared to controls.
"The pill may exaggerate typical female behaviours such as superior language skills and memory," New Scientist quoted Pletzer as saying.
The study is published in Brain Research.