The human body is peculiar to say the least, but this latest discovery is slightly mind-boggling.
According to researchers from researchers from Cold Spring Harbor Laboratory a woman's breasts can technically "remember" the experience of being pregnant, and this "memory" helps them to produce more milk for their second (or third, or fourth) child.
Your breasts' incredible ability to recall is due to marks that are induced on the DNA of breast cells during pregnancy.
These cells become more receptive to pregnancy-related hormones, so when they are detected the second time round, glands produce milk quicker.
These marks (known as epigenetic marks) remain throughout your whole reproductive lifetime, according to the researchers.
An assistant professor at Cold Spring Harbor Laboratory (CSHL), Camila dos Santos, said: "It's as if the gland already knows those hormones."
Releasing the hormones oestrogen and progesterone during pregnancy triggers these changes in the breast, which prompts the mammary gland to produce milk.
Researchers used stem sells from mouse mammary glands to do the study. The mice who had previously been pregnant had marks that were "substantially different" from the mice that had never been pregnant.
They gave the mice who had been pregnant before the hormones to stimulate another real pregnancy, and they responded more rapidly than the other group of mice.