Also as your nipples get stimulated while your baby is breastfeeding this triggers the release of more prolactin hormone which has a rather negative effect on the reproductive hormones. (themamaneeds.com)
In addition, the pituitary starts to make more prolactin and less TSH. (ergo-log.com)
Crying women are often called «emotional» or (even worse) «hormonal» — though it's technically true; women have six times more prolactin, a hormone related to crying, than men — making their tears seem dismissible. (canadianbusiness.com)