A friend’s sister is expecting a baby boy and has put out feelers for potential nannies who can help her with the care of the newborn. She does not want a domestic helper who takes care of the child in addition to doing housework, but a dedicated carer whose job is to tend to the baby’s every physical need, except to suckle him from her own bosom. It may sound off-putting today, but before the invention of formula milk, in the 20th century, wet nurses were employed to breastfeed babies whose mothers were unable or unwilling to nurse their own child. Many Chinese still use the word nai ma (literally “milk mother”) to refer to modern-day nannies, an anachronistic job title that is patently incompatible with the job description. Given the nature of the work, it stands to reason that only the wealthy were able to afford wet nurses. In the households of the titled and privileged in China, it was common for infants to be breastfed by women who were not their biological mothers. The engagement of wet nurses for imperial princes and princesses was, as with all things royal, governed by strict protocol. The age, appearance and health of the candidates were criteria for selection, as were the viscosity and colour of their milk. Curiously, a wet nurse in the imperial household would suckle a prince if she had just given birth to a girl, and a princess if her own baby was a boy. During the Ming dynasty (1368-1644), for example, an “Office of the Breasts”, managed by the chief eunuch of the imperial household staff, was situated just outside the imperial palace, where 40 potential wet nurses were housed. Another 80 were on standby in their own homes. All candidates must be married, be between the ages of 15 and 20, and have “regular features”. Curiously, a wet nurse in the imperial household would suckle a prince if she had just given birth to a girl, and a princess if her own baby was a boy. Due to the intimate connection between wet nurses and their imperial charges, the latter, even in adulthood, might feel greater affection for them than they did their own biological mothers. When the young Shunzhi Emperor refused to listen to his ministers and his mother, the empress dowager, and insisted on personally leading the military campaign against a rebellion in 1659, his mother sent his former wet nurse to beg him not to go. Only then did the 21-year-old hothead relent and leave the fighting to his generals. As a reward for nursing and caring for them in infancy, emperors often confer titles on their former wet nurses. Shunzhi’s former wet nurse, who also went on to take care of his son, the future Kangxi Emperor, was made a lady of the realm in 1677 and buried with honours when she died four years later. It was recorded that Kangxi personally paid his respects at her grave four times during his reign. There were, however, imperial wet nurses who abused the favour conferred on them. Wang Sheng, the former wet nurse of Emperor An, of the Eastern Han dynasty, who reigned from AD106 to 125, conspired with palace eunuchs to slander imperial relatives and court officials before the emperor, resulting in mass executions and exile. Ke Yinyue, the former wet nurse of the Ming dynasty’s Tianqi Emperor (reigned 1620-1627), even lived as the wife of the chief eunuch, Wei Zhongxian. Together, the notorious couple plunged the imperial palace into ignominious depths of intrigue, corruption and depravity. Most wet nurses, however, are good women who ensured the survival of infants at a time when there were few available and viable alternatives to breast milk. It begs the question though: assuming that the wet nurses’ own babies survived childbirth or early infancy, how were they fed when their mothers were nursing other people’s children?