How to Wash Your Baby, c. 1320

Getty MS 1, f. 29v (c. 1360-70)

"You should wash the baby after he has had a long nap. In warm weather, use tepid water. In cold weather, use warmer water, but never use scalding water. You should wash the baby two or three times a day, but take care not to wash him so long that he becomes red and overheated. When you wash his ears, make sure that the water doesn't get inside him. And if he, on his own, wants to kick his legs in the water, let him do it, because that builds his strength. If it is winter, wash the baby near the fire. Stretch out his legs and feet toward the kidneys. Bend his joints, and grease them with oil. You should also grease his nostrils with oil. Then dry him off with soft cloths, and if he is cold, warm him up first."

Francesco da Barberino, Reggimento e costumi di donna 

It's important to keep a rigorous baby maintenance schedule: two or three baths a day at the least, and remember to grease the joints so they don't squeak.