Taking care of infants require specialized care, if this is your expertise then this cover letter is for you
Dear Mrs. Morrison,
Let me take care of your little one. I am a very gentle, loving and experienced caregiver. I am mindful of the needs of a newborn baby. I am very precise when it comes to feeding and nursing times. I am meticulous in handling medication, preparing milk formula or keeping tabs on dates of stored breast milk. I strictly follow household and newborn care rules you have in place; I am used to working shifts and long hours caring for an infant. I can also do light housework during the baby's nap times such as sterilizing milk bottles and keeping the nursery clean and organized. I am healthy, energetic and a non-smoker.
If you feel my skills suit your baby care needs, please give me a call at 555-8874. I look forward to hearing from you.