Children are considered the national treasure of Mexico, and Mexicans will warmly welcome and cater to your children. Many parents were reluctant to bring young children into Mexico in the past, primarily due to health concerns, but I can't think of a better place to introduce children to the exciting adventure of exploring a different culture. One of the best destinations for kids is Cancún. Hotels can often arrange for a babysitter.
Before leaving, ask your doctor which medications to take along. Disposable diapers cost about the same in Mexico but are of poorer quality. You can get Huggies Supreme and Pampers identical to the ones sold in the United States, but at a higher price. Many stores sell Gerber's baby foods. Dry cereals, powdered formulas, baby bottles, and purified water are easily available in midsize and large cities or resorts.
Only the largest and most luxurious hotels provide cribs. However, rollaway beds are often available. Child seats or high chairs at restaurants are common. Consider bringing your own car seat; they are not readily available for rent in Mexico.