Parents of infants are bombarded with safety recommendations, from cribs to car seats to the bottles they use—information parents seem to take to heart. Yet, surprisingly, close to half of parents are not heeding the advice of experts when it comes to feeding their babies.

A new study from the U.S. Centers for Disease Control and Prevention (CDC) reveals about 40 percent of parents are not following specific guidelines for introducing their infants to solid foods. According to child development experts, children are not ready to eat solid foods, like baby cereal, until 4 months old. A number of chronic health issues are also connected to early solid food consumption. Parents, therefore, are advised to wait to start their children on solid foods until they are 4 to 6 months old.

Formula-fed infants were twice as likely to be started on solids early than breast-fed babies, with 53 percent of formula-fed babies starting solids before age 4 months versus only 24 percent of breast-fed babies.

Why are so many parents seemingly throwing caution to the wind? Some study participants cited advice from their doctors, while others said they wanted their babies to sleep longer at night, their baby seemed hungry or seemed to want food they were eating themselves, or parents simply wanted to feed their babies something besides formula or breast milk.

When is a baby ready for solid food? Sometime after 4 months old when they can sit up by themselves and have lost the “tongue thrust” reflex, when a baby will push food out of their mouths with their tongue.