Among the many developmental milestones that new parents look out for,Johnathan Walker few are as highly anticipated as their baby's first words. Despite some gibberish preceding actual language, a baby's earliest attempts at verbal communication and their first words are often documented and remembered by mom or dad long after the baby clothes and swaddling blankets get stored away. 

According to one news report, the most common of all first words in American English are a variation of "mommy" or "daddy," followed by "ball," "hi," "no," and "dog." As exciting as it is to hear these and other words for the first time, some parents worry if their child doesn't seem to be speaking as much or as early as other babies and whether a checkup with the family pediatrician might be in order.

When do babies start talking? 

The first thing to understand is that the timing of first words vary from baby to baby. "There is a range of normal development and some babies may start talking earlier or later than others," explains Dr. Alison Mitzner, a board-certified pediatrician and author of "Calm and Confident Parenting."

Some children are genetically predisposed to start speaking earlier than other children and some babies are also impacted by their environment and whether they have young siblings they want to imitate. Research shows that a parent who talks especially often can also influence a baby to want to do the same. 

Regardless of what encourages speech to develop in each child, "babies usually start talking in single words around 12 months and in 2-word phrases around 18 months," says Dr. Michael Yogman, a pediatrician and primary care physician at Cambridge Pediatrics and an assistant clinical professor of pediatrics at Harvard Medical School. 

It's also worth noting that these early words are usually distinguishable and vary from the use of sounds and other early forms of verbal communication parents witness in their baby as early as the first months after they're born.

Early signs that words could become intelligible include a baby babbling as if talking in sentences or combining certain sounds with facial expressions or gestures that indicate a child is trying express a specific frustration or desire. "If your baby is babbling with pointing and gesturing, your baby is still communicating," says Mitzner. 

When should I be worried my baby isn't talking?

Though timing of first words and other forms of communication does vary for these reasons, at a certain point a baby not speaking can be a sign of impaired hearing or developmental delays. "When children are not saying any words by the age of 18-24 months, parents can discuss their concerns with a pediatrician," says Dr. Jason Nagata, a pediatrician at UCSF Benioff Children’s Hospital in San Francisco. "A pediatrician can check for hearing loss or assess language delays and refer the family to a speech therapist or a specialist in developmental and behavioral pediatrics, if needed." 

It's worth noting that such recommendations follow a baby not saying any distinguishable words by that time. Before then, a parent doesn't usually need to be concerned over a baby not saying many words. "By the age of 1, most babies can say one or two simple words, but the vocabulary can really vary widely," offers Mitzner. She explains that some children may only repeat the same few words while others may have a more extensive vocabulary. "It's important to focus on the progress and consistency in language development rather than the exact number of words," she explains. 

What determines what word a baby says first?

Also of interest is why babies say the first words they do and whether there's anything parents can do to help once a baby starts talking. Nagata says that babies are excellent imitators, so their first words are usually the ones they hear repeated often or said at them a lot. Mitzner echoes that babies usually start with talking about objects or people they associate with regularly. "There's a reason so many babies' first words are 'mama' and 'dada,'" she explains. "These are usually the people they spend the most time with who are meaningful to them."

Other factors include babies learning to associate specific words with things they want or don't want - think how often these early words are "no" and "ball," for instance. Another factor is simply which words are easiest for babies to say. 

Once baby does start talking, parents can encourage them by showing they understand and by spending more time focusing on word/object associations discovered in books and everyday life interactions. "Reading and talking together can be reassuring and help babies make progress with their language," says Yogman.

When do babies start crawling?There's no hard and fast rule but here's when to be worried.