Hi,

I don't have a 18 months old or a 16 months old but from experience (as an occupational therapist), boys generally develop language later than girls and it is not uncommon for boys to not "talk" until they reach their 2nd birthday or a bit latter.

What is important to look for is how engaging your baby is during interaction with you and other children. Do they pay attention through making eye contact, do they understand what you are telling them either by responding through body language or words. Can they read your emotional status such as when you say "no" or when you indicate you are not happy.

Got to run so will write more later.

Hope that helps.