Meowing kittens- enough milk?

My beautiful cat had four kittens today. They are all suckling on her nipples but I have no idea if milk is coming out. Would they keep sucking if no milk was coming out? They also seem to meow quite a lot. What should I do? I have read online that newborn kittens meowing alot is not normal. Please help me!

This is why you need to weigh each of them each day at about the same time.  It can look rough at the milk bar but so long as they are gaining weight there is nothing to worry about.

You need a set of electronic kitchen ditigal scales that weigh in grams as firstly that avoids having to struggle with decimal points, and secondly 10g is a nice easy number to remember, and it's the amount the kittens should each put on most days.

Record the results - I use an Excel spreadsheet - and it's easy to see if they are gaining or not.