You puked a lot last night.
You vomited a lot last night.
Which verb is more suitable for stating that a baby vomited milk?
I would not say either about a baby.
I would say:
Our baby spits up milk.
Our baby was spitting up milk last night. (AmE)
Puke is a crude word for vomit, so I don't think you would want to use that for an innocent baby.
A baby that does not have an illness probably is not vomiting, but has colic or gas instead.
Neither verb is the correct past tense. The sentences should be You puked(vomited) a lot last night.
There are many other choices. http://www.thesaurus.com/browse/vomit
To Spit Up or Regurgitate are more appropriate synonyms.
In British English neither, use 'posset' instead because
VERB (possets, possetting, possetted)
(Of a baby) regurgitate curdled milk
"bless its little heart, it’s possetting again"
"From time to time the baby belched and possetted back a small quantity of milk."
"Of course, Freddie pulled my hair and possetted onto it as soon as I got home again!"
NB "To be sick" or to "sick up" is also used as a more polite synonym for 'puke' or 'vomit' in British English.
'Regurgitation' is also sometimes used about babies e.g. Some babies bring up more milk than others during or just after a feed. This is sometimes called ‘possetting’ or ‘regurgitation’ or ‘reflux’. http://www.nhs.uk/conditions/pregnancy-and-baby/pages/bottle-feeding-advice.aspx
So say: "The baby was possetting a lot last night".
("The baby possetted a lot last night" would also be ok, "was possetting a lot last night" is better if it happened over a longish period of time).
" Throws up" is better than "pukes" when referring a baby bringing out milk when unwell.
All the world's a stage, And all the men and women merely players. They have their exits and their entrances, And one man in his time plays many parts, His acts being seven ages. At first the infant, Mewling and puking in the nurse's arms.
I couldn't resist.