For the same reason they use a soother (known as a dummy in the UK)
It soothes them.
Well a 9 month old baby may still need to suck his/her fingers. Babies suck on fingers and pacifiers for security. They somehow need it. If you want to get a baby to stop sucking his/her fingers, give him/her a pacifier to suck on instead. Or keep him/her occupied so whenever he/she sucks on her fingers, give him/her a toy to play with.
That is how babies eat.
TEN fingers
Pacifiers
Pacifiers
of course they do
Babies mostly do
Babies can begin sucking their thumbs as early as the womb, typically around 20 weeks of gestation. After birth, many infants instinctively suck their thumbs or fingers for comfort and to self-soothe, often starting within the first few weeks. Thumb sucking can provide a sense of security and is a natural behavior for many babies.
suck my babies
We both suck our thumbs when we are babies
it does suck, sims only have babies on pc,so that why i switched from ps2,
because of the peewie babies, u suck