Hindi automatic, mama, kailangan mo talaga mag-file ng application sa SSS mismo para ma-add ang baby as dependent, usually within a certain period after birth para ma-qualify pa. A few of us did this right after we got home from the hospital kasi ayaw naming mawalan ng deadline, and honestly it's pretty straightforward, just bring the baby's birth certificate, your SSS ID, and filled-out form sa nearest SSS branch or you can ask kung pwede online na ngayon. Better to do it early talaga para covered na agad ang baby sa benefits!