It depends on what area of OB/GYN you are in. If you are in Mother/Baby, you will take care of moms and their babies, usually in a rooming-in situation (meaning baby stays with mom at all times, and never leaves her side). You need to do assessments on both mom and baby, help mom with breast or bottle-feeding, do lots of teaching.
If you are in a straight postpartum unit, then you look after mom, and baby is in the nursery, except for feeds. You do assessments on mom, and help with breastfeeding a bit, but not as much as in Mother/Baby.
If you are in Labor and Delivery, you help the moms duirng their labor and delivery of their babies and if they have c-sections, you scrub in in the OR.
If you are in an OBGYN office, you do assessments, check the pee of pregnant ladies for protein and bacteria, get stuff ready for pap smears and do health teaching.
Hope that helps!