Breastfeeding during pregnancy

Maui

Hi all I'm currently 6wks pregnant with baby #3 and I have a 5 month old that I still breastfeed at night mostly. Is it safe to still be breastfeeding? I would feel bad if I couldn't breastfeed my baby anymore because breastfeeding at night calms her down and helps her sleep. At the same time I'm worried about my little one inside my belly as well. Any advice ladies?