Pregnancy and Breastfeeding

A pregnant or breastfeeding woman who fears there would be a burden on herself if she fasted may break her fast, and she must pay it back, just like the sick.The Prophet ﷺ said:
“Allah Almighty has relieved the traveler of fasting and some parts of Salah (daily prayers), and He relieved the pregnant and the breastfeeding woman of fasting.”
[ Source: Bukhari.]
However, if she fears the burden on only her child or fetus, then she must pay the missed fasts back and feed one poor person for every missed day. Ibn ‘Abbas said:
“As for the pregnant and breastfeeding women, if they fear the burden of fasting on their children, then they must pay it back (the missed fasts) and feed one poor person for every missed day.”
[ Source: Abu Dawud.]
source: islamkingdom