Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions.   Wa alaikum assalam wa rahmatullahi wa barakatuh.   As to what follows:   In response to your question, we say: If the woman cannot fast because of her pregnancy then she can make up for the fast after Ramadan because Allah the Exalted said, “but if any of you is ill or on a journey, the same number (should be made up) from other days”  [al-Baqarah: 184]. The pregnant woman takes the ruling of the sick person because of her need for food. The authors of the Sunan transmitted a hadith of the Prophet (peace be upon him) that he said, “Allah, the mighty and sublime, has waived fasting and half of the prayer for the traveler and for pregnant and breastfeeding women” [an-Nasai (2315)].  This means that she can take advantage of this concession and make up for the missed fasts later, if Allah wills. Is she required to feed the poor? No, she is not required to feed the poor, rather, her making up for the missed fasts suffices because the verse did not mention anything except making up for the missed fast. Allah the Exalted said, “but if any of you is ill or on a journey, the same number (should be made up) from other days”  [al-Baqarah: 184].  

Dr. Khalid al-Mosleh