Answered by Shaykh Amjad Rasheed
When does a pregnant woman stop praying?

In the Name of Allah, Most Merciful and Compassionate
May His blessings and peace be on His Beloved Prophet, the best of creation, and his family, companions, and followers
Pregnancy in itself is not among the reasons that permit delaying the prayer past its time.
However, if praying becomes very difficult to perform in its time, some of the imams have permitted joining prayers in that case, such as Imam al-Nawawi and Al-Khateeb al-Shirbini.
It is also permissible for a sick person who finds it difficult to perform the prayers in their times to join dhuhr and asr together, as well as maghrib and isha, in the first of the two prayer’s times [s. dhuhr or maghrib], or in the second [s. asr or isha], according to what is easier.
– Amjad.
(Translated by Shazia Ahmad)