"That is not menstruation, rather it is a kick in the womb, so let her work out the length of the menses that she used to have, and stop praying (for that period of time), then after that let her perform Ghusl for every for every prayer."
شَأْنُهَا لِرَسُولِ اللَّهِ ﷺ قَالَ لَيْسَتْ بِالْحِيضَةِ وَلَكِنَّهَا رَكْضَةٌ مِنَ الرَّحِمِ لِتَنْظُرْ قَدْرَ قُرْئِهَا الَّتِي كَانَتْ تَحِيضُ لَهَا فَلْتَتْرُكِ الصَّلاَةَ ثُمَّ تَنْظُرْ مَا بَعْدَ ذَلِكَ فَلْتَغْتَسِلْ عِنْدَ كُلِّ صَلاَةٍ