The permissibility of carrying children during prayer, and their garments are regarded as being pure until it is realized that they are impure. Few actions will not invalidate the prayer, and the same applies if several such actions are done but are done separately
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ بْنِ قَعْنَبٍ، وَقُتَيْبَةُ بْنُ سَعِيدٍ، قَالاَ حَدَّثَنَا مَالِكٌ، عَنْ عَامِرِ بْنِ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ، ح وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قُلْتُ لِمَالِكٍ حَدَّثَكَ عَامِرُ بْنُ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ، عَنْ عَمْرِو بْنِ سُلَيْمٍ الزُّرَقِيِّ، عَنْ أَبِي قَتَادَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يُصَلِّي وَهُوَ حَامِلٌ أُمَامَةَ بِنْتَ زَيْنَبَ بِنْتِ رَسُولِ اللَّهِ صلى الله عليه وسلم وَلأَبِي الْعَاصِ بْنِ الرَّبِيعِ فَإِذَا قَامَ حَمَلَهَا وَإِذَا سَجَدَ وَضَعَهَا قَالَ يَحْيَى قَالَ مَالِكٌ نَعَمْ .
Abu Qatadi reported: I saw the Messenger of Allah (ﷺ) saying the prayer while he was carrying Umama, daughter of Zainab, daughter of the Messenger of Allah (ﷺ). and Abu'l-'As b. al-Rabi'. When he stood up, he took her up and when he prostrated he put her down, Yahya said: Malik replied in the affirmative.