Read and reflect on verse 5221 from Surah At-Talaaq: Now as for such of your women as are beyond, the age of monthly courses, as well as for such as do not have any courses, their waiting-period - if you...
وَاللَّائِي يَئِسْنَ مِنَ الْمَحِيضِ مِنْ نِسَائِكُمْ إِنِ ارْتَبْتُمْ فَعِدَّتُهُنَّ ثَلَاثَةُ أَشْهُرٍ وَاللَّائِي لَمْ يَحِضْنَ ۚ وَأُولَاتُ الْأَحْمَالِ أَجَلُهُنَّ أَنْ يَضَعْنَ حَمْلَهُنَّ ۚ وَمَنْ يَتَّقِ اللَّهَ يَجْعَلْ لَهُ مِنْ أَمْرِهِ يُسْرًا
Now as for such of your women as are beyond, the age of monthly courses, as well as for such as do not have any courses, their waiting-period - if you have any doubt [about it] - shall be three [calendar] months; and as for those who are with child, the end of their waiting-term shall come when they deliver their burden. And for everyone who is conscious of God, He makes it easy to obey His commandment: