Answered by Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him)
The hadith states that if someone prays the five prayers in congregation for forty days consistently catching the opening takbir with the imam they will be safe from the Fire and safe from hypocrisy. How can a woman attain this reward if her monthly cycle prevents her from praying for forty days consistently?
She can attain the reward by praying in congregation consistently up until her cycle starts. Then as soon as it finishes she continues where she left off.
 Narrated by al-Tirmidhi