אורח חיים פ״חOrach Chayim 88

Se’if 1א׳

כָּל הַטְּמֵאִים קוֹרִין בַּתּוֹרָה וְקוֹרִין קְרִיאַת שְׁמַע וּמִתְפַּלְּלִין, חוּץ מִבַּעַל קֶרִי שֶׁהוֹצִיאוֹ עֶזְרָא מִכְּלַל הַטְּמֵאִים, וַאֲסָרוֹ בֵּין בְּדִבְרֵי תּוֹרָה בֵּין בִּקְרִיאַת שְׁמַע וּבִתְפִלָּה עַד שֶׁיִּטְבֹּל, כְּדֵי שֶׁלֹּא יִהְיוּ תַּלְמִידֵי חֲכָמִים מְצוּיִין אֵצֶל נְשׁוֹתֵיהֶן כְּתַרְנְגוֹלִין. וְאַחַר כָּךְ בִּטְּלוּ אוֹתָהּ תַּקָּנָה, וְהֶעֱמִידוּ הַדָּבָר עַל הַדִּין, שֶׁאַף בַּעַל קֶרִי מֻתָּר בְּדִבְרֵי תּוֹרָה וּבִקְרִיאַת שְׁמַע וּבִתְפִלָּה בְּלֹא טְבִילָה וּבְלֹא רְחִיצָה דְּתִשְׁעָה קַבִּין, וְכֵן פָּשַׁט הַמִּנְהָג: הַגָּה: יֵשׁ שֶׁכָּתְבוּ שֶׁאֵין לְאִשָּׁה נִדָּה בִּימֵי רְאִיָּתָהּ לִכָּנֵס לְבֵית הַכְּנֶסֶת אוֹ לְהִתְפַּלֵּל אוֹ לְהַזְכִּיר הַשֵּׁם אוֹ לִגֹּעַ בְּסֵפֶר (הַגָּהוֹת מַיְמוֹנִי פֶּרֶק ד') וְיֵשׁ אוֹמְרִים שֶׁמֻּתֶּרֶת בַּכֹּל, וְכֵן עִקָּר (רַשִׁ"י הִלְכוֹת נִדָּה) אֲבָל הַמִּנְהָג בִּמְדִינוֹת אֵלּוּ כַּסְּבָרָא הָרִאשׁוֹנָה. וּבִימֵי לִבּוּן נָהֲגוּ הֶתֵּר, וַאֲפִלּוּ בְּמָקוֹם שֶׁנָּהֲגוּ לְהַחְמִיר, בְּיָמִים נוֹרָאִים וּכְהַאי גַּוְנָא שֶׁרַבִּים מִתְאַסְּפִים לֵילֵךְ לְבֵית הַכְּנֶסֶת, מֻתָּרִין לֵילֵךְ לְבֵית הַכְּנֶסֶת כִּשְׁאָר נָשִׁים, כִּי הוּא לָהֶן עִצָּבוֹן גָּדוֹל, שֶׁהַכֹּל מִתְאַסְּפִין וְהֵן יַעַמְדוּ חוּץ (פִּסְקֵי מַהֲרִי"א סי' קל"ב):

One Who Has Had a Seminal Emission is Permitted In the Recitation of the Sh'ma, containing 1 s'if All those who are ritually impure may read from the Torah, recite the Sh'ma, and pray [the Amidah] - except for the baal keri (one who has an emission) who was excluded by Ezra from the rest of the ritually impure, and he [Ezra] prohibited him (the baal keri) from words of the Torah, the Recitation of the Sh'ma, or prayer [i.e. the Amidah] until he immersed, so that scholars would not be found to be [frequently intimate] with their wives like roosters. And afterwards they annulled that enactment, and they stood the matter on it's [original] law, that even the baal keri is permitted with regard to words of Torah, the Recitation of the Sh'ma, and prayer [i.e the Amidah] without immersion and without washing with nine kabs [of water], and such is the widespread custom. Rem"a: There are those who wrote that a menstruant woman in the days when she sees [blood] may not enter the synagogue or pray [the Amidah], or mention the Name, or touch the [Torah] scroll (Hagahot Maimoni ch. 4). And there are those who say that she is permitted in all [of those], and that is the correct opinion (Rashi, Laws of Niddah). But the practice in these lands [Ashkenaz] is according to the first opinion. And in the "clean days" [after menstruation, but before immersion] it is permitted [to do these things]. And even in a place where they are stringent during the High Holidays and similar days, where many assemble to go the synagogue, they are permitted to go to the synagogue like the rest of the women, for it would cause great sadness for them, that all are assembled and they stand outside (Terumat HaDeshen, Part II 132).