Siman 73
Presented here for study, not as a practical ruling. The Shulchan Aruch rules by Sephardi custom, the Rema's glosses by Ashkenazi custom, and the Kitzur follows Ashkenazi custom. For a practical question, ask your rabbi.
א שְׁנַיִם שֶׁהָיוּ יְשֵׁנִים בְּטַלִּית אֶחָד, וּבְשַׂר שְׁנֵיהֶם נוֹגְעִים זֶה בָּזֶה, לֹא יִקְרְאוּ קְרִיאַת שְׁמַע, אֶלָּא אִם כֵּן הָיְתָה טַלִּית מַפְסֶקֶת בֵּינֵיהֶם מִמָּתְנֵיהֶם וּלְמַטָּה.
1 The One Who Sleeps Next To One's Spouse and One's Children and How to Conduct Oneself, Containing 4 S'ifim Two that were sleeping under one cloth, and the skin of the two of them is touching each other's - they may not recite the Sh'ma unless the cloth was separating between them from the waist downwards.
ב אִם הָיָה יָשֵׁן עִם אִשְׁתּוֹ, קוֹרֵא בַּחֲזָרַת פָּנִים לְצַד אַחֵר, וַאֲפִלּוּ בְּלֹא הַפְסָקַת טַלִּית, מִשּׁוּם דַּחֲשִׁיבָה כְּגוּפוֹ. וְיֵשׁ מִי שֶׁאוֹסֵר, וְנָכוֹן לָחוּשׁ לִדְבָרָיו.
2 If one was sleeping with his spouse, he may recite by turning away his face to the other side. And [this is so] even without the separation of a cloth because [one's spouse's body] is considered like one's [own] body. And there is [an authority] who forbids this, and it is correct to heed his words.
ג אִם הָיָה יָשֵׁן עִם בָּנָיו בְּעוֹדָם קְטַנִּים, מֻתָּר לִקְרוֹת בַּחֲזָרַת פָּנִים בְּלֹא הַפְסָקַת טַלִּית. וְאִם הֵם גְּדוֹלִים, צָרִיךְ לְהַפְסָקַת טַלִּית.
3 If one was sleeping next to one's children while they are still minors, it is permitted to recite through turning one's face without the separation of a cloth. And if they are older, one needs the separation of a cloth.
ד עַד כַּמָּה הֵם חֲשׁוּבִים קְטַנִּים, הַתִּינוֹק עַד שֶׁיִּהְיוּ לוֹ י"ב שָׁנִים, וְהַתִּינֹקֶת עַד שֶׁיִּהְיוּ לָהּ י" א שָׁנִים, וַאֲפִלּוּ הֵבִיאוּ ב' שְׂעָרוֹת, מֻתָּר. וּבִשְׁנַת י"ג לְתִינוֹק וְי"ב לְתִינֹקֶת אִם הֵבִיאוּ ב' שְׂעָרוֹת, אָסוּר בְּלֹא הֶפְסֵק. וְאִם לֹא הֵבִיאוּ ב' שְׂעָרוֹת מֻתָּר. וּמִשְּׁנַת י"ג וָאֵילָךְ לְתִינוֹק וְי"ב לְתִינֹקֶת, אֲפִלּוּ לֹא הֵבִיאוּ ב' שְׂעָרוֹת, אָסוּר:
4 Until what age are they considered minors? The male child, until he is 12 years old and the female child until she is 11 years old. And even if they produced 2 [pubic] hairs, it is permitted [up to that age]. And during the 13th year for a male child and the 12th year for a female child, if they have produced 2 hairs, it is forbidden without the separation [of a cloth]. And if they have not produced 2 hairs, it is permitted. And from the 13th year and on for a male child and the 12th for a female child, even if they have not produced 2 hairs, it is forbidden.