https://theedencenter.com/9th-month-mikveh/
Many women in Israel, regardless of their level of observance, come to the mikveh in their ninth month of pregnancy— a segula (practice) that is believed to make birth easier. This practice is especially common for women of Mizrachi/Sepharadi descent, but becoming more popular across the board.
This woman’s immersion evokes the idea of bringing tahara, purity and God’s presence, into the birth process. The living waters of the mikveh parallel the waters of the womb. By immersing, the woman unites the spiritual aspects of the mikveh waters, that symbolize being enwrapped by Torah and the Shekhina, with the physical nature of the womb and birthing process. Tevilla is therefore a very female way to bring Hashem into the process of preparing for labor.
Tevilla for a pregnant woman is a kabbalistic segula, not a halakha. Therefore, there are no specific rules about the procedure, and no special preparation is needed. There is no requirement to remove hatzitzot (physical barriers), though washing one’s body before entering makes it nicer for those coming after. Likewise, there is no bracha (blessing) to recite (as it is not a mitzvah).
Some women come to the mikveh as close as possible to the due date, others – as soon as they begin the 9th month, others – at any other convenient point. You can ask the balanit (mikveh attendant) to supervise, but she does not need to be in with you at the time of immersion, nor say “Kasher”. As this tevilla is a minhag (custom), there is also no specific required number of immersions.
Once a woman is in the waters, it’s an opportune time for personal prayers for the baby, the birth process, herself, parenting, others, or whatever is on her mind. Much has been said in Hassidic philosophy regarding the connection between the womb and the mikveh; from one we emerge into life, from the other we emerge pure and spiritually elevated – a new spiritual life. Thus it is an ideal time for davening (praying) from the heart, sharing fears with God, as well as concerns for one’s health, the health of the child and in general asking for help on the practical level regarding the birth.
For a woman who is immersing–try to transform it into a mindful experience, focus on what you are feeling in the present, and any feelings you have going into birth. Concentrate on your fears, concerns, hopes, desires. Allow your feelings to come to the surface, rather than hide from them. Feel the embrace of the mikveh waters, and realize that just as the waters surround you, so too are you surrounded by God’s presence. This is also what your baby is feeling. Connect to the warmth and flow of the waters and Hashem’s presence, the connection of living waters (מים חיים) with the waters that will bring forth life. Allow that feeling to fill you and carry it with you into the birth process, a moment between you and the Divine. God is there with you, in the mikveh and during birth, as you partner in creation.
The Sages taught in a baraita: One may go out with a preservation stone, which prevent miscarriages, on Shabbat. They said in the name of Rabbi Meir that one may go out even with the counterweight of a preservation stone; i.e., a stone or another object that was weighed against and found equivalent to the weight of the preservation stone, which is also effective. And this leniency applies not only to a woman who miscarried in the past and is concerned that she may miscarry again; rather, it applies even to a woman who never miscarried and is concerned lest she miscarry for the first time. And it applies not only to a woman who is aware that she is pregnant; rather, it applies even if a woman suspects that she may become pregnant and miscarry. Rav Yeimar bar Shelamya said in the name of Abaye: And this applies only when he happened upon an object that was found equal to the preservation stone when he weighed it against that stone, not when one alters the object to equal the weight of the preservation stone. Abaye raised a dilemma: With regard to a counterweight to the counterweight, i.e., one who finds an object and determines its weight by weighing it against the counterweight of the preservation stone, what is its legal status? May a woman go out into the public domain with it? The Gemara concludes: Let this dilemma stand unresolved.
(2) May the LORD answer you in time of trouble,
the name of Jacob’s God keep you safe. (3) May He send you help from the sanctuary,
and sustain you from Zion. (4) May He receive the tokens of all your meal offerings,
and approve your burnt offerings. Selah. (5) May He grant you your desire,
and fulfill your every plan. (6) May we shout for joy in your victory,
arrayed by standards in the name of our God.
May the LORD fulfill your every wish.
(7) Now I know that the LORD will give victory to His anointed,
will answer him from His heavenly sanctuary
with the mighty victories of His right arm. (8) They [call] on chariots, they [call] on horses,
but we call on the name of the LORD our God. (9) They collapse and lie fallen,
but we rally and gather strength. (10) O LORD, grant victory!
May the King answer us when we call.-c
May it be Your will, O great, mighty and awesome G-d, that the merits of this poor woman who is trembling and crying out in her pains of childbirth, be remembered before You. If she has done anything against Your will, forgive and cleanse it through her suffering in the pain of her labor. May the sound of her cry ascend to Your Throne of Glory, and seal the mouth of her accusers; but may those who defend her with good deeds be gathered before You as is Your custom, to bestow goodness on the worthy and non-worthy alike. Spread Your mercy upon her, for You answer in time of distress. O merciful Ruler who is merciful to all, who redeems and saves, hears and answers!
(Sefer Yad L'Yodelet)
ברכת שהחיינו
בָּרוּךְ אַתָּה יְהֹוָה אֱלֹהֵינוּ מֶלֶךְ הָעוֹלָם שֶׁהֶחֱיָנוּ וְקִיְּמָנוּ וְהִגִּיעָנוּ לַזְמַן הַזֶּה:
Customary Blessing - after the birth of a girl
בָּרוּךְ אַתָּה ה' אֱלֹהֵינוּ מֶלֶךְ הָעוֹלָם הַטּוֹב וְהַמֵּיטִיב.
Customary Blessing - after the birth of a boy
(א) ארבעה צריכים להודות יורדי הים כשעלו ממנה והולכי מדברות כשיגיעו ליישוב ומי שהיה חולה ונתרפא ומי שהיה חבוש בבית האסורים ויצא. ואומרה על הס"ת לאחר ברכה אחרונה. אם איחר יש לו תשלומין לברך כל זמן שירצה ונכון שלא לאחר שלשה ימים (שו"ע או"ח ריט).
(ב) בָּרוּךְ אַתָּה יְהֹוָה אֱלֺהֵֽינוּ מֶֽלֶךְ הָעוֹלָם הַגּוֹמֵל לְחַיָּבִים טוֹבוֹת שֶׁגְּ֒מָלַֽנִי כָּל טוֹב:
(ג) והקהל עונים: מִי שֶׁגְּ֒מָלְ֒ךָ טוֹב הוּא יִגְמָלְ֒ךָ כָּל־טוֹב סֶֽלָה:
(1) Rav says, (Maseches Berachos 54) that four are obligated to offer thanks: persons who have safely completed a sea or land journey, or who have recovered from a serious illness, or have been released from captivity. One who is obligated to recite the blessing of thanksgiving should do so at the Torah-scroll after the blessing that follows the Torah reading. It is proper not to delay the recital of the blessing for more than three days.
(2) Blessed are You, Adonoy our God, King of the Universe, Who bestows goodness upon the guilty, Who has bestowed every goodness upon me.
(3) The congregation responds: He Who has bestowed goodness upon you, may He bestow every goodness upon you, forever.
The above blessing is mandatory after giving birth and should be recited in the presence of 10 Jews.
Ideas for how and where to say it:
1. At shul during Torah reading (needs to be arranged with the Gabbai)
2. In the context of a name-giving ceremony, with at least 10 others present
3. Within a more creative context (e.g. gathering friends/family together for a more personally developed ritual, reciting the blessing, and have people recite the response)
(א) דיני יולדת ומפלת. ובו י"ד סעיפים:
יולדת אפילו לא ראתה דם טמאה כנדה בין ילדה חי בין ילדה מת ואפילו נפל וכמה הם ימי טומאתה עכשיו בזמן הזה כל היולדות חשובות יולדות בזוב וצריכות לספור שבעה נקיים נמצאת אומר שיולדת זכר יושבת ז' ללידה וז' לנקיים לזיבה והיולדת נקבה יושבת שבועים ללידה וז' נקיים לזיבה ימי לידה שהם ז' לזכר וי"ד לנקבה אם לא ראתה בהן עולים לספירת זיבתה ואם שלמו ז' נקיים בתוך י"ד לנקבה הרי זו אסורה עד ליל ט"ו ואם טבלה קודם לכן לא עלתה לה טבילה: הגה ולאחר ז' לזכר וי"ד לנקבה מותרת לבעלה מיד מאחר שספרה ז' נקיים ולא חזרה וראתה.
(1) A woman giving birth: even if she has not seen blood, is ritually impure as though she were a menstruating woman; whether she delivered a live child, or whether she delivered a stillborn child and even if she miscarried. And how many are the days of her ritual impurity? Now, in this time, all childbearers are considered as those delivering in a flow and require to count seven clean days; it follows to say that one who delivers a male sits seven for the birth and seven clean (day)s for the blood-flow, and one who delivers a female sits two weeks for the birth and seven clean (day)s for the blood flow. The days of birth, which are 7 for a male and 14 for a female, if she did not see (any blood) on them, they count for the accounting of her blood-flow; and if seven clean days are completed within the 14 for a female child, such a woman is forbidden [from going to the mikvah] until the night of the 15th (day); and if she had immersed prior to that, the immersion does not count for her.
Rema: And after 7 for a male and 14 for a female, she is permitted to go to the mikvah, on account of the fact that she had counted seven clean (day)s and she did not further see (blood-flow).
Mishmeret Hatahara v. 2 (Rabbi Moshe Mordechai Karp) p. 157 writes that a woman shouldn’t go to the mikveh after she gave birth before she is healthy enough to go, which the doctors usually say is 5 or 6 weeks.
ברוך אתה ה‘ א-לוקינו מלך העולם אשר קדשנו במצוותיו וצוונו על הטבילה
The immersion after birth is l'shem mitzvah and a bracha is said.