The custom of not leaving home and going to Shul after birth:[1]

A. The original custom:

It is an age old Jewish custom for women who are after birth to not leave their home for a period of four weeks from the birth[2], and to then enter a Shul [as their first destination prior to going anywhere else[3]].[4] They visit the shul even if they are still a Nidah.[5] The husband of the woman would receive an Aliyah to the Torah on this occasion[6], and the woman would answer to Kaddish, Barchu, and Kedusha, and recite the blessing of Hagomel[7] [for those accustomed to do so].

The reasons: There are several reasons behind the various parts of this custom: 1) A woman after birth is weak, and hence she would remain at home and rest for the first four weeks.[8] 2) A woman after birth requires Shemira, similar to a Chasan[9], and hence they would avoid leaving their house for a full month after birth, until the Shemira period expires. Going to a Shul as the first destination would help alleviate the need for Shemira from that time and on.[10] 3) She is required to recite Hagomel, giving thanks to Hashem for surviving her birth experience.[11] Hence, her first destination after birth is to a Shul for her to recite Kaddish and Kedusha and recite Hagomel to give thanks to G-d.[12] 4) A woman who gave birth needs to bring a Karban. Today, during exile, the above practice was instituted in the place of the Karban, through her husband receiving an Aliyah to the Torah upon her return to the outside.[13] 5) In order for a woman to begin her new phase with a matter of holiness, she goes first to a Shul to participate in a matter of Kedusha, such as answering Barchu, Amein Yihei Shmei Raba and the like.[14]

B. The custom today:

Practically, the widespread custom today is to no longer be particular in the above, and women leave their homes as close to a week after birth[15], and are not particular to first go to a Shul, recite Hagomel, and have their husbands receive an Aliyah.[16] Nevertheless, some sects of Jewry are particular in this even today.[17] Others arrange for a Minyan to take place in the house of the Yoledes, which then allows her to leave the home without restriction.[18]

The Chabad custom:[19] There exists a tradition from the Rabbeim to be particular in the above original custom, and for a woman to make a Shul her first destination after birth, prior to leaving to anywhere else, in order to begin her new after birth phase with a matter of holiness.

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[1] See Admur 88:2; Beis Yosef 88; Elya Raba 219:5; P”M 219 M”Z 3; Shaareiy Efraim 4:28; Birchas Habayis 27:17; Hisorerus Teshuvah 1:59; Aruch Hashulchan 219:6; M”B 219:3; Har Tzevi 1:163; Minchas Yitzchak 4:12; Divrei Yatziv E.H. 35; Betzel Hachochmah 6:78; Kinyan torah 4:22; Teshuvos Vehanhagos 1:195; Orchos Rabbeinu 1:91; Beir Moshe 8:120; Piskeiy Teshuvos 136:8; 219:10 regarding Hagomel; 239:11 regarding Shemira; Nitei Gavriel Nida Vol. 3 chapter 63:6 and 65; Shevach Habris 5:3

[2] See Admur 88:2 “If she herself has given birth in which she goes to the synagogue after four weeks, she may go even if she is a Nidah”; M”A 88:3; Shut Maharshal 58; Beis Yosef 88; Elya Raba 219:5; P”M 219 M”Z 3; Shaareiy Efraim 4:28; Birchas Habayis 27:17; Hisorerus Teshuvah 1:59; Aruch Hashulchan 219:6; M”B 219:3; Har Tzevi 1:163; Minchas Yitzchak 4:12; Divrei Yatziv E.H. 35; Betzel Hachochmah 6:78; Kinyan torah 4:22; Teshuvos Vehanhagos 1:195; Orchos Rabbeinu 1:91; Beir Moshe 8:120; Piskeiy Teshuvos 136:8; 219:10 regarding Hagomel; 239:11 regarding Shemira; Nitei Gavriel Nida Vol. 3 chapter 63:6 and 65; Shevach Habris 5:3

The reason: There are several reasons behind the various parts of this custom: 1) A woman after birth is weak, and hence she would remain at home and rest for the first four weeks. [Shut Maharshal 58; Shut Bach 46] 2) A woman after birth requires Shemira, similar to a Chasan, and hence they would avoid leaving their house for a full month after birth, until the Shemira period expires. [Nitei Gavriel ibid footnote 15] 

[3] See Rav Tiyah Viyal 108; Zichron Yehuda 46; Betzel Hachochmah 6:78; Pela Yoeitz 63:15; Nitei Gavriel 65:1 footnote 1; Piskeiy Teshuvos ibid

[4] Admur 88:2 “If she herself has given birth in which she goes to the synagogue after four weeks, she may go even if she is a Nidah”; M”A 88:3; Shut Maharshal 58; Beir Heiytiv E.H. 70:1; Noheig Katzon Yosef p. 141; Pleisi 194:2; Meishiv Nefesh p. 133; See also Admur Seder 13:3

[5] Admur ibid

[6] Shut Maharshal 58

[7] Seder Birchas Hanehnin 13:3; Igros Kodesh 20:102

[8] Shut Maharshal 58; Shut Bach 46

[9] See M”A 239:7; M”B 239:9; Brachos 54b; Sefer Shemiras Haguf Vihanefesh [Lerner] 180; Encyclopedia Hilchatit Refuit Leida p. 274

[10] Nitei Gavriel ibid footnote 15

[11] See Elya Raba 219:5 in name of Toras Chaim

[12] Betzel Hachochmah 6:78

[13] See M”A 282:18

[14] Rav Tiyah Viyal 108

[15] Nitei Gavriel ibid that in today’s times, on the contrary, doctors recommend a woman to leave the home after birth for the betterment of her mental health

[16] See Piskeiy Teshuvos 136:8; This is the widespread custom that I personally have witnessed, however see Nitei Gavriel ibid and Piskeiy Teshuvos 219:10 who write that women after birth are to first visit the Shul to answer Barchu and the like prior to doing anything else

[17] Nitei Gavriel 65:1

[18] Nitei Gavriel 65:3

[19] Rabbi Leibal Groner, brought in Nitei Gavriel ibid; Rav Tzevi Hirsh Chitrik testifies that he once asked the Rebbe after his wife gave birth as to where she should say the blessing and the Rebbe responded that it should be said immediately after the Mincha prayer and answer Kedusha, and so was done by the Rebbe’s own minyan.