The Gemara tells the tragic story of the city of Biter, which served as the last stronghold during the Jews’ revolt against the Romans in the period following the destruction of the Second Temple. The Romans ultimately captured the city and killed all its Jewish inhabitants. According to some estimates, half a million Jews perished during the fall of Biter. The Gemara further relates that the Romans refused to allow the surviving Jews to bury their slain brethren, and the corpses remain strewn along the ground for seven years. The blood of these victims, the Gemara tells, formed rivers which flowed to the agricultural fields belonging to the gentiles in the surrounding areas, and served to fertilize the fields.
Finally, after seven years, the Roman authorities granted the Jews permission to bury the victims. When the Jews approached the corpses, they discovered that the bodies had miraculously remained intact, and did not decompose. To celebrate this miracle, the Sanhedrin, which at the time was stationed in the city of Yabneh, instituted the fourth Beracha of Birkat Hamazon, the Beracha of "Hatob Vehametib." The term "Hatob" gives praise to God for preserving the bodies, and "Vehametib" celebrates the fact that the bodies were finally able to be buried.
Additionally, the Sages of the time enacted that whenever something joyous happens to a person, and he shares the joyous event with somebody else, he should recite the Beracha, "Baruch Ata Hashem Elokenu Melech Ha’olam Hatob Vehametib." Accordingly, the Shulhan Aruch writes (Orah Haim 223) that when a baby boy is born, an event which brings joy to both parents, the parents should recite the Beracha of "Hatob Vehametib" at the birth.
However, despite this ruling of the Shulhan Aruch, the Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909) writes that the prevalent custom is not to recite this Beracha at the time of the child’s birth. Instead, when the father recites the Beracha of "Shehehiyanu" at the Berit Mila, he should have in mind for the Beracha to refer to the birth of the child, and not only to the Misva of Mila. The Ben Ish Hai cites this ruling in the name of the Hesed La’alafim (Rav Eliezer Papo, 1770-1828); this ruling is cited as well by the Kaf Ha’haim (Rav Yaakov Haim Sofer, Baghdad-Israel, 1870-1939).
As for the final Halacha, the Yalkut Yosef (vol. 3) observes that the common practice appears to follow the view of the Ben Ish Hai, that this Beracha is not recited at the birth. Hacham Bension Abba Shaul (Israel, 1923-1998), however, writes that one who wishes to adopt the custom of reciting the Beracha at the time of birth, in accordance with the ruling of the Shulhan Aruch, may certainly do so. Hacham Bension also writes that those who do not recite the Beracha at the time of birth should, preferably, have in mind during their next recitation of Birkat Hamazon that the fourth Beracha, "Hatob Vehametib," should fulfill the obligation to recite this Beracha after the birth.
By contrast, Rabbi Moshe Halevi (Israel, 1961-2001), in his work Birkat Hashem, rules that it is proper to recite "Hatob Vehametib" at the time of birth, as the Shulhan Aruch requires.
Practically speaking, it appears that the prevalent practice is not to recite this Beracha at the time of birth, and this would therefore seem to be the preferred practice, especially in light of Hacham Bension’s suggestion that one may fulfill this obligation through the recitation of Birkat Hamazon. Nevertheless, those who wish to recite this Beracha at the time of birth to give praise to God for this joyous occasion certainly may do so.
Summary: It is customary not to recite the Beracha of "Hatob Vehametib" upon the birth of a baby boy, and to instead rely upon the Beracha of "Shehehiyanu" recited at the Berit Mila. Nevertheless, those who wish to recite the Beracha at the birth have a basis on which to rely.
