Shalom Rabbis At what point in pregnancy does a miscarriage cause the next child to not be considered a Bechor? Is it any miscarriage as even a very early miscarriage would be considered an opening of the womb or is there a point where before that it is not considered an opening since the fortis is not formed? Thank you

Shalom, Thank you for your question. The laws of what is considered as a birth which would exempt a following child from the obligation to have a pidyon haben, is quite techinical. In general a miscarriage of a fetus less than 40 days old would not be considered as a birth, and the following child would need a pidyon. A fetus that was miscarried after 40 days would exempt the following children from the law of a pidyon. However, if the fetus was more than 40 days old, but less than 3 months into the pregnancy, and no one checked to see if it had formed limbs, then a following son would have a pidyon with no blessing. I attach here a very good summary and sources of this law from the dinonline.org website. The Mishnah (Bechoros 8a) writes that a firstborn that is born after a miscarriage is considered to be a firstborn with regard to inheritance, but not with regard to pidyon ha-ben. The Mishnah explains that this refers to a miscarriage after forty days of pregnancy; if the fetus is less than forty days old, the child born after the miscarriage has the full status of a firstborn. This principle is ruled by the Shulchan Aruch (Yoreh De’ah 305:23). If there is a doubt as to the precise age of the fetus at the time of the miscarriage, the firstborn child is exempt from pidyon ha-ben, out of doubt (Shulchan Aruch 305:13). However, the Rema (23) adds that if the limbs of the fetus are yet unformed, the firstborn child that follows him is obligated in pidyon ha-ben (based on Maharik 143). The simple understanding of thie ruling does not refer to a case where the miscarried fetus was not checked, but to a case where it was checked, and no limbs could be discerned (see Chacham Tzvi 104, who explains that where the fetus was not checked, we assume that it’s limbs were regularly formed). However, the Pischei Teshuvah (39) cites several authorities who understand, based on the Maharik, that where the fetus was not checked, we assume that the following firstborn is obligated in pidyon ha-ben (the fetus is assumed to not have developed limbs; this is because of an assumption (chazakah) that the womb has not yet “become exempt” from pidyon ha-ben). See especially Noda Biyhuda, Tinyana, Yoreh De’ah 188, who writes that until the end of the first trimester (first three months), the fetus cannot be assumed to have formed limbs, and the following firstborn is obligated in pidyon ha-ben. See also Shivas Tzion (46). Therefore, one can conclude as follows: 1) If forty days have not passed since conception, the fetus does not exempt the subsequent firstborn from pidyon ha-ben. 2) If forty days have passed, but the first trimester (meaning the first three months of the pregnancy) was not reached, the pidyon ha-ben must be performed out of doubt, but no berachah should be recited. 3) If the miscarriage was after three months of pregnancy, no pidyon ha-ben is performed for the subsequent firstborn. Blessings.