Any woman who is divorced or widowed may not get married or engaged to another until she waits 90 days, excluding the day she was divorced or on which her husband died and the day on which she becomes engaged, so that it be known if she is pregnant or not pregnant, to distinguish between the seed of the former and the seed of the latter. Rem"a: But she is permitted to make a commitment for marriage without formal engagement (Beit Yosef in the name of a responsum of the Rosh and Terumat haDeshen 217) as long as he doesn't enter into a house with her. From the day of the writing of the divorce document one counts for a divorcee, even if it was [written] on condition [of going into effect later than the day on which it was written] or she didn't receive it until many years later -- from the day of the writing one counts, for he does not seclude himself with her after writing it for her. Rem"a: And some say that one counts from the day of the giving of the divorce document (Tur in the name of the Rosh) and in accordance with that it is appropriate to be stringent, thus it appears to me. And it is a decree of the Sages that even a woman who is unable to give birth, and even if she is divorced or widowed during the engagement period [when sexual relations with the future husband are forbidden], must wait 90 days. Even a minor or an elderly woman or an infertile woman or a woman who never underwent puberty, or even if her husband is abroad or a eunuch or ill or imprisoned, or [even] someone who miscarries after her husband's death, or even a virgin from the engagement period, [all these] must wait 90 days.
A woman waiting to marry her brother-in-law [after the death of her husband before having children with him] whose brother-in-law dies, must wait three months after the death of the brother-in-law.
If she was impregnated by Reuven, and both of them agree that from him she became pregnant, and she goes and gets engaged to Shimon, and he divorces her, and she wishes to marry Reuven, she must wait 90 days after divorcing Shimon.
Someone remarrying the woman he divorced need not wait.
A maidservant or a female convert who were married to husbands while they were non-Jews or servants and converted or were freed must wait. Even a convert and his wife who convert; [the court] separates them for 90 days in order to distinguish between seed implanted in holiness and seed implanted not in holiness.
A [young girl who] refuses [to marry the man her mother or brothers arranged for her to marry while she was a minor] need not wait [90 days after this refusal before marrying someone else]. They only decreed [the waiting period] for a divorcee. And likewise a [single] woman who has relations need not wait, because she turns herself during sex such that she will not become pregnant. And likewise a raped women or a seduced woman need not wait [90 days after the rape or seduction to marry another man]. And the same applies to a woman taken captive, even if she is an adult. Rem"a: Some say that all of these need to wait if they are adults and capable of becoming pregnant (Tur). A woman who is raped while married to her husband, if she had not had sex with her husband prior to the rape, she must wait (Or Zarua).
A concubine who is designated for one man, but wants to marry another, needs to wait [before marrying the other].
A woman who was married by mistake and it is known that she is forbidden to her husband, and the beis din sends her out from him [makes them divorce]: if she is a minor [under 12] and is not able to give birth, she does not need to wait [before marrying someone else], because this is not common and anything that is uncommon within a majority, they [the Rabbis] did not decree upon it.
A woman who is divorced and a rumor of invalidity against the divorce document goes out, and [the court] requires another divorce document because of the slander, some say she must wait three months from the second divorce document and some say that she need count only from the first divorce document. Rem"a: One should follow the first position (this is the opinion of the R"I and the Rosh, which the Tur wrote in their names). And likewise if she is divorced merely due to rumors that she had become engaged to someone, she must wait (Beit Yosef in the name of the Rashba).
Someone who engages [one of these women] within [the] 90 day [period] -- [the court] excommunicates him. Rem"a: And some say that he needs to divorce her], and if he is an Israelite [i.e., not a priest] he takes her back after 3 months, while a priest may not take her back (Tur). This applies specifically if he transgressed deliberately, but if he engaged her by accident, he need not divorce her, but [the court] separates them (Mahari"v 73) and some are strict even in the accidental case (Terumat haDeshen 216). And it appears that in the case of a priest who is forbidden to take her back, one should rely on the lenient opinion and not require divorce; but in the case of an Israelite [= non-priest], one should not rely on the lenient position regarding accidents, thus it appears to me. If he divorced her, she is forbidden to live with him in the same mavoi (Riva"sh 360). If the court did not compel him [to divorce her] until after 3 months had passed, even though he engaged her transgressively, they no longer compel him [to divorce her], since once they passed, they passed (Mordekhai ch. Haholetz in the name of the Mahara"m). And if he married [her] and divorced [her], see below in this section subsection 12 the law regarding the ketubah. If he engaged her and fled, we do not excommunicate him. Rem"a: And we advise him to flee (Tur in the name of Rabbenu Yehiel). There is one who says that this fleeing must be so far that his return would be after three months, but this does not appear to be the case based on the words of other decisors.
The Rabbis decreed that a man should not engage a woman who is pregnant from another, or who is nursing another ['s child], until the infant has twenty four months. Rem"a: which is [counted] in the way that they set the month--one full and one missing [i.e. 30 days and 29 days] (Hagot Mordechai Chapter HaCholetz) except for the day he was born and the day she was engaged. The intercalary month is part of the twenty four month count. Rem"a: And some say that ideally that one should take into account the intercalary month (Terumat HaDeshen Siman 216). whether she is a widow or a divorcee or engaged in sex while single. Rem"a: Some are lenient with one who had sex while single (Hagot Mordechai Chapter HaCholetz). And some are lenient with one who abandoned herself to promiscuity so that her husband can guard her (Responsa of Ri Mintz Siman 5). Even if she gave her child to a nurse, or if she weaned him within 24 months, she should not marry. Even if the nurse swore or vowed in public that she would not go back on [the deal]. Rem"a: And some say that if the nurse swore and she entered [into the engagement], she should not leave (Hagot Mordechai Ketubot). Even if she swore to a great man, like those who go in the courtyard of the king. But if her child died, she is permitted to marry and we don't suspect that she might kill her child [in order to marry]. So too if she weaned [the child] while her [previous] husband was still alive, or if she never gave milk at all. For example, if her breasts had shriveled. Or if her milk stopped while her [previous] husband was still alive. Or if she gave her child to a nurse three months before her [previous] husband died and she had not nursed at all within the three months. [In these cases] she is permitted to remarry.
If he transgressed and married a pregnant or breastfeeding woman within this time, we ostracize him, unless he fled. And he shall divorce the woman, even if he is a priest. He has to pay the ketubah (marriage contract) if she claims it from him. If he is an Israelite, he may remarry her after 24 months of breastfeeding, and he must write her another ketubah. If he married and fled, and then after a time returned and lived with his wife, there is no problem. If he completed kiddushin (i.e. he gave a ring but did not perform the chupa ceremony) with a pregnant or breastfeeding woman, we do not force him to divorce, but he may not complete the marriage (i.e. nisuin - with chupa) until after the time of breastfeeding or until the child dies. Note: Some say that there is no difference between kiddushin and nisuin (most adjudicators), and this is primary. See supra se'if 10 how to act.
A widow who was breastfeeding her child may say, "I will not breastfeed except for wages." And she may claim her ketuba immediately even though she may not marry until the end of 24 months. Rema: And there is no difference whether she [actually] started to breastfeed or not (Maharam Padua Chap. 30, Mahariv, Rivash, and Responsa Rosh rule 53).
That which we said [se'if 11] regarding a divorcee [that a man should not marry a woman who is breastfeeding], there is an authority who says that it applies only when she breastfed the child prior to her divorce to the point where he [the infant] recognized her. However, before this time the rule does not apply, because if she so desired, she would not be compelled to breastfeed him at all [after the divorce], even for payment. Another authority [disagrees and] says that a woman whose husband died, leaving her pregnant, and she gave birth and did not breastfeed her child, she still has to wait 24 months before remarrying, and it can be inferred from this opinion that the same rule would apply to a divorcee.