Abstract: The halachic implications of a spontaneous abortion depend on the age of the fetus. A miscarriage within 40 days post conception is treated as similar to a menstrual period. After this point, it is treated according to the laws of childbirth.
Discussion: The halachic implications of a spontaneous abortion depend on the stage of pregnancy at which it occurs.If a woman miscarries within 40 days after mikveh immersion (generally about 7.5 weeks from her last menstrual period), then she is considered a niddah and follows the usual procedure of counting seven clean days and immersing in a mikveh.
If the spontaneous abortion takes place more than 40 days after she last used the mikveh, the woman is considered a yoledet (a woman who gave birth). If the fetus is known to be a male, then she follows the same procedure as a niddah. She can attempt a hefsek taharah on day 5, and, if the bleeding has ceased, can immerse as early as the end of day 12. If the fetus is known to be female, or if the sex is unknown (as is common in early miscarriages ), then she follows the same procedures but may not immerse before the end of day 14.
In general, date of the onset of the miscarriage from a halachic perspective is calculated from the onset of bleeding. In cases where there is a significant gap between the end of the pregnancy as diagnosed on ultrasound and the onset of bleeding , an individual question should be asked.
In all cases, the decision between performing a D&C, watchful waiting, or managing the situation medically should be made on medical grounds  . However, some rabbis will request that the diagnosis of an unviable fetus be made on the basis of repeat ultrasounds to prevent inadvertent abortion of a viable fetus.
The woman will remain niddah until the cessation of all bleeding and for at least an additional seven days. The couple should be counseled as to how long post miscarriage or D & C bleeding is expected to continue . The issue of how long the couple should wait before attempting to become pregnant again should be addressed   , as well as any possible contraindications to particular birth control methods  .
Implications for Patient Care: Spontaneous abortion within 40 days post conception renders a woman niddah. No physical contact is allowed between the couple until all bleeding has ceased and an additional seven days have passed. The minimum duration of the niddah status is 12 days.
If the miscarriage takes place more than 40 days post conception, there may be a minimum of 14 days before immersion if the fetus was a girl or the gender is not known.
Expected length of post miscarriage bleeding, and contraceptive needs and methods, should be discussed with the couple.
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