In the name of Allah, Most Beneficent, Most Merciful.
What is the punishment for killing a believer? The following Verse is relevant.
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S4 V93: If a man kills a believer intentionally his recompense is Hell to abide therein (for ever): and the wrath and curse of Allah are upon him and a dreadful penalty is prepared for him.
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When a pregnant mother aborts, her action is intentional. Does she get punished in Hell because she aborted her child? It depends on the age of the fetus. Up to 120 days of conception, the fetus is simply a piece of flesh as defined in the following Tradition found in
http://www.searchtruth.com/searchHadith.php?keyword=womb soul ultimately&translator=1&search=1&book=&start=0&search_word=all&records_display=10
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Narrated 'Abdullah bin Mas'ud: Allah's Apostle the true and truly inspired, narrated to us, "The creation of everyone of you starts with the process of collecting the material for his body within forty days and forty nights in the womb of his mother. Then he becomes a clot of thick blood for a similar period (40 days) and then he becomes like a piece of flesh for a similar period. Then an angel is sent to him (by Allah) and the angel is allowed (ordered) to write four things; his livelihood, his (date of) death, his deeds, and whether he will be a wretched one or a blessed one (in the Hereafter) and then the soul is breathed into him. So one of you may do (good) deeds characteristic of the people of Paradise so much that there is nothing except a cubit between him and Paradise but then what has been written for him decides his behavior and he starts doing (evil) deeds characteristic of the people of Hell (Fire) and (ultimately) enters Hell (Fire); and one of you may do (evil) deeds characteristic of the people of Hell (Fire) so much so that there is nothing except a cubit between him and Hell (Fire), then what has been written for him decides his behavior and he starts doing (good) deeds characteristic of the people of Paradise and ultimately) enters Paradise." (See Hadith No. 430, Vol. 4) (Book #93, Hadith #546)
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The first 40 days the material for the body is collected. There is no life during the first 40 days. The next 40 days the baby is simply a clot of thick blood. Hence, there is no life during the first 80 days of conception. During the next 40 days it is simply a piece of flesh. There is life only after the soul is breathed in. Until 120 days of conception is over, the womb does not carry any life. Thus, a pregnant Muslim woman does not incur any sin by aborting within 120 days – until 119 days – of conception.
Any abortion performed on or after 120 days of conception is the same as the intentional murder of a believer, and thus the aborting mother runs the risk of landing in Hell.