Its definately both parents that shouldnt be smoking. I found this in some research
Full-sized infants cosleeping with a smoking parent showed nearly 8 times the risk is SIDS as sleeping alongside non-smoking parents.
And also found this reasoning which can be applied to both the mother and father i imagine
According to Dr. William Sears, author of "SIDS: A Parent's Guide to Understanding and Preventing Sudden Infant Death Syndrome", "mothers who smoke have lower levels of prolactin, the hormone that regulates milk production and affects mothering behavior." He goes on to say: "Diminished maternal awareness of an infant's needs has been implicated as a risk factor of SIDS, and a mother with less prolactin going through her may have less awareness of her infant, an especially worrisome situation when one considers that these infants are already compromised due to their exposure to smoke and nicotine."
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