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Date of last update: 10/14/2017.

Forum Name: Gynecology

Question: Risks of marrying cousin

 IANBD - Wed Mar 25, 2009 5:00 am

Hello, i've decided to marry my aunt's (mother's sister) son. my aunt is also been married to her cousin (uncle's son). anyways, i've been under immense pressure from my relatives for deciding to marry my cousin. because there are already a few couples in our family who are cousins. moreover in most cases, such couples get defective babies. i've heard that there are some tests which can be done to avoid these risks. does blood group play any role in having defective child? or is there really any way to predetermine that the baby born will be defective? what measures can we take before or after marriage to avoid these risks?
 Debbie Miller, RN - Thu Mar 26, 2009 10:50 pm

User avatar Hello,
While there is a slight increase in risks to children born of first cousins, it is not as significant as we once thought. Now that more is known about genetics, we understand this. 3-4% of all babies are born with a birth defect. Of first cousins that risk goes to 6% so the increased risk is comparable to a woman giving birth at an advanced age - a little higher risk but not huge. Other factors can also increase your risk - in some cases simply marrying within your own race or community can. Children between brothers and sisters do have a more significant risk.

Blood types are not related to birth defects. Genetic testing can be done, especially if you have a history of genetic problems in your family which might make you at increased risk for some defects which require both parents to pass along the gene in order for it to be a problem. This testing can be very expensive. Meeting with a genetic counselor to review family history (genomics) could also be helpful if you know something about your family's past generations.

Most of the concerns are from perceived as opposed to factual risks. Many needless terminations have occurred because of this misunderstanding. In some cultures, marrying cousins is actually common and preferred.

Good luck on your marriage.

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