< Back to Previous Page Social and Genetic Causes of Birth Defects Some social causes of birth defects are due to the ignorance or unpreparedness of the mother for pregnancy.  These can include social habits that can wreak havoc with the unborn fetus such as alcohol abuse, smoking cigarettes, drug abuse, taking certain medications, high fat diet, obesity, not taking proper vitamins or minerals, etc.  Social causes of birth defects are not as prevalent as they once were but they still do occur.  Other causes of birth defects can be genetic factors out of the control of the mother such a difference in the RH factors of the blood type between the mother and the unborn fetus.  The RH factor of the blood determines whether the blood type is negative or positive and a difference between the pregnant mother and the unborn child can lead to birth defects. Genetic causes of birth defects do not necessarily play a part in babies born with birth defects.  In fact, most babies born with birth defects are born to healthy parents with no visible signs of any health risk factors.  Even the March of Dimes reports that nearly 60 percent of all birth defects are due to unidentified causes. The 40 percent are caused by either environmental or genetic factors or in some cases a combination of the two factors can play a role in the cause of birth defects.  In the birth defects that are affected by genetics, one defective gene or a missing gene can lead to birth defects.  The genes that can cause birth defects are the same genes that are in the parents of the unborn fetus even if the either or both parents show no signs of the defect.  The unborn fetus will inherit all the chromosomes it needs from both its parents.  One set from each parent.  A parent that has a history or even the faulty gene for a certain disease can pass on that gene to the fetus even if the other parent passes on a normal or healthy gene.  This is recognized as dominant inheritance birth defects. Some forms of dominant inherence birth defects can include: Familial high cholesterol Huntington disease Achondroplasia Glaucoma Polydactyly Marfan syndrome