Though the<unk>  is not genetic with its cause unknown, studies have shown that there are certain factors that can increase the risk of mothers giving birth to children with these anomalies. Chromosomal abnormalities Abnormalities in chromosomes such as trisomy 18, trisomy 13, and monosomy X have been shown to be tied to this disorder. Environmental factors Mothers with poor socioeconomic conditions, poor nutrition, low parity, and lack of folic acid supplementation, and/or hyperhomocysteinemia have shown to be at larger risk. Drugs Animal studies have shown that administration of the drugs vinblastine, streptonigrin, triparano, sulfonamide, tetracycline, antihistamines, and antitumor agents to pregnant mothers have resulted in offspring born with<unk> . The drug clomiphene, a drug commonly used for ovulation stimulation in fertility treatments, has also been seen to be associated with<unk> . Obesity Studies have shown that obesity of the mother increases the risk of neural tube disorders such as<unk>  by 1.7 fold while severe obesity increases the risk by over 3 fold. History of<unk>  Once a mother has given birth to a child with<unk> , risk of reoccurrence increases to 1-5%.
Iniencephaly
Klippel–Feil syndrome
Brachyphalangy
Microhydranencephaly
Oxycephaly
Hemihydranencephaly
Anencephaly
Hydranencephaly