Normal sperm has an oval head and a long tail. Abnormal sperm has head or tail defects such as a large or misshapen head or a crooked or double tail. These defects might affect the ability of the sperm to reach and penetrate an egg. This kind of infertility is also known as Teratozoospermia.  An abnormal semen analysis doesn’t mean infertility. Many men with low semen analysis values can still father children. It just might take longer. If the co-partner isn’t able to conceive through sexual intercourse, assisted reproductive technology such as In Vitro Fertilization(IVF) might be an option.