Blighted ovum is a form of early miscarriage which is common in both naturally and IVF conceived pregnancies.  Miscarriage is a natural process if the conception is not viable and it cannot be prevented.
Azoospermia is the complete absence of sperm in the ejaculate.  From your description of low count, motility and morphology your husband has oligoasthenoteratozoospermia.  This would require treatment using ICSI.