This chapter discusses the factors associated with miscarriage following in-vitro fertilization (IVF) and outlines an evidence-based approach to counseling such couples. The risk of miscarriage dramatically increased with advancing maternal age, primarily due to trisomy. Studies on preimplantation embryos show a high rate of numeric chromosome errors in embryos produced through IVF. Embryoscopy studies of the miscarriage prior to uterine evacuation reveal that major embryonic developmental abnormalities are often seen in euploid miscarriages. Several studies have shown that hydrosalpinx is associated with an increased miscarriage rate in IVF, compared with control patients with other infertility factors. Several endocrine factors, most notably thyroid disease, are also linked to an increased miscarriage risk after IVF. Successful implantation and pregnancy depends on a complex interaction between the developing endometrium and the embryo. Performing cytogenetic analysis on the miscarriage tissue is useful for counseling the patient and for determining whether further evaluation is warranted.