It is for that reason that cytogenetic studies are appropriate in couples with apparent subfertility of long duration. Spontaneous abortion of recognized pregnancies has been far better studied. Intrauterine death between the time of pregnancy recognition and twelve gestational weeks are usually classed together. Most of these arise from accidental, nondisjunctional processes in egg or sperm formation. Given that more than a quarter of recognized pregnancies end in miscarriage, extensive assessment is probably not warranted.
Morphological evaluation appears to be of little benefit in assessing possibilities for recurrence.
Rarely, a translocational aberration will be discovered which implies very high risks in next pregnancies. While justifiable, routine cytogenetic testing in these circumstances has not become a usual standard of care. Only when three or more first trimester spontaneous abortions have occurred do most physicians feel that comprehensive assessment is justified. This justification is principally numerical. Such assessments usually include chromosomal evaluation of both parents, hormonal, endocrinologic and immune assessment of the mother, consideration of structural uterine studies etc.