Insufficient or excessive hormonal levels usually result in spontaneous abortion before 10 weeks gestation. Infectious, immunologic, and environmental factors generally are seen in first-trimester pregnancy loss. Anatomic factors usually are associated with second-trimester loss. Surveillance data from the US between 1987 and 1990 revealed a total of 1459 pregnancy-related deaths. Age and increased parity affect a woman's risk of a miscarriage.
Age primarily affects the oocyte.
When oocytes from young women are used to create embryos for transfer to older recipients, implantation and pregnancy rates mimic those seen in younger women. The number of miscarriages and chromosomal anomalies decreases, suggesting that the uterus is not responsible for poor outcomes in women of advanced reproductive age. On pelvic examination, the cervix should be closed, and the uterus should be contracted. If adnexal tenderness is present, suspect the presence of an ectopic pregnancy. Trisomy chromosomes commonly are encountered.