Pittaway, D. E., Vernon, C., & Fayez, J. A. (1988). Spontaneous abortions in women with endometriosis. Fertility and Sterility, 50(5), 711-715. https://doi.org/10.1016/s0015-0282(16)60303-5
Pittaway DE, Vernon C, Fayez JA. Spontaneous abortions in women with endometriosis. Fertil Steril. 1988;50(5):711-715. doi:10.1016/s0015-0282(16)60303-5
Pittaway, Donald E., et al. "Spontaneous abortions in women with endometriosis." Fertility and Sterility, vol. 50, no. 5, 1988, pp. 711-715.
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Endometriosis miscarriage was also common in other infertile women
A 1988 study of 350 women found more miscarriage with endometriosis than in two comparison groups. Without terminations and ectopics, 45 out of 100 ended in miscarriage. The rates were 28 out of 100 with tubal disease and 11 out of 100 in fertile women. The authors concluded most were not caused by endometriosis.
Miscarriage per pregnancy: Women with endometriosis, 45 in 100; Women with tubal disease, 28 in 100. Source: Pittaway DE et al., 1988, PMID 3181482.Study at a glance, retrospective comparison of 350 women: Endometriosis miscarriage was also common in other infertile women. Source: Pittaway DE et al., 1988, PMID 3181482.
Key Findings
Researchers analyzed pregnancy histories of 350 women seen from 1980 to 1984: 100 with endometriosis, 100 with tubal disease and 150 fertile women seeking tubal sterilization reversal.
Miscarriage affected 38% of all pregnancies with endometriosis, 19% with tubal disease and 10% in fertile women. Excluding terminations and ectopics: 45%, 28%, 11% (P < 0.01 tubal; P < 0.001 fertile).
Miscarriage frequency by severity was 39% (mild), 57% (moderate) and 41% (severe/extensive). The differences among the three severity groups were not statistically significant.
In the 1- to 2-year interval before presentation, 79% of endometriosis pregnancies ended in miscarriage. The tubal disease group had 57 to 62% across 1- to 4-year intervals, no significant difference.
After treatment, data covered 68 women with endometriosis and 59 with tubal disease. Miscarriage frequency fell significantly with endometriosis (P < 0.001), and the groups did not differ.
Interpretation
The study is retrospective and comes from one center, using interviews, questionnaires and medical records. A retrospective comparison can show association. Cause needs other designs. The authors propose that the higher rate before evaluation arises mainly from selection bias, because women with unsuccessful pregnancies more often come forward for workup. They say their data suggest that about 10% to 15% of the overall miscarriage rate with endometriosis is associated with the disease. They say whether that share reflects selection bias or a causal effect is unknown. The paper does not say which treatments the women received, and post-treatment data covered only part of each group.
RRM Context
Restorative reproductive medicine treats pregnancy loss as a question with several possible answers, and endometriosis is one candidate. The authors also checked ovulation and luteal phase problems. Those appeared in 16% of the endometriosis group and 11% of the tubal disease group, with no significant difference. Women in both infertile groups lost pregnancies at high rates.
Our editorial summary of this paper, not the article's abstract.
Abstract
Pregnancy outcomes were evaluated retrospectively in 350 women to investigate the relationship between endometriosis and spontaneous abortions. The frequency of spontaneous abortions in women with endometriosis was significantly higher than in both a fertile nonendometriosis group and an infertile group with tubal disease. There was no correlation between the severity of the endometriosis and the frequency of spontaneous abortions. After treatment, the frequency of spontaneous abortions was significantly decreased in both the endometriosis and the tubal disease group, but these values were not significantly different from each other. We conclude that high spontaneous abortion rates are a characteristic of other subgroups of women with secondary infertility and not just in women with endometriosis, and that the majority of spontaneous abortions associated with endometriosis are not caused by the condition.
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