Endometriosis, assisted reproduction technology, and risk of adverse pregnancy outcome.

BACKGROUND Endometriosis, a common gynaecological disease, is characterized by local and systemic inflammation, which may cause infertility and consequently, increased utilization of assisted reproduction technology (ART). We aimed to estimate the risk for preterm birth, small-for-gestational-age (SGA) birth, stillbirth, Caesarean section, pre-eclampsia and antepartal haemorrhage among women with a previous diagnosis of endometriosis compared with women with no previous diagnosis of endometriosis. METHODS In a nationwide Swedish study including 1,442,675 singleton births we assessed the association between adverse pregnancy outcome, ART and a previous diagnosis of endometriosis. Information was obtained by linkage of data between 1992 and 2006 in the Medical Birth Register with the Patient Register between 1964 and 2006. RESULTS There were 13,090 singleton births among 8922 women diagnosed with endometriosis. Compared with women without endometriosis, women with endometriosis had higher risks of preterm birth [adjusted odds ratio 1.33, 95% confidence interval (CI), 1.23-1.44]. Among women with endometriosis 11.9% conceived after ART compared with 1.4% of women without endometriosis. The risk of preterm birth associated with endometriosis among women with ART was 1.24 (95% CI, 0.99-1.57), and among women without ART 1.37 (95% CI, 1.25-1.50). Women with endometriosis had higher risks of antepartal bleeding/placental complications, pre-eclampsia and Caesarean section. There was no association between endometriosis and risk of SGA-birth or stillbirth. CONCLUSIONS Endometriosis appears to be a risk factor for preterm birth, irrespective of ART. Women with endometriosis may be more likely to be delivered by Caesarean section and to suffer from antepartal haemorrhage/placental complications and pre-eclampsia.