Endometriosis, a disease associated with pelvic pain, subfertility, impaired quality of life and work productivity, affects many women around the globe. Arguably, one of the most famous sufferers was Marilyn Monroe (1926–62). Her condition was ‘so severe that it is said that it destroyed her marriages, her wish for children, her career and ultimately her life’ (Summers A, Onyx books, 1985). Not much was known about this condition until John Sampson studied the blood supply of the uterus and concluded that ‘bits of uterine mucosa, occasionally, might escape into the venous circulation during menstruation’ (Am J Pathol 1927;3:93–109). Subsequent literature focused on the gynaecological implications of the disease. The effects of endometriosis in pregnancy were not well documented until RB Scott reviewed 47 case reports and added two of his own, ascertaining risk factors in 31 of the reported cases (Am J Obstet Gynecol 1944;47:609–30). In those with adenomyosis, complications included spontaneous rupture of the uterus, postpartum haemorrhage and labour dystocia. Complications were less common with extrauterine endometriosis and included single cases of ruptured endometriotic cyst, ruptured ectopic pregnancy and dystocia. Chun (J Obstet Gynaecol Br Emp 1957;64:728–30) described similar complications when endometriosis affected the uterus. The pathophysiology of endometriosis remains poorly understood. To date, no studies have been performed on biopsies of the placental bed in women with endometriosis to investigate the possible changes in the development of the uteroplacental circulation. Several clinical studies have reported an association between endometriosis and a spectrum of pregnancy complications (Brosens et al. Fertil Steril 2012;98:30–35). However, results from the few population-based cohort studies examining this link are inconsistent, reflecting the challenges of such studies, because endometriosis can only be diagnosed with certainty by laparoscopy. Saraswat et al. (BJOG 2016;DOI: 10.1111/1471-0528.13920) reports on a population-based cohort study over a 30-year period (1981–2010) using data from the national Scottish Record Linkage system. Of a total of 42 092 women diagnosed with endometriosis by laparoscopy for the first time, 8710 were identified as having a pregnancy subsequent to the diagnosis. This cohort of women had poorer pregnancy outcomes with significantly increased risks of miscarriage, ectopic pregnancy, placenta praevia, unexplained antepartum haemorrhage, preterm birth and postpartum haemorrhage. Hypertensive disorders, placental abruption and preterm birth were not influenced by endometriosis. Rare but possible catastrophic complications of pelvic endometriosis in pregnancy, include spontaneous haemoperitoneum and gastrointestinal bleeding (Brosens et al. Fertil Steril 2012;98:30–5). Ovarian endometrioma have been reported to increase in size during pregnancy, leading to rupture, torsion or abscess formation. Although endometriosis is associated with subfertility, pregnancy conceived either spontaneously or after assisted reproduction technology is increasingly common in women with this condition. Although the exact mechanism of the obstetric complications of endometriosis are not clearly known, the associated risk factors found described in early studies are clinically sound and modern day clinicians need to be aware of these when a woman with unexplained pain or bleeding presents in pregnancy. None declared. Completed disclosure of interests form available to view online as supporting information. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.