A family history of endometriosis is one of the most important risk factors for this condition; women who have a first-degree relative with endometriosis have a 6- to 7-fold increased risk of developing the condition (Burney 2012).
Early Menarche and Never Having Been Pregnant
For women who have not had a child, experiencing menarche at an early age and having shorter menstrual periods are associated with an increased risk of endometriosis. Alternatively, for mothers, number of children and length of lactation are associated with a decreased risk of endometriosis (Missmer 2004). Also, menarche after age 14 appears to greatly reduce risk of endometriosis (Treloar 2010). Women who have never had children (nulliparity) are also at an increased risk (Schenken 2013). However, because endometriosis can cause infertility, nulliparity may in part be a sign rather than a risk factor for endometriosis.
Lifestyle, Dietary, and Environmental Risk Factors
Exposure to certain pesticides (eg, organochlorine) may also increase the risk of endometriosis (Cooney 2010; Buck Louis 2012). Women with endometriosis tend to have a lower body mass index (BMI) (Hediger 2005); however, women who get more physical activity may be at a slightly reduced risk of developing endometriosis (Vitonis 2010). Diet may also play a role, as some research has suggested that a diet low in vegetables and omega-3 fatty acids and high in red meat and trans fats may increase the risk of endometriosis (Parazzini 2013; Missmer 2010).