- To investigate pregnancy outcome of patients with dermoid and other benign ovarian cysts. A population-based study comparing all pregnancies of women with and without benign ovarian cysts was conducted. Deliveries occurred during the years 1988-2007 at Soroka University Medical Center. A multivariate logistic regression model, with backward elimination, was constructed to find independent risk factors associated with benign ovarian cysts. During the study period there were 212,114 deliveries, of which 93 occurred in patients with benign ovarian cysts. Most of the lesions were benign cyatadenoma (41.9%), 36.7% were dermoid cyst, and 11.8% were adenofibroma, mostly diagnosed during cesarean delivery (76.3%). Others (12.9%) were diagnosed during pregnancy by ultrasonography and the remaining 10.8% were diagnosed before pregnancy. The mean diameter at diagnosis was 9.05+/-7.6 cm for cystadenoma, 6.09+/-3.0 cm for dermoid cyst and 4.55+/-4.1 cm for adenofibroma. Only 3 cases of ovarian torsion were noted (3.2%), and 15 cases of hospitalization due to abdominal pain (16.2%). The following conditions were significantly associated with benign ovarian cysts: hypertensive disorder [odds ratio (OR) 3.05; 95% confidence interval (CI) 1.87-4.97], and maternal age (OR 1.04; 95% CI 1.01-1.07). Ovarian dermoid cyst was significantly associated with fertility treatments (8.6 vs. 2.4% OR=3.75; 95% CI 1.1-12.2; P=0.019). In addition, after controlling for maternal age using a multivariate analysis, fertility treatments remained significantly associated with ovarian dermoid. No significant differences were noted between the groups regarding perinatal outcomes such as birth weight, low birth weight, congenital malformations, low Apgar scores, or perinatal mortality. The course of pregnancy of patients with dermoid and other benign ovarian cysts, including perinatal outcomes, is favorable. The cysts should be managed conservatively if possible with routine ultrasound follow up during the pregnancy since complications are extremely rare.