Background: Few studies have investigated the association between subfertility in women and factors in early life such as birth weight and age at menarche, and most have produced contradictory results. In the present study, this association was investigated among women undergoing artificial reproductive techniques (ART), including IVF for reason of polycystic ovary syndrome (PCOS) or diminished ovarian reserve. Herein, PCOS included oligomenorrhoea and at least one additional symptom such as hyperandrogenism, hirsutism or polycystic ovaries on ultrasound. In most patients this was concomitant with elevated serum LH levels. Diminished ovarian reserve was defined as receiving a donated oocyte or having a low response to ovarian hyper stimulation. Methods: Among a retrospective cohort of 26 428 women diagnosed with subfertility between 1980 and 1995, three study groups and one reference group were defined using data from medical records. Women were included in the first group if diagnosed as having PCOS (n = 265). In order to define diminished ovarian reserve capacity, two groups were selected: (i) women receiving a donated oocyte (n = 98); and (ii) women having a low response (three follicles or less) to ovarian hyperstimulation in both their first and second IVF cycles (n = 351). Women with tubal obstruction formed the reference group (n = 957). In a logistic regression model, the effect of birth weight and age at menarche was examined. Information on both variables was obtained from mailed questionnaires. Results: Birth weight did not differ significantly between the study groups and the reference group. However, PCOS patients were significantly older at menarche [OR 3.31 (2.18-5.04)]. Women receiving a donated oocyte and low responders were significantly younger at menarche [OR 2.67 (1.35-5.29) and OR 2.01 (1.26-3.20) respectively]. Conclusion: The fetal origins hypothesis, the association between intrauterine growth retardation and disease in adult life, could not be confirmed, though a relationship between timing of menarche and PCOS and a diminished ovarian reserve was identified. Further investigation of the effect of birth weight on fertility outcome in a prospective setting is strongly advised.