Obstetric outcome in patients with unexplained infertility: Comparison of treatment-related and spontaneous pregnancies

Background The aim of this study was to determine the long-term prognosis of fecundity among couples with unexplained infertility and to compare pregnancy course and outcome in spontaneous versus treatment-related pregnancies. Methods. A prospective follow-up study of 70 couples with a diagnosis of unexplained infertility. All couples had participated in a study at the Helsinki University Central Hospital where the effectiveness was compared with intrauterine insemination, direct intraperitoneal insemination or timed intercourse, each combined with superovulation. The follow-up was carried out by collecting all available information on treatment-related and spontaneous pregnancies from hospital records and questionnaires mailed to these same women 6 years later. Results. Of 70 couples, 45 (64.3%), conceived during the follow-up period. Of all 83 pregnancies, 50 (60.2%) began spontaneously and 33 (39.8%) with infertility treatment. Rate of multiple deliveries was 25% in treatment-related pregnancies, but only 2.8% in spontaneous pregnancies (p<0.05). Mean birthweight among singleton pregnancies was 3 120 grams in treatment-related, and 3 387 grams in spontaneous pregnancies (p<0.05). The rate of small-for-gestational-age (<-2 s.d.) and preterm births (before 37 completed weeks) in both groups was equal. Conclusions. The long-term prognosis of couples with unexplained infertility was good, and many of the pregnancies began spontaneously. The birthweight of singleton neonates in treatment-related pregnancies was lower than in spontaneously conceived pregnancies, but otherwise perinatal outcome was similar.