Impact of infertility characteristics and treatment modalities on singleton pregnancies after assisted reproduction.

Obstetric and neonatal outcomes of assisted reproduction and control singletons were evaluated after taking into account treatment characteristics and infertility background. The elective single embryo transfer (eSET) group (n = 45) was compared with the compulsory single embryo transfer (cSET; n = 52), double embryo transfer (DET; n = 227) and control (n = 304) groups. Infertility-related prognostic factors for neonatal outcomes were also analysed. Data were collected with structured questionnaires at gestational week 20 and 8 weeks after delivery. Spontaneous onset of delivery was more typical of the eSET group than of cSET and DET groups (68.9 versus 52.0%, P = 0.02). Mean (+/-SD) gestation at birth (39.3 +/- 1.6 weeks) and mean birth weight (3,470 +/- 505 g) of eSET singletons were comparable with other assisted reproduction groups, but gestational duration was lower than in the eSET group than in the control group (39.9 +/- 1.4; P < 0.05). However, numbers of preterm births and low birth weight infants were similar between groups. History of induced abortion increased risk of preterm birth (OR 4.5 and 95% CI 1.2-17.1) in assisted reproduction singletons. A small though clinically unimportant difference in gestational age at birth and birth weight between assisted reproduction and control singletons was found regardless of the number of embryos transferred.