- Abstract Objective: To investigate pregnancy outcome in patient who conceived by assisted reproductive techniques. Methods: A retrospective population based study was conducted, comparing obstetrical complications and neonatal outcomes of singleton pregnancies conceived by in vitro fertilization (IVF; n=1,296) and ovulation induction (n=1,988) as compared to singleton pregnancies conceived spontaneously (n=172,288). Multivariable models were constructed to control for confounders. Results: A significant linear association (using the chi-square test for trends) was documented among the three groups in adverse outcomes such as gestational diabetes mellitus (17.3% in the IVF, 14.2% in the ovulation induction, 6.6% in the comparison group, p<0.001), severe preeclampsia (2.7% in the IVF, 1.8% in the ovulation induction, 1.1% in the comparison group, p<0.001) and perinatal mortality (3.3% in the IVF, 2.1% in the ovulation induction, 1.3% in the comparison group, p<0.001). In vitro fertilization and ovulation induction treatments were found to be independent risk factors for gestational diabetes mellitus, using two different multiple logistic regression models controlling for confounders such as maternal age (adjusted OR=1.77, 95% CI-1.52-2.07, P<0.001 and adjusted OR=1.93, 95% CI-1.69-2.21, P<0.001; respectively). Conclusions: Pregnancies conceiving following assisted reproductive techniques are at an increased risk for adverse obstetrics outcomes. The risk is higher for pregnancies following IVF compared with these conceived following ovulation induction.