Obstetric outcome after in vitro fertilization with single or double embryo transfer.

BACKGROUND IVF children, including singletons, are known to have a poorer obstetric outcome than children born after spontaneous conception. With a broad introduction of single embryo transfer (SET), this scenario might change. This study compares the obstetric outcome after IVF with SET, elective SET (eSET), non elective SET (non-eSET) and double embryo transfer (DET) with outcomes in the general population. METHODS All IVF children born in Sweden after IVF treatment during the years 2002-2006 (n = 13 544 children) were included and compared with all non-IVF children born during the same time period (n = 587 009 children). Data were collected from all 16 Swedish IVF clinics and cross-linked with the Swedish Medical Birth Registry. Main outcomes were preterm birth (<28, <32 and <37 w), very-low-birthweight (VLBW) and low-birthweight (LBW). Adjusted odds ratios were calculated. RESULTS In total, 7763 children were born after SET and 5724 children after DET. Comparing all SET children, irrespective of multiplicity, with all children in the general population, significantly higher rates of <28 w was found for the IVF children. Comparing IVF singletons, irrespective of SET and DET with non-IVF singletons from the general population, significantly higher rates of <28 w, <37 w, LBW and VLBW were found. eSET singletons, compared with singletons in the general population, had a significantly higher rate of <37 w and non-eSET singletons had significantly higher rates of <28 w and <2500 g births. CONCLUSIONS Children born after IVF had a poorer obstetric outcome compared with children from the general population. Singletons, when analysed as one group, irrespective of whether the children were born after eSET, non-eSET or DET, also had a poorer obstetric outcome with higher rates of preterm and LBW compared with singletons in the general population.