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.