Researchers are to present findings that show perinatal outcomes of frozen/thawed embryo replacement (FER) have better outcomes compared with fresh in vitro fertilisation (IVF), but worse outcomes compared to the non-IVF general population.
The study, which was carried out by Ulla-Britt Wennerholm and her associates, analysed the outcomes of FER in IVF programmes compared with spontaneous conceptions and fresh IVF.
It will be showcased at the Society for Maternal-Fetal Medicine’s annual meeting, The Pregnancy Meeting, on February 14 in San Francisco.
Dr Wennerholm, of Sahlgrenska University Hospital, and her team collected data from all IVF treatments in Denmark, Norway and Sweden between 1984 and 2007, and then cross-linked them with the Nordic Medical Birth Registries.
Babies born after FER (6,653) were compared with those born after fresh IVF (42,287) and the general population (288,868).
Low birth weight (LBW), very low birth weight (very LBW), preterm birth (PTB), very preterm birth (very PTB), small for gestational age (SGA), macrosomia (excessive birth weight), large for gestational age (LGA), and stillbirth were the eight outcomes that researchers looked out for.
Children born after FER were found to have higher rates of PTB, very PTB, LBW, very LBW, LGA, and macrosomia compared with spontaneous conceptions. However, when compared with fresh IVF births, children born after FER had lower rates of PTB, LBW, and SGA.
Researchers also discovered that children born after FER had higher rates of LGA and macrosomia than those born from fresh IVF.
However, they believe the higher rates of LGA and macrosomia compared with fresh IVF will require further attention.