Original ResearchObstetricsNeonatal and maternal outcome after blastocyst transfer: a population-based registry study
Introduction
Worldwide, the use of assisted reproductive therapy (ART) is expanding, and the number of children born through ART has passed 6 million. In Sweden, around 4000 children are born through ART each year and they comprise today 3.6% of the total national birth cohort in Sweden.1
In vitro fertilization (IVF) is associated with an increased risk of preterm birth (PTB) and low birthweight (LBW) as compared to spontaneous conception, which mainly can be explained by the higher incidence of multiple pregnancies.2, 3, 4 However, an increased risk of PTB, LBW, and birth defects has also been demonstrated in singleton pregnancies after IVF.4, 5, 6, 7, 8, 9
In spontaneous conception the implantation occurs 5-7 days after fertilization. In conventional IVF, the cleavage-stage embryos (day-2 to -3 embryos) are replaced in the uterus. Modern technology has made it possible to wait until the blastocyst stage (day 5-6 embryos) and then replace the embryo in the uterus. Blastocyst transfer has been shown to increase delivery rates in fresh cycles, although not cumulatively.10
Conflicting results have been reported concerning neonatal and maternal outcomes after blastocyst vs cleavage-stage transfers. A systematic review and metaanalysis showed an increased risk of PTB (<37 gestational weeks) (4 studies) and birth defects (2 studies) when using blastocyst transfer.11 Other recent studies from Australia and Japan showed no significant differences in PTB or LBW between singletons from blastocyst and cleavage-stage transfers.12, 13 A previous Swedish study including 1311 singletons and multiples born after fresh and frozen blastocyst transfers, covering the years 2002 through 2006 and partially overlapping the present study, showed a significantly increased risk of birth defects as compared to children born after cleavage-stage transfer.14 However, in a Canadian study covering the years 2001 through 2009 including 3206 singletons after fresh blastocyst transfer there was no increased risk of birth defects after blastocyst transfer.15
Few studies have reported on maternal outcomes after blastocyst vs cleavage-stage transfers. A Swedish registry study, covering the years 2002 through 2006 and partially overlapping the present study, showed increased risk of placenta previa in singleton pregnancies from fresh blastocyst vs fresh day-2 to day-3 transfers.16 However, other studies have shown no significant differences in placental complications.13, 17, 18
The aim of this study was to examine neonatal and maternal outcomes in singleton deliveries after blastocyst transfer in Sweden from 2002 through 2013, and compare these deliveries with all singleton deliveries after cleavage-stage transfer and after spontaneous conception during the same period of time.
Section snippets
Study design
This study was a population-based retrospective registry study carried out in Sweden. We collected data from all IVF clinics, both public and private, in Sweden on IVF treatments performed from 2002 through 2013. The IVF clinics reported data on deliveries to the Swedish National Board of Health and Welfare for years 2002 through 2006, and for years 2007 through 2013, to the National Registry of Assisted Reproduction.1 All reported IVF singleton and twin deliveries with autologous oocytes were
Results
In total, 4819 singletons were born after blastocyst transfer, 62.8% after fresh and 37.2% after frozen embryo transfer. There were 25,747 singletons born after cleavage-stage transfer, 76.7% after fresh and 23.3% after frozen embryo transfer.
There were 295 multiple births after blastocyst transfer (76.6% fresh, 23.4% frozen) and 1937 after cleavage-stage transfer (78.0% fresh, 22.0% frozen), giving a multiple birth rate of 5.8% (295/5114) and 7.0% (1937/27,684), respectively.
In the general
Principal findings
The main finding of this large retrospective population-based registry study was that no significant difference in the rate of birth defects was found between singletons born after blastocyst transfers and singletons born after cleavage-stage transfers. Perinatal mortality and rates of placental complications were significantly higher in singletons born after blastocyst transfers as compared with singletons born after cleavage-stage transfer.
Meaning of the findings in relation to other studies
The finding of no increase in birth defects differ
Acknowledgment
The authors want to express their thanks to all in vitro fertilization clinics in Sweden that provided in vitro fertilization data.
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2022, European Journal of Obstetrics and Gynecology and Reproductive BiologyCitation Excerpt :However, a number of studies have drawn conflicting conclusions. These studies found that in fresh embryo transfer cycles, blastocyst transfer increased the risk of PTB, very preterm birth (VPTB) and LBW, but decreased the risk of SGA [13–15]. A meta-analysis published recently by Zeng et al. found that blastocyst transfer had no adverse effects on pregnancy outcomes in FET cycles compared with cleavage-stage embryo transfer [16].
Society for Maternal-Fetal Medicine Consult Series #60: Management of pregnancies resulting from in vitro fertilization
2022, American Journal of Obstetrics and Gynecology
This study was supported by grants from Swedish Association of Local Authorities and Regions and the University of Gothenburg/Sahlgrenska University Hospital (LUA/ALF 70940).
The authors report no conflict of interest.
Cite this article as: Ginström Ernstad E, Bergh C, Khatibi A, et al. Neonatal and maternal outcome after blastocyst transfer: a population-based registry study. Am J Obstet Gynecol 2016;214:378.e1-10.