Obstetric outcome in singletons after in vitro fertilization with cryopreserved/thawed embryos

Abstract

The obstetric outcome of singletons after cryopreservation was slightly poorer when compared with the general population. In comparison with fresh cycles, the outcome varied. The finding of an increased rate of LGA after cryopreservation requires further study.

Increased risk of large-for-gestational age birthweight in singleton siblings conceived with in vitro fertilization in frozen versus fresh cycles

“…These analyses indicate that frozen embryo state [4][5][6][7][8][9][10][11][12][13] is associated with an increased risk for LGA, and blastocyst embryo stage is associated with a decreased risk for SGA. The magnitude of the increase we found in the 2nd birthweight in the fresh/frozen pairs of siblings of +222 g is in accord with prior studies (+244 g 4 in an Australian population, +250 g 10 and +286 g 6 in Danish populations), and far exceeds the +81 g attributable only to an increase in parity.…”

“…Prior studies have also consistently reported an excess of large-for-gestational age (LGA) birthweights among children born from frozen embryos; [4][5][6][7][8][9][10][11][12] longer embryo culture of fresh embryos has also been implicated as a potential cause of LGA [13].…”

Independent factors influencing large-for-gestation birth weight in singletons born after in vitro fertilization

“…Several studies have confirmed that there are important differences in placental abnormality rates between FET and fresh ET singleton pregnancies [3,6,7,13] and that placentas after IVF are larger and heavier [28]. In a recent study, the researchers speculated that increased placental size could promote glucose delivery to LGA fetuses [48].…”

“…Several studies have shown that singletons born after FET have a perinatal outcome more comparable to those born after natural conception than to those born after fresh embryo transfer (fresh ET), having higher birth weight and less pregnancy complications [2][3][4][5][6][7][8][9][10]. However, higher risk for birth of a singleton being large for gestational age (LGA) has been revealed after FET [2,3,7,8,[11][12][13][14].…”

“…The influences of the culture media [21][22][23], culture period [24,25], hormonal protocols [26], and infertility [12,14,27] on the IVF singleton birth weight have already been considered. There are several studies confirming that IVF placentas differ from spontaneous placentas in their size, shape, weight, and abnormality rate [3,6,7,[28][29][30][31], and that placentation following FET differ from the placentation following fresh ET [3,6,7,13] In this study, we analyzed the connection of IVF procedure type and maternal background factors to LGA risk. The factors observed were the fertilization technique, ET type, number of embryos transferred, maternal age, smoking, hypertension, parity, BMI, and gestational diabetes mellitus (GDM).…”