Children born after cryopreservation of embryos or oocytes: a systematic review of outcome data

Background Children born from fresh in vitro fertilization (IVF) cycles are at greater risk of being born smaller and earlier, even when limited to singletons; those born from frozen cycles have an increased risk of large-for-gestational age (LGA) birthweight (z-score ≥1.28). This analysis sought to overcome limitations in other studies by using pairs of siblings, and accounting for prior cycle outcomes, maternal characteristics, and embryo state and stage. LGAwas 9.2-9.8 and 14.2-15.4% in 1st and 2nd births in fresh cycles, and 13.1-15.8 and 20.8-21.0% in 1st and 2nd births in frozen cycles. The risk of LGAwas increased in frozen cycles (1st births, adjusted odds ratios (AOR) 1.74, 95% CI 1.45, 2.08; and in 2nd births when the 1st birth was not LGA, AOR 1.70, 95% CI 1.46, 1.98 for fresh/frozen and 1.40, 1.11, 1.78 for frozen/frozen). Conclusions Our results with siblings indicate that frozen embryo state is associated with an increased risk for LGA. The implications of these findings for childhood health and risk of obesity are unclear, and warrant further investigation.

Section: Discussionmentioning

confidence: 99%

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

Luke

Brown

Wantman³

et al. 2016

“…The low birthweight rate among singletons was 18 % and among multiple 80 %. The premature delivery rate was 26 % for singletons and 71 % for multiple pregnancies [43]. However, long-term child follow-up studies are lacking.…”

Section: Discussionmentioning

confidence: 99%

Accumulation of oocytes from a few modified natural cycles to improve IVF results: a pilot study

Greco

Litwicka

Arrivi

et al. 2013

Purpose To evaluate the role of co-transfer of embryos derived from vitrified oocytes accumulated during the previous modified natural cycles and an embryo developed from the last one as an alternative to repetitive single embryo transfer in a fresh modified natural cycle. Methods Thirty-six patients underwent ICSI procedure with three frozen natural oocytes supplemented by a fresh one obtained from the fourth modified natural cycle. Thirty-one controls received at least three consecutive single embryo transfer in a fresh modified natural cycle. Results In the study group the oocyte retrieval, survival and total fertilization rate were 73.0 %, 78.1 %, and 64.5 %, respectively. Fifty-two embryos were transferred in 29 transfers. In the control group the oocyte retrieval and fertilization rate was 77.4 % and 83.7 %, respectively. Fifty single embryo transfers were performed. Of a total 14 pregnancies obtained in the study group 10 were defined as clinical and 4 as abortions. In the control group a total of 8 single clinical pregnancies and 2 miscarriages were encountered. The overall (20.0 % vs 48.2 %) and the clinical (16.0 % vs 34.4 %) pregnancy rate were significantly higher in the study group having cumulative embryo transfer following the oocyte accumulation. Conclusions These data demonstrate that the co-transfer of embryos derived from vitrified oocytes accumulated during the previous modified natural cycles and an embryo developed from the last fresh modified natural cycle assure an excellent clinical outcome with the overall and clinical pregnancy rate significantly higher compared to the repetitive single embryo transfer in a fresh modified natural cycle.

“…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].…”

Section: Introductionmentioning

confidence: 99%

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

Korošec

Frangež

Steblovnik

et al. 2015

Purpose Higher risk for birth of singletons being large for gestational age (LGA) has been revealed after in vitro fertilization (IVF) frozen-thawed embryo-transfer (FET). This phenomenon is now being investigated, since there is a speculation that these neonates could suffer from underlying epigenetic disturbances. The aim of the study was to expose independent LGA risk factors and to identify those connected to the IVF techniques. Methods Altogether, 4508 singleton pregnancies and births were included in the cohort case-matched study. Two hundred eleven singleton pregnancies and births after FET and 916 after fresh embryo transfer (ET) were included into two study groups. The IVF procedures were performed at the University Medical Centre Ljubljana between 2004 and 2011. For each IVF pregnancy, three matched consecutive controls after natural conception were included. Using logistic regression models, we observed LGA connection to maternal parameters (smoking, hypertension, parity, BMI, gestational diabetes, IVF conception, FET, double ET, and ICSI procedure).Results Singletons born after FET had a significantly higher risk for being LGA (p=0.032; OR 1.697; 95 % CI 1.047-2.752). BMI 25-30 was a significant independent risk factor for LGA in the IVF groups (FET p=0.041, OR 2.460, 95 % CI 1.030-5.857 and fresh ET p=0.003; OR 2.188, 95 % CI 1.297-3.691). ICSI and double ET had no significant effect on LGA occurrence. Conclusions Besides maternal BMI, FET is a significant independent LGA risk factor in IVF patients. Other observed factors (smoking, hypertension, multiparity, GDM, ICSI procedure, or number of embryos transferred) do not influence LGA risk significantly.