Comparison of frozen-thaw blastocyst transfer strategies in women aged 35–40 years: a retrospective study

Abstract

ObjectiveTo compare the effects of five different frozen-thaw embryo transfer (FET) strategies in women aged 35–40 years.MethodsData from 1,060 patients were divided into five groups according to the number and quality of transferred blastocysts: a high-quality single blastocyst group (group A, n= 303), a high-quality double blastocysts group (group B, n= 176), a high-quality plus poor-quality double blastocysts group (group C, n= 273), a poor-quality double blastocysts group (group D, n= 189), and a poor-quality single blastocyst group (group E, n= 119). Comparative analyses were then performed between groups with regard to primary conditions, pregnancy, and neonatal outcomes.ResultsGroup A had the lowest twin pregnancy rate (1.97%) and incidence of low-birth-weight infants (3.45%), which were significantly different from groups B, C, and D. In addition, the preterm birth rate (7.89%), neonatal birth weight (3300 g [3000, 3637.5]), and neonatal birth age (39.14 weeks [38.43, 39.61]) in group A were different from those in groups B and C. Double blastocyst transfer (DBT) was associated with a 20.558-fold (Risk Ratio [RR]=20.558, 95% confidence interval [CI], 6.628–63.763) and 3.091-fold (RR=3.091, 95% CI, 1.69–5.653) increased risk of twin pregnancy and preterm delivery in unadjusted analysis, respectively, when compared with single blastocyst transfer (SBT). In the adjusted analysis, we observed similar risk estimates (adjusted RR=26.501, 95% CI, 8.503–82.592; adjusted RR=3.586, 95% CI, 1.899–6.769).ConclusionAlthough, high-quality SBT resulted in a lower live birth rate than high-quality DBT, it also significantly reduced the risk of adverse pregnancies, thus resulting in more benefits for both the mother and baby. Collectively, our data indicate that high-quality SBT remains the optimal FET strategy for women aged 35–40 years and warrants further clinical application.

Comparison of pregnancy outcomes among patients of different ages who underwent frozen-thawed high-quality single blastocyst transfer

“…Age is one of the most important factors in choosing an embryo transfer strategy. A meta-analysis showed that high-quality SET is the first choice for women under 40 years of age [ 10 ], which coincides with previous studies by our team [ 4 , 5 ]. However, some studies suggest that the best pregnancy outcomes can be obtained by transferring a single blastocyst in individuals under 35 years old and 35–37 years old; while, for individuals aged 38–40 years and older, DET has better perinatal outcomes than SET [ 11 ].…”

“…Our team previously conducted a study on the number and type of blastocysts transferred and found that high-quality SBT was the optimal frozen-thawed embryo transfer (FET) strategy for young women [ 4 ]. Although this strategy is still feasible for patients aged 35–40 years [ 5 ], there were some limitations in the previous study; for example, women of advanced age were not stratified, and it is impossible to determine whether the benefits of SBT are the same for women aged 35–37 years and older. To our knowledge, no studies have explored on age stratification in frozen-thawed high-quality SBT.…”