Dados do Trabalho

Title

Is there any difference between neonatal outcomes from twin pregnancies according to its conception method?

Objective

To compare neonatal outcomes from twin pregnancies according to reproductive techniques and spontaneous pregnancies (SP).

Methods

A retrospective observational study was performed in a reproductive medicine center and in a maternal child public hospital, both located in South of Brazil. Data regarding reproductive techniques were collected from 1990-2022 and regarding SP from 2021-2022. A total of 875 live births' twin pregnancies resulting from reproductive techniques were included in addition to 80 live birth's twin pregnancies resulting from SP, all divided into 4 groups according to conception: G1, In vitro fertilization embryo transfer (IVF-ET; n= 635) vs. G2, frozen embryo transfer (FET; n= 218) vs. G3, ovulation induction/artificial insemination (OI/AI; n= 22) vs. G4, SP (n=80). Regarding reproductive techniques, all cycles with embryo biopsy, freezing oocytes or received donated oocytes were excluded to avoid bias. Considering an alpha 0.05, the total sample was deemed with 80% of statistical power. Variables regarding neonatal outcomes were compared between groups, expressed as mean±SD, median[IQR] or n(%), as appropriate. Anova and Kruskal-Wallis tests were applied, considering p<0.05.

Results

Comparing groups 1 vs. 2 vs. 3 vs. 4, the following results were found, respectively: maternal age, yo (33.8±3.8 vs. 34.3±3.7 vs. 32.3±3.4 vs. 26.8±7.2, p=0.000); first newborn's weight, g (2262.8±559.5 vs. 2336.6±592.7 vs. 2371.5±603.3 vs. 2112.3±615.9, p=0.030); second newborn's weight, g (2197.8±548.1 vs. 2318.4±568.8 vs. 2181.3±478.5 vs. 2002.4±681.6, p=0.000); newborn's birth weight difference, g (235 [100-420] vs. 250 [100-410] vs. 217.5 [100-470] vs. 310 [125-470], p=0.114); n%: prematurity, % (66.5 vs. 69.3 vs. 54.6 vs. 81.3, p=0.027); first newborn's Apgar 5thmin≥7, % (97.4 vs. 95.4 vs. 95.4 vs. 78.7, p=0.042); second newborn's Apgar 5thmin≥7, % (95.9 vs. 95.4 vs. 95.4 vs. 76.2, p=0.030); C-section, % (96.8 vs. 99.0 vs. 95.4 vs. 77.5, p<0.001).

Conclusion

Previous studies have already shown differences in singleton pregnancies' neonatal outcomes regarding reproductive technique, but little is known when considering twin pregnancies or SP comparison. In this study, the singleton pregnancy pattern was not observed in twin pregnancies, since there was no difference in neonatal outcomes according to reproductive technique. However, twin pregnancies from SP were associated with higher prematurity rate, lower birth weight in both newborns, lower Apgar 5thmin index, even considering its lower sample size. This could be related to social economical differences among reproductive treatments' patients and SP patients from public health service, which has little prenatal care assistance. The higher C-section rate in reproductive patients also reflects this pattern, since the public health system does not allow patients to choose for elective C-section delivery, which is more associated with private patients in Brazil. Furthermore, it is important to emphasize that the public hospital included in this study is considered a local high risk pregnancy reference center, receiving most of the complicated twin pregnancies from primary health care. Thus, these results highlight the importance of better understanding the physiopathological mechanisms involved in neonatal outcomes from reproduction treatments.

Keywords

twin pregnancy, spontaneous pregnancy, neonatal outcomes