Adverse Neonatal Outcomes of Twin Gestations: Do They Differ By Mode of Conception?

Abstract

Background: The number of fertility treatments and consequently, the number of births conceived through fertility treatments, has continued to increase in the United States. Treatments, including assisted reproductive technology (ART) and non-ART treatments such as fertility-enhancing drugs, make conceiving a child possible for those who face infertility. However, fertility treatments are associated with a higher rate of multifetal gestations which are known to come with greater adverse outcomes. However, there is more to understand on if multifetal gestations conceived with fertility treatments pose an even greater risk than singleton gestations. In our study, we examined neonatal outcomes among twin gestations conceived through spontaneously, non-ART treatments, or ART. Methods: We utilized linked vital statistics-patient discharge data from California (2007-2011) and included twins with gestational ages of 23-42 weeks. We categorized mode of conception into three categories- spontaneous or non-ART or ART. We compared demographics and outcomes (NICU admission >24 hours, respiratory distress syndrome, macrosomia, small for gestational age, congenital anomalies, intrauterine fetal demise (IUFD), and infant death) using chi-square tests. Multivariable logistic regression models then assessed the association of mode of conception with the outcomes. Results: Among 64,500 neonates, 88.0% were spontaneous gestations, 9.0% were ART gestations, and 2.93% were non-ART treatment gestations. Pregnant patients who used fertility enhancing drugs or ART were more likely to be white, older, highly educated, on private insurance and have normal BMI (p<0.001 for all). Multivariable logistic regression showed that pregnancies conceived through fertility enhancing drugs had significantly higher odds of NICU admission [aOR=1.41 (1.28,1.56)] and respiratory distress syndrome [aOR=1.27 (1.15,1.42)]. Similar results were found in pregnancies conceived through ART, but ART also had higher odds of infant death [aOR=1.35 (1.03,1.78)] and congenital anomalies [aOR=1.11 (1.02,1.21)]. Conclusion: Although patients who underwent ART or non-ART treatments were more likely to have demographics that are associated with favorable neonatal outcomes, both methods of non- spontaneous twin gestations were more likely to have adverse neonatal outcomes in NICU admission and respiratory distress syndrome. The higher risk nature of pregnancies conceived through ART and fertility-enhancing drugs may necessitate closer follow ups throughout gestation to avoid adverse neonatal outcomes.