Adverse neurodevelopmental outcomes higher in complicated twins

Survivors of complicated monochorionic diamniotic (MCDA) twin pregnancies (ie, complicated twins) have a higher rate of adverse neurodevelopmental outcomes compared with uncomplicated twins, suggests a study presented at RCOG 2023.

The overall prevalence of an abnormal ASQ-3* score was nearly twofold higher among complicated vs uncomplicated twins (14.5 percent vs 7.6 percent; p=0.056). Complicated twins also had significantly higher rates of impairment in the gross motor domain of the ASQ-3 compared with the control arm (8.5 percent vs 2.9 percent; p=0.031).

There were no significant differences between arms in terms of the other individual domains of the ASQ-3, including communication, fine motor, problem solving, and personal and social skills, noted Dr Smriti Prasad from St George’s Hospital, London, UK, who presented the findings at RCOG 2023.

On multivariable mixed effects regression analysis, survivors of complicated twin pregnancies had a threefold higher odds of having abnormal ASQ-3 scores in one or more domains (adjusted odds ratio, 3.28, 95 percent confidence interval, 3.27–3.29; p<0.001).

Risk factors for adverse neurodevelopmental outcomes

Among complicated twins who had more than one pathology (eg, a combination of twin-twin transfusion syndrome [TTTS] and selective foetal growth restriction [sFGR]), 32 percent had an abnormal ASQ-3 score. Whereas for those who had a single pathology, the corresponding rate was only 9 percent. A between-group comparison yielded a p value of <0.001.

Similarly, more complicated twins who have undergone prenatal intervention (eg, foetoscopic laser, bipolar cord coagulation) had an abnormal ASQ-3 score as opposed to those who did not receive any prenatal intervention (28 percent vs 2 percent; p=0.003).

“[These findings] mean that the incidence of adverse neurodevelopmental outcomes was significantly higher in complicated MCDA twins following a prenatal intervention or if there were two co-existent pathologies,” explained Prasad.

Long-term follow-up imperative

“MCDA twin pregnancies are associated with several unique complications which are a sequela of a single shared placenta with unbalanced vascular anastomosis,” said Prasad.

Over the last few decades, there has been a paradigm shift in the immediate survival and short-term outcomes of these babies, which is attributable to a clearer understanding of the pathophysiological processes and advances in foetal therapy and neonatal care, Prasad continued. “Considering these advances, there is a need to better elucidate the long-term neurodevelopmental outcomes as disability-free survival remains our goal.”

Prasad and her team prospectively investigated the incidence of adverse neurodevelopment after 1 year of age in survivors of complicated MCDA twin pregnancies compared with uncomplicated monochorionic and dichorionic twin pregnancies. Participants were divided into two groups: Cases, which comprised MCDA twin pregnancies complicated by TTTS, sFGR, or any other pathology** (n=117) and a control group, which comprised uncomplicated dichorionic diamniotic and MCDA twins (n=210).

Compared with uncomplicated twins, complicated twins had lower mean gestational age at birth (32.6 vs 35.8 weeks) and birthweight (1,742.9 vs 2,342.2 g), and higher rates of preterm birth (<32 weeks; 29 percent vs 4 percent), neonatal morbidities (49 percent vs 13 percent) and neonatal unit admission (49 percent vs 15 percent; p<0.001 for all).

Taken together, the findings are highly relevant for antenatal counseling, underscored Prasad. “Our findings reiterate the importance of long-term neurodevelopmental follow-up of these children to ensure timely optimal therapy can be initiated for those affected.”