Evidence of brain injury in fetuses of mothers with preterm labor with intact membranes and preterm prelabor rupture of membranes

Abstract

Brain injury and poor neurodevelopment have consistently been reported in infants and adults born preterm. These changes occur at least in part prenatally and are associated with intra-amniotic inflammation. The pattern of brain changes has been partially documented by magnetic resonance imaging but not with neurosonography in combination with amniotic fluid brain injury biomarkers. To evaluate the prenatal features of brain remodeling and injury in fetuses from patients with preterm labor with intact membranes or preterm prelabor rupture of membranes and to investigate the potential influence of intra-amniotic inflammation as a mediator of risk. In this prospective cohort study, fetal brain remodeling and injury was evaluated by neurosonography and amniocentesis in singleton pregnant patients with preterm labor with intact membranes or preterm prelabor rupture of membranes between 24.0-34.0 weeks, with (n=41) and without (n=54) intra-amniotic inflammation. Controls for neurosonography were outpatient pregnant patients without preterm labor or preterm prelabor rupture of membranes matched 2:1 by gestational age at ultrasound. Amniotic fluid controls were patients with an amniocentesis performed for indications other than preterm labor or preterm prelabor rupture of membranes without brain or genetic defects whose amniotic fluid was collected in our biobank for research purposes matched by gestational age at amniocentesis. The group with intra-amniotic inflammation included those with intra-amniotic infection (microbial invasion of the amniotic cavity and intra-amniotic inflammation) and those with sterile inflammation. Microbial invasion of the amniotic cavity was defined as a positive amniotic fluid culture and/or positive 16S ribosomal RNA gene. Inflammation was defined by amniotic fluid interleukin-6 >13.4 ng/ml in preterm labor and >1.43 ng/ml in preterm prelabor rupture of membranes. Neurosonography included the evaluation of brain structure biometric parameters and cortical development. As amniotic fluid brain injury biomarkers we selected neuron-specific enolase, protein S100B and glial fibrillary acidic protein. Data was adjusted for cephalic biometrics, fetal growth centile, fetal sex, non-cephalic presentation and preterm prelabor rupture of membranes at admission. Fetuses from mothers with preterm labor with intact membranes or preterm prelabor rupture of membranes had signs of brain remodeling and injury. First, they had a smaller cerebellum. Thus, in intra-amniotic inflammation, non- intra-amniotic inflammation and control groups, transcerebellar diameter (median (25th; 75th percentile)) was 32.7mm (29.8; 37.6), 35.3mm (31.2;39.6) and 35.0mm (31.3;38.3), respectively (p=0.019); vermian height was 16.9 mm (15.5 ;19.6), 17.2 mm (16.0;18.9) and 17.1mm (15.7;19.0), respectively (p=0.041). Second, they presented a lower corpus callosum area (0.72mm2 (0.59;0. 81), 0.71mm2 (0.63;0.82) and 0.78mm2 (0.71;0. 91), respectively (p=0.006). Third, they showed a delayed cortical maturation (Sylvian fissure depth / biparietal diameter ratio was 0.14 (0.12;0.16), 0.14 (0.13;0.16) and 0.16 (0.15;0.17), respectively (p<0.001), and right parieto-occipital sulci depth ratio was 0.09 (0.07;0.12), 0.11 (0.09;0.14) and 0.11 (0.09;0.14), respectively (p=0.012)). Finally, regarding amniotic fluid brain injury biomarkers, fetuses from mothers with preterm labor with intact membranes or preterm prelabor rupture of membranes, had higher concentrations of neuron-specific enolase (11804.6pg/ml (6213.4;21098.8), 8397.7 pg/ml (3682.1;17398.3) and 2393.7pg/ml (1717.1;3209.3), respectively (p<0.001)); protein S100B (2030.6 pg/ml (993;4883.5), 1070.3pg/ml (365.1-1463.2) and 74.8pg/ml (44.7;93.7), respectively (p<0.001)), and glial fibrillary acidic protein (1.01ng/ml (0.54;3.88), 0.965ng/ml (0.59;2.07) and 0.24mg/ml (0.20;0.28), respectively (p=0.002)). Fetuses with preterm labor with intact membranes or preterm prelabor rupture of membranes had prenatal signs of brain remodeling and injury at the time of clinical presentation. These changes were more pronounced in those with intra-amniotic inflammation.