Noninvasive prediction models of intra-amniotic infection in women with preterm labor

Intra-amniotic infection and/or inflammation is associated with fetal cardiac concentric hypertrophy and diastolic dysfunction in preterm labor and preterm prelabor rupture of membranes

BACKGROUND

Preterm delivery is associated with cardiovascular remodeling and dysfunction in children and adults. However, it is unknown whether these effects are caused by the neonatal consequences of preterm birth or if these are already present in utero.

OBJECTIVE

We evaluated fetal cardiac morphology and function in fetuses of mothers admitted for preterm labor or preterm prelabor rupture of membranes and the association of these changes with the presence of intra-amniotic infection and/or inflammation.

STUDY DESIGN

In this prospective cohort study, fetal echocardiography and amniocentesis were performed at admission in singleton pregnant women with preterm labor and/or preterm prelabor rupture of membranes between 24.0 and 34.0 weeks' gestation with (intra-amniotic infection and/or inflammation group, n=41) and without intra-amniotic infection and/or inflammation (non-intra-amniotic infection and/or inflammation, n=54). Controls (n=48) were outpatient pregnant women without preterm labor or preterm prelabor rupture of membranes. Intra-amniotic infection was defined by a positive amniotic fluid culture or positive 16S ribosomal RNA gene. Intra-amniotic inflammation was defined by using the amniotic fluid interleukin-6 cutoff levels previously reported by our group being >1.43 ng/mL in preterm prelabor rupture of membranes and >13.4 ng/mL in preterm labor. Fetal cardiac morphology and function was evaluated using echocardiography, and troponin-I and N-terminal pro-brain natriuretic peptide concentrations were measured in amniotic fluid from women with preterm labor or preterm prelabor rupture of membranes and compared with 20 amniotic fluid Biobank samples obtained for reasons other than preterm labor or preterm prelabor rupture of membranes or cardiac pathology. The data were adjusted for the estimated fetal weight below the 10th percentile and for preterm prelabor rupture of membranes at admission and also for gestational age at amniocentesis when amniotic fluid biomarkers were compared.

RESULTS

From 2018 to 2021, 143 fetuses were included; 95 fetuses were from mothers admitted with a diagnosis of preterm labor or preterm prelabor rupture of membranes, and among those, 41 (28.7%) were in the intra-amniotic infection and/or inflammation group and 54 (37.8%) were in the non-intra-amniotic infection and/or inflammation group. A total of 48 (33.6%) fetuses were included in the control group. Fetuses with preterm labor and/or preterm prelabor rupture of membranes had signs of subclinical cardiac concentric hypertrophy (median left wall thickness of 0.93 [interquartile range, 0.72-1.16] in the intra-amniotic infection and/or inflammation group; 0.79 [0.66-0.92] in the non-intra-amniotic infection and/or inflammation group; and 0.69 [0.56-0.83] in controls; P<.001) and diastolic dysfunction (tricuspid A duration 0.23 seconds [0.21-0.25], 0.24 [0.22-0.25], and 0.21 [0.2-0.23]; P=.007). Systolic function was similar among groups. Higher values of amniotic fluid troponin I (1413 pg/mL [927-2334], 1190 [829-1636], and 841 [671-959]; P<.001) and N-terminal pro-brain natriuretic peptide were detected (35.0%, 17%, and 0%; P=.005) in fetuses with preterm labor or preterm prelabor rupture of membranes when compared with the control group. The highest N-terminal pro-brain natriuretic peptide concentrations were found in the intra-amniotic infection and/or inflammation group.

CONCLUSION

Fetuses with preterm labor or preterm prelabor rupture of membranes showed signs of cardiac remodeling and subclinical dysfunction, which were more pronounced in those exposed to intra-amniotic infection and/or inflammation. These findings support that the cardiovascular effects observed in children and adults born preterm have, at least in part, a prenatal origin.

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

BACKGROUND

Brain injury and poor neurodevelopment have been consistently reported in infants and adults born before term. 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 by neurosonography along with amniotic fluid brain injury biomarkers.

OBJECTIVE

This study aimed to evaluate the prenatal features of brain remodeling and injury in fetuses from patients with preterm labor with intact membranes or preterm premature rupture of membranes and to investigate the potential influence of intra-amniotic inflammation as a risk mediator.

STUDY DESIGN

In this prospective cohort study, fetal brain remodeling and injury were evaluated using neurosonography and amniocentesis in singleton pregnant patients with preterm labor with intact membranes or preterm premature rupture of membranes between 24.0 and 34.0 weeks of gestation, with (n=41) and without (n=54) intra-amniotic inflammation. The controls for neurosonography were outpatient pregnant patients without preterm labor or preterm premature 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 premature 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 concentrations of >13.4 ng/mL in preterm labor and >1.43 ng/mL in preterm premature rupture of membranes. Neurosonography included the evaluation of brain structure biometric parameters and cortical development. Neuron-specific enolase, protein S100B, and glial fibrillary acidic protein were selected as amniotic fluid brain injury biomarkers. Data were adjusted for cephalic biometrics, fetal growth percentile, fetal sex, noncephalic presentation, and preterm premature rupture of membranes at admission.

RESULTS

Fetuses from mothers with preterm labor with intact membranes or preterm premature rupture of membranes showed signs of brain remodeling and injury. First, they had a smaller cerebellum. Thus, in the intra-amniotic inflammation, non-intra-amniotic inflammation, and control groups, the transcerebellar diameter measurements were 32.7 mm (interquartile range, 29.8-37.6), 35.3 mm (interquartile range, 31.2-39.6), and 35.0 mm (interquartile range, 31.3-38.3), respectively (P=.019), and the vermian height measurements were 16.9 mm (interquartile range, 15.5-19.6), 17.2 mm (interquartile range, 16.0-18.9), and 17.1 mm (interquartile range, 15.7-19.0), respectively (P=.041). Second, they presented a lower corpus callosum area (0.72 mm2 [interquartile range, 0.59-0.81], 0.71 mm2 [interquartile range, 0.63-0.82], and 0.78 mm2 [interquartile range, 0.71-0.91], respectively; P=.006). Third, they showed delayed cortical maturation (the Sylvian fissure depth-to-biparietal diameter ratios were 0.14 [interquartile range, 0.12-0.16], 0.14 [interquartile range, 0.13-0.16], and 0.16 [interquartile range, 0.15-0.17], respectively [P<.001], and the right parieto-occipital sulci depth ratios were 0.09 [interquartile range, 0.07-0.12], 0.11 [interquartile range, 0.09-0.14], and 0.11 [interquartile range, 0.09-0.14], respectively [P=.012]). Finally, regarding amniotic fluid brain injury biomarkers, fetuses from mothers with preterm labor with intact membranes or preterm premature rupture of membranes had higher concentrations of neuron-specific enolase (11,804.6 pg/mL [interquartile range, 6213.4-21,098.8], 8397.7 pg/mL [interquartile range, 3682.1-17,398.3], and 2393.7 pg/mL [interquartile range, 1717.1-3209.3], respectively; P<.001), protein S100B (2030.6 pg/mL [interquartile range, 993.0-4883.5], 1070.3 pg/mL [interquartile range, 365.1-1463.2], and 74.8 pg/mL [interquartile range, 44.7-93.7], respectively; P<.001), and glial fibrillary acidic protein (1.01 ng/mL [interquartile range, 0.54-3.88], 0.965 ng/mL [interquartile range, 0.59-2.07], and 0.24 mg/mL [interquartile range, 0.20-0.28], respectively; P=.002).

CONCLUSION

Fetuses with preterm labor with intact membranes or preterm premature rupture of membranes had prenatal signs of brain remodeling and injury at the time of clinical presentation. These changes were more pronounced in fetuses with intra-amniotic inflammation.