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Mechanisms of Disease in Preterm Labor and Complications of Prematurity; Prenatal Diagnosis of Congenital Anomalies
- Roberto Romero, MD, Head, Program in Perinatal Research and Obstetrics
Premature birth is the leading cause of perinatal morbidity and mortality worldwide. The Perinatology Research Branch has defined preterm labor as a syndrome. One of the causes of the syndrome is an untimely decline in progesterone action, which is clinically manifested by "silent" shortening of the uterine cervix. Indeed, previous work conducted by our Branch showed that asymptomatic women who have a cervical length of 15mm or less in the second trimester of pregnancy have a 50% likelihood of delivering an early preterm neonate. Several lines of evidence suggest that the administration of vaginal progesterone to patients with a short cervix may reduce the rate of preterm birth. Last year, we reported the results of a large prospective randomized clinical trial to test this hypothesis and found that progesterone was effective in reducing the rate of preterm birth, as well as neonatal morbidity. This year, we conducted an individual patient data (IPD) meta-analysis, which included five randomized controlled trials, to evaluate, in women with a sonographic short cervix in the midtrimester, the efficacy and safety of vaginal progesterone for the prevention of preterm birth and neonatal morbidity and mortality, and also to determine whether clinical benefits were associated with the administration of vaginal progesterone in singleton and twin pregnancies. We found that treatment with vaginal progesterone substantially reduced the risk of delivery in the 27th to 34th weeks of gestation. Moreover, we concluded that progesterone treatment can reduce the rates of: (i) infant morbidity/mortality; (ii) respiratory distress syndrome; (iii) birth weights of less than 1500g, and admission to neonatal intensive care units. Based on these findings, we recommend that doctors screen pregnant patients with ultrasound of the cervix routinely at 19 to 24 weeks of gestation. It has been estimated that the routine implementation of universal screening of all pregnant women in the United States and the administration of progesterone to those with a short cervix can result in a savings of $500 million per year in the United States alone.
The Perinatology Research Branch also published a study on the effectiveness of nanodevices to deliver therapeutic agents across the blood-brain barrier using an animal model of cerebral palsy (CP). We found that newborn CP rabbits treated intravenously with a dendrimer coupled with N-acetyl-cysteine showed dramatic improvement on the first day of life, and within five days could walk and hop, while those not treated could not. The work indicates that targeted attenuation of ongoing neuroinflammation may have significant implications for the treatment of maternal intrauterine infection and inflammation-induced brain injury, which leads to disorders including cerebral palsy. This points to a new window of therapeutic opportunity for motor and cognitive deficits originating in utero and may prove useful for neuroinflammatory disorders.
Congenital anomalies continue to be a leading cause of perinatal mortality in the United States. The research agenda of the Perinatology Research Branch includes the use of three- and four-dimensional ultrasound (3DUS and 4DUS) and the development of novel approaches and algorithms aimed at facilitating the prenatal diagnosis of congenital defects, in particular, the prenatal identification of congenital heart disease, which is the leading cause of death among fetuses with congenital anomalies. This year, we compared the use of transvaginal vs. transabdominal sonography to determine the best technique to diagnose women with a short cervix. Our studies also included magnetic resonance diffusion-weighted imaging, the relationship of newborn adiposity to fetal growth based on birth weight or neonatal growth assessment score, and prospective validation of fetal weight estimation using fractional limb volume.
Individual patient meta-analysis of vaginal progesterone in women with a short cervix in the midtrimester of pregnancy
We conducted an individual patient data (IPD) meta-analysis of randomized controlled trials (RCTs) to determine whether the use of vaginal progesterone in asymptomatic women with a short cervix (less than 25 mm) in the midtrimester reduces the risk of preterm birth and improves neonatal morbidity and mortality. We also sought to determine whether clinical benefits were associated with the administration of vaginal progesterone in singleton and twin gestations. IPD meta-analyses, in which original research data for each participant in a study are sought directly from the investigators of each trial, are the gold standard for summarizing evidence across clinical studies. Five trials were included with a total of 775 women and 827 infants. Treatment with vaginal progesterone was associated with a significant (42%) reduction in the rate of preterm birth at less than 33 weeks of gestation, as well as significant reductions in the risk for preterm birth at less than 35, 34, 30, or 28 weeks of gestation. Moreover, there was a significant (43%) reduction in composite neonatal morbidity and mortality, a lower rate of neonatal intensive care unit admission and requirement for mechanical ventilation, as well as a significantly lower rate of neonates with birth weights of at less than 1500 g. There were no significant differences in adverse events between the vaginal progesterone and placebo groups. In patients with twin gestations, there was a non-significant trend toward reduction in the rate of preterm birth at at less than 33 weeks of gestation and a significant reduction in the frequency of composite neonatal morbidity/mortality. This IPD meta-analysis provides compelling evidence for the benefit of vaginal progesterone to prevent preterm birth and neonatal morbidity/mortality in women with a sonographically diagnosed short cervix. Additional randomized controlled trials are needed to allow better assessment of the efficacy of vaginal progesterone in women with both twin gestations and a short cervix.
Dendrimer-based postnatal therapy for neuroinflammation and cerebral palsy in a rabbit model
Cerebral palsy (CP) is a syndrome diagnosed as the presence of non-progressive movement disorders of developmental origins. It is a chronic condition with no effective cure. CP is commonly associated with diffuse white matter damage. There is strong evidence that neuroinflammation, caused by activated microglia and astrocytes, plays a key role in the pathogenesis of CP, particularly in preterm neonates. This year, our Program aimed to explore the effectiveness of nanodevices in delivering therapeutic agents across the blood-brain barrier, using an animal model of CP. Affected rabbits were treated intravenously with either a saline solution, the drug NAC (N-acetyl-cysteine) or a dendrimer coupled with NAC (D-NAC). Newborn rabbits with CP treated with D-NAC on the first day of life showed a dramatic improvement and, within 5 days, were able to walk and hop, while those not treated could not. Newborn CP rabbits treated with D-NAC also showed a higher neuron count and evidence of less inflammation than untreated animals. This work indicates that targeted attenuation of ongoing neuroinflammation may have significant implications for the treatment of maternal intrauterine infection and inflammation-induced brain injury, which leads to disorders such as CP. The effectiveness of postnatal D-NAC treatment points to a new window of therapeutic opportunity for conditions such as motor and cognitive deficits originating in utero. The use of dendrimers to deliver therapeutic agents also may prove useful for other neuroinflammatory disorders.
Clinical chorioamnionitis is characterized by changes in the expression of the alarmin HMGB1 and one of its receptors, sRAGE.
High mobility group box-1 (HMGB1) protein is an alarmin (a normal cell constituent released into the extracellular environment upon cellular stress/damage) capable of activating inflammation and tissue repair. The receptor for advanced glycation end products (RAGE) can bind to HMGB1. RAGE, in turn, can induce the production of pro-inflammatory cytokines; this may be modulated by soluble truncated forms of RAGE, including soluble RAGE (sRAGE) and endogenous secretory RAGE (esRAGE). We conducted a series of studies to determine whether: (i) clinical chorioamnionitis (CA) at term is associated with changes in amniotic fluid (AF) concentrations of HMGB1, sRAGE and esRAGE; and (ii) the AF concentration of HMGB1 changes with labor or as a function of gestational age. AF samples were collected from the following groups: a) mid-trimester (n=45); b) term with (n=48) and without labor (n=22) without intra-amniotic infection; and c) term with CA (n=46). We found that the median AF HMGB1 concentration was higher in patients at term with clinical CA than in those without this condition; in contrast, patients with clinical CA had a lower median sRAGE concentration than those without CA; AF concentrations of esRAGE did not significantly change in patients with clinical CA at term; and there was no significant difference in the median AF HMGB1 concentration between women at term in labor and those not in labor and between women in the mid-trimester and those at term not in labor. The findings of an increase in the AF HMGB1 concentration and a decrease in sRAGE in clinical CA at term provide evidence that an alarmin, HMGB1, and one of its receptors, sRAGE, are engaged in the process of clinical CA at term. The changes are quite different from those observed in cases of intra-amniotic infection/inflammation in preterm gestations.
Methylome of fetal and maternal monocytes and macrophages at the feto-maternal interface
The human placenta is at the epicenter of the feto-maternal interface, and maternal cells of the decidua interact directly with fetal cells, typically trophoblasts, beginning at implantation and continuing throughout pregnancy. Decidual macrophages (dM) of the mother and placental macrophages (Hofbauer cells, HC) of the fetus are deployed at the feto-maternal interface. We conducted a series of studies to characterize the DNA methylome of maternal and fetal monocytes, dM, and HC and to determine the immunobiological importance of DNA methylation in pregnancy. Paired samples were obtained from normal pregnant women at term not in labor and their neonates. Maternal monocytes (MMo) and fetal monocytes (FMo) were isolated from the peripheral blood of mothers and fetal cord blood, respectively. dM and HC were obtained from the decidua of fetal membranes and placentas, respectively. We found significant differences in DNA methylation in each comparison (MMo versus FMo, 65 loci; dM versus HC, 266 loci; MMo versus dM, 199 loci; FMo versus HC, 1030 loci); that many of the immune response–related genes were hypermethylated in fetal cells (FMo and HC) compared with maternal cells (MMo and dM); that genes encoding markers of classical macrophage activation were hypermethylated, and genes encoding alternative macrophage activation were hypomethylated in dM and HC compared with MMo and FMo, respectively; that mRNA expression of DNMT1, DNMT3A, and DNMT3B were significantly lower in dM than in HC; and that 5-azacytidine treatment increased expression of INCA1 in dM. The findings indicate that DNA methylation patterns change during monocyte-macrophage differentiation at the feto-maternal interface and suggest that DNA methylation is an important component of the biological machinery conferring an anti-inflammatory phenotype to macrophages at the feto-maternal interface.
Transabdominal evaluation of uterine cervical length during pregnancy fails to identify a substantial number of women with a short cervix.
Transabdominal evaluation of uterine cervical length during pregnancy is not adequate to identify women with a short cervix and therefore at risk for preterm delivery. While transvaginal ultrasound is considered the gold standard for the diagnosis of a short cervix during pregnancy, several investigators continue to propose that transabdominal cervical length assessment can be used to identify patients with a short cervix. To examine the value of transabdominal sonography in the identification of a sonographic short cervix, we compared reproducibility and agreement of endocervical length obtained by both methods in 220 pregnant women. Approximately 10% (n=21) of the 220 participants exhibited a cervical length of less than 25 mm by transvaginal ultrasound. Among them, only 43% (n=9) were correctly identified as having a short cervix by transabdominal ultrasound. Transvaginal ultrasound was more reproducible based on comparisons between 2D images and immediately acquired 3D volume datasets relative to transabdominal ultrasound. Therefore, we conclude that the use of transabdominal ultrasound is not appropriate to identify patients with a short cervix. Transvaginal ultrasound should be used as the primary method for measuring the endocervical canal.
Magnetic resonance diffusion-weighted imaging: reproducibility of regional apparent diffusion coefficients for the normal fetal brain
The purpose of this study was to examine the reproducibility of regional apparent diffusion coefficient (ADC) measurements of the normal brain in 50 second and third trimester (19–37 weeks) fetuses from healthy women. The secondary objective was to characterize the age-related changes in water diffusivity from various white and gray matter regions in nonsedated fetuses. Single-shot diffusion-weighted imaging (DWI) of the fetal brain was obtained using a 1.5-Tesla MR scanner and a 6-channel body array coil. ADC maps were created using 0 and 1000 b-values along three orthogonal directions. Two examiners independently measured ADC values in the cerebellar hemispheres (CH), pons, thalamus, basal ganglia (BG), centrum semiovale (CSO), frontal (FWM), parietal (PWM), temporal (TWM), and occipital white matter (OWM). Correlation between ADC values and menstrual age was assessed by linear regression. ADC values either remained constant (BG, FWM, PWM, TWM, CSO) or decreased (CH, pons, thalamus) with advancing menstrual age. Mean intra-observer bias for ADC measurements was not significantly different from zero. Small differences in inter-observer bias were detected for CH (1.260.20 vs. 1.200.18, p=0.006), PWM (1.370.29 vs. 1.330.26, p=0.02), and CSO (1.360.29 vs. 1.330.28, p<0.0001). We conclude that manually traced ADC measurements from fetal DWI are reproducible with an acceptable degree of inter-examiner variability.
The relationship of newborn adiposity to fetal growth outcome based on birth weight or the modified neonatal growth assessment score
The primary objective of this study was to develop reference ranges of neonatal adiposity using air displacement plethysmography (ADP). The reference ranges were subsequently used to compare two different methods for evaluating neonatal nutritional status. Percentage body fat (%BF) and percentage fat mass (%FM) were derived from 324 normal newborns delivered between 35–41 weeks, post-menstrual age. Results were stratified for 92 of these newborns with corresponding fetal biometry using two methods for classifying nutritional status: (i) population-based weight percentiles; and (ii) a modified neonatal growth assessment score (m3NGAS51). The m3NGAS51 is used to evaluate neonatal growth outcome on the basis of weighted growth potential realization index (GPRI) profile for weight, head circumference, mid-thigh circumference, abdominal circumference, and crown heel length. GPRI values compare the actual neonatal size measurement to predicted values using an appropriate second trimester Rossavik fetal growth model obtained from prenatal scans. At the 50th percentile, %BF varied from 7.7% (35 weeks) to 11.8% (41 weeks), while the corresponding 50th percentiles or total FM range was 186436 g. Among a subset of 92 neonates, no significant differences in adiposity were found between small for gestational age, appropriate for gestational age, and large for gestational age groups, using population-based weight standards. Classification of the same neonates using m3NGAS51 showed significant differences in mean %BF between corresponding groups. We concluded that conventional population-based weight criteria for neonatal nutritional status can lead to misclassifications on the basis of adiposity. A neonatal growth assessment score that considers the growth potential of several anatomic parameters from second trimester fetal biometry appears to more effectively classify malnourished newborns.
Prospective validation of fetal weight estimation using fractional limb volume>
Our group developed a novel fetal soft tissue parameter, fractional limb volume, for the prenatal assessment of nutritional status and for improving the precision of fetal weight estimation. The investigation prospectively evaluated the new weight prediction models over a broader range of birth weights than previously reported. Pregnant women underwent 3D ultrasonography (n=164) within four days of delivery. Birth weights ranged from 235–5,790 grams. Fetal measurements were extracted using volume data sets for biparietal diameter, abdominal circumference, femur diaphysis length, fractional arm volume, and fractional thigh volume. Fractional limb volumes were manually traced from a central portion of the humerus or femur diaphysis. Mean percentage difference (systematic error) and standard deviation of the percentage differences (random error) were calculated for estimated fetal weight (EFW). The proportion of newborns with EFW within 5% or 10% of birth weights were compared to a modified formula using model coefficients from the same local population sample. Deliveries occurred between 21.7 and 42 weeks menstrual age. Optimal model performance (1.9±6.6%) resulted from using a combination of biparietal diameter, abdominal circumference, and fractional thigh volume. The precision of this model was superior to results from using a modified model (1.1±8.4%), although accuracy of these predictions was slightly decreased for females. For all fetuses, the prediction model that incorporated fractional thigh volume correctly classified a greater proportion of EFW within 5% (55.1% versus 43.7%, p=0.03) or 10% (86.5% versus 75.9%, p<0.05) of birth weight when compared with a modified model for our local population sample. We concluded that fractional thigh volume can be added to 2D sonographic measurements of the head and trunk to improve precision of EFW. This approach supports the inclusion of soft tissue development as part of a weight estimation procedure for the assessment of generalized fetal nutritional status.
- Romero R, Nicolaides K, Conde-Agudelo A, Tabor A, O'Brien JM, Cetingoz E, Da Fonseca E, Creasy GW, Klein K, Rode L, Soma-Pillay P, Fusey S, Cam C, Alfirevic Z, Hassan SS. Vaginal progesterone in women with an asymptomatic sonographic short cervix in the midtrimester decreases preterm delivery and neonatal morbidity: a systematic review and metaanalysis of individual patient data. Am J Obstet Gynecol 2012;206:124.e1-9.
- Kannan S, Dai H, Navath RS, Balakrishnan B, Jyoti A, Janisse J, Romero R, Kannan RM. Dendrimer-based postnatal therapy for neuroinflammation and cerebral palsy in a rabbit model. Sci Transl Med 2012;4:130ra46.
- Romero R, Chaiworapongsa T, Savasan ZA, Hussein Y, Dong Z, Kusanovic JP, Kim CJ, Hassan SS. Clinical chorioamnionitis is characterized by changes in the expression of the alarmin HMGB1 and one of its receptors, sRAGE. J Matern Fetal Neonatal Med 2012;25:558-567.
- Kim SY, Romero R, Tarca AL, Bhatti G, Kim CJ, Lee J, Elsey A, Than NG, Chaiworapongsa T, Hassan SS, Kang GH, Kim JS. Methylome of fetal and maternal monocytes and macrophages at the feto-maternal interface. Am J Reprod Immunol 2012;68:8-27.
- Hernandez-Andrade E, Romero R, Ahn H, Hussein Y, Yeo L, Korzeniewski SJ, Chaiworapongsa T, Hassan SS. Transabdominal evaluation of uterine cervical length during pregnancy fails to identify a substantial number of women with a short cervix. J Matern Fetal Neonatal Med 2012;25:1682-1689.
- Tinnakorn Chaiworapongsa, MD, Wayne State University School of Medicine, Detroit, MI
- Agustin Conde-Agudelo, MD, Wayne State University School of Medicine, Detroit, MI
- Russell Deter, MD, Baylor College of Medicine, Houston, TX
- Zhong Dong, MD, PhD, Wayne State University School of Medicine, Detroit, MI
- Sorin Draghici, PhD, Wayne State University School of Medicine, Detroit, MI
- Nandor Gabor Than, MD, PhD, Wayne State University School of Medicine, Detroit, MI
- Sonia Hassan, MD, Wayne State University School of Medicine, Detroit, MI
- Edgar Hernandez-Andrade, MD, Wayne State University School of Medicine, Detroit, MI
- Rangaramanujam Kannan, PhD, Wayne State University School of Medicine, Detroit, MI
- Sujatha Kannan, MD, Wayne State University School of Medicine, Detroit, MI
- Chong-Jai Kim, MD, PhD, Wayne State University School of Medicine, Detroit, MI
- Steven J. Korzeniewski, PhD, MSc, MA, Wayne State University School of Medicine, Detroit, MI
- Wesley Lee, MD, William Beaumont Hospital, Royal Oak, MI
- Adi Tarca, PhD, Wayne State University School of Medicine, Detroit, MI
- Lami Yeo, MD, Wayne State University School of Medicine, Detroit, MI
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