Abstract
Objective:
To evaluate intrapartum resuscitation interventions and improvement in category II fetal heart rate (FHR) tracings.
Methods:
This secondary analysis of a randomized trial of intrapartum fetal electrocardiographic ST-segment analysis included all participants with category II FHR tracings undergoing intrauterine resuscitation: maternal oxygen, intravenous fluid bolus, amnioinfusion, or tocolytic administration. Fetal heart rate pattern-recognition software was used to confirm ccategory II FHR tracings 30 minutes prior to intervention and to analyze the subsequent 60 minutes. The primary outcome was improvement to category I within 60 minutes. Secondary outcomes included FHR tracing improvement to category I 30–60 minutes after the intervention and composite neonatal outcome.
Results:
Of 11,108 randomized participants, 2,251 (20.3%) had at least one qualifying intervention for a category II FHR tracings: 63.7% improved to category I within 60 minutes and 50.5% improved at 30–60 minutes. Only 3.4% underwent cesarean delivery and 4.1% an operative vaginal delivery for non-reassuring fetal status within 60 minutes after the intervention. Oxygen administration was the most common intervention (75.4%). Among ACOG-defined subgroups that received oxygen, the absent FHR accelerations and absent–minimal FHR variability subgroup (n=332) was more likely to convert to category I within 60 minutes than the FHR accelerations or moderate FHR variability” subgroup (n=1919), (77.0% vs. 63.0%, OR 2.0, 95%CI 1.4–2.7). The incidence of composite neonatal adverse outcome for category II tracings was 2.9% (95% CI 2.2%−3.7%) overall; 2.8% (95% CI 2.0%−3.8%) for improvement to category I within 60 minutes (n=1433); and 3.2% (95% CI 2.1%−4.6%) for no improvement within 60 minutes (n=818). However, the group with improvement had 29% lower odds for higher level neonatal care (11.8% vs. 15.9%, OR 0.71, 95%CI 0.55–0.91).
Conclusions:
Nearly two thirds of category II FHR tracings improved to category I within 60 minutes of intervention with a relatively low overall rate of the composite neonatal adverse outcome.
Funding Source:
Funded in part by Neoventa Medical.
PRECIS
The majority of category II fetal heart rate tracings improve to category I within 60 minutes of intrapartum interventions.
INTRODUCTION
Of the almost 4 million patients delivering each year in the U.S., approximately 75% undergo labor. (1) Intrauterine resuscitation is commonly attempted to improve fetal oxygenation in response to concerning fetal heart rate (FHR) tracings by improving maternal blood flow to the placenta, increasing blood oxygen content, or ameliorating umbilical cord compression. For FHR tracings characterized by absent variability and recurrent late or deep variable decelerations (NICHD Category III), there is an increased association with neonatal hypoxia and metabolic acidosis. (2) However, ccategory III tracings are relatively infrequent, occurring in about 0.09% fetuses within 30 minutes of delivery. (3) The majority of fetuses are well oxygenated, and therefore not acidotic in labor, but will have FHR changes that fall into category II, which is defined as any FHR tracing that is not category I or III. The efficacy of intrauterine resuscitation procedures to improve the fetal condition when there is a category II FHR tracing is based on limited data. (2)
Commonly performed intrauterine resuscitation techniques include maternal oxygen, intravenous hydration, tocolytic administration, and amnioinfusion. (2) Given the paucity of data, we evaluated how often these standard intrapartum resuscitation interventions lead to an improvement in category II FHR tracings within the recommended time frame of 60 minutes (4). The primary outcome was objective improvement to category I at any point in the first 60 minutes after the intervention. Secondary outcomes that were evaluated included an improvement of the FHR tracing to category I in the period between 30 and 60 minutes after the intervention to allow time for the intervention to have an effect and composite neonatal morbidity rates in the group that improved to category I compared with the group that remained category II after 60 minutes.
ROLE OF THE FUNDING SOURCE
The authors had access to relevant aggregated study data and other information (such as study protocol, analytic plan and report, validated data table, and clinical study report) required to understand and report research findings. The authors take responsibility for the presentation and publication of the research findings, have been fully involved at all stages of publication and presentation development, and are willing to take public responsibility for all aspects of the work. All individuals included as authors and contributors who made substantial intellectual contributions to the research, data analysis, and publication or presentation development are listed appropriately. The role of the sponsor in the design, execution, analysis, reporting, and funding is fully disclosed. The authors’ personal interests, financial or nonfinancial, relating to this research and its publication have been disclosed.
METHODS
We conducted a secondary analysis of data from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network STAN trial, a large, multicenter randomized controlled trial of fetal ECG ST-segment analysis used as an adjunct to conventional electronic fetal monitoring in laboring patients with singleton pregnancies >36 weeks of gestation. A total of 11,108 participants underwent randomization at 26 hospitals in the United States between 2010 and 2014. STAN methodology has been previously reported. (5) Inclusion criteria for this analysis was a participant with intrauterine resuscitation interventions of interest performed for a category II FHR tracing in either the first or second stage of labor. Participants were excluded if they had less than 60 minutes of interpretable FHR tracing post intervention, unless a decision to deliver for non-reassuring fetal status was made prior to 60 minutes. FHR pattern-recognition software (PeriCALM Patterns) was used to confirm category II FHR tracing 30 minutes prior to the intervention and to analyze the FHR tracing 60 minutes after the intervention as previously described. (6,7)
Interventions were defined as any of the following: maternal oxygen, IV fluid bolus, amnioinfusion, or tocolytic administration. If more than one intervention was performed at the same time, then each intervention was included in the analysis. If the patient had more than one episode of intervention for a category II FHR tracing, the analysis was limited to the first set of interventions for each patient. The primary outcome was improvement to category I at any point in the first 60 minutes after the intervention. Improvement of the FHR tracing to category I in the period between 30 and 60 minutes after the intervention was a secondary outcome. Secondary neonatal outcomes selected a priori were compared between groups with an improvement to category I within 60 minutes to the group without evidence of improvement and included a composite of intrapartum fetal death, neonatal death, an Apgar score of 3 or less at 5 minutes, neonatal seizure, an umbilical artery blood pH of 7.05 or less with a base deficit of 12 mmol per liter or more, intubation for ventilation at delivery, or neonatal encephalopathy (5); individual components of the composite outcome; Apgar score at 5 minutes; umbilical-artery blood gas results; and admission to the intermediate care nursery or neonatal intensive care unit.
In a post-hoc analysis, we further analyzed category II tracings according to ACOG Practice Bulletin Number 116 (Figure 1) which provides two different approaches for the management of a category II tracing. For people with category II tracings characterized by “absent FHR accelerations and absent/minimal FHR variability” delivery should be considered if there is no improvement with resuscitation efforts while those with tracings that are characterized by the presence of “FHR accelerations or moderate FHR variability” can continue surveillance and intrauterine resuscitative measures. (2) We compared these two subcategories of category II tracing for the rate of improvement to category I following each intervention, except for tocolytic administration due to its small numbers.
Figure 1:
Flow diagram of participant exclusion and inclusion. *None of the 4 interventions of interest for a Category II tracing. †No Category II tracing in 30 mins before intervention, per the PeriGen interpretation. ‡Did not have at least 60 minutes of tracing after the intervention and did not have a decision for cesarean delivery or operative vaginal delivery for nonreassuring fetal status prior to 60 minutes. STAN, fetal electrocardiographic ST-segment analysis.
Institutional review board approval was obtained from all participating centers. Categorical variables were compared with the use of the chi-square test or Fisher’s exact test, as appropriate; continuous variables with the Wilcoxon rank-sum test. Odds ratios (OR) and 95% confidence intervals were calculated. Analyses were performed using SAS 9.4. A P-value of <0.05 was chosen to denote significance. No adjustments were made for multiple comparisons. No imputation for missing data was performed.
RESULTS
Of 11,108 randomized participants, 20.3% (n= 2,251) had one or more interventions for a category II FHR tracing meeting the criteria for duration of FHR tracing pre- and post- intervention (Figure). The overall characteristics of the participants included in this analysis are shown in Table 1 and comparison with those excluded in the analysis cohort in the Table 2. Description of the labor and intervention characteristics of the cohort including the number of patients receiving more than one intervention are described in Table 3. Overall, 89.4% of interventions occurred in the first stage of labor. Eighty-three percent had one intervention, 16% had two, and 0.7% had three administered in combination. Of those with more than one intervention, 89.1% involved both oxygen administration and intravenous fluid (IVF) bolus (with or without amnioinfusion or tocolytic administration). Of the participants with an intervention for a category II FHR tracing, 63.7% improved post-intervention to category I at some point within 60 minutes and 50.5% improved to Category I between 30 and 60 minutes (Table 4). Oxygen administration was the most frequently performed intrauterine resuscitation intervention for category II FHR tracings (75.4%, n=1698), followed by IVF bolus (29.3%, n=659), amnioinfusion (10.7%, n=240) and tocolytic administration (2.0%, n=45). Improvement to category I tracing within 60 minutes was observed in the majority of participants for each intervention (range 52.1%−67.1%). (Table 4) Only 3.4% (77 participants) had a decision to undergo cesarean delivery and 4.1% (92 participants) had an operative vaginal delivery for non-reassuring fetal status within 60 minutes after the intervention. When excluding those 169 participants, cesarean delivery occurred in 30.8% (441/1433) of those that improved to category I within 60 minutes and 28.5% (185/649) that did not improve and were still at risk of cesarean delivery.
Table 1.
Characteristics of the study population (N= 2,251)
| Age, years | 27.1 ± 6.0 |
| Gestational age at time of randomization, weeks | 39.5 ± 1.2 |
| Self-identified race and ethnicity | |
| Non-Hispanic Black | 526 (23.4) |
| Non-Hispanic White | 810 (36.0) |
| Asian | 70 (3.1) |
| Hispanic | 797 (35.4) |
| Other or not recorded* | 48 (2.1) |
| Body mass index, kg/m2 | 33.5 ± 7.0 |
| Education level, years | 12.8 ± 2.5 |
| Nulliparous | 1,336 (59.4) |
| Cervical dilation at randomization, cm | 4.6 ± 1.3 |
| Induced labor | 1,363 (60.6) |
Data are n (%) or mean ± standard deviation
Other or not recorded” includes the following: Native Hawaiian or Pacific Islander, American Indian or Alaskan Native, Other (not specified), Not recorded
Table 2.
Characteristics of analyzed cohort compared to participants not included in the analysis
| Included participants (N=2,251) | Insufficient FHR tracing before intervention (N=806) |
p-value | |
|---|---|---|---|
| Age, years | 27.1 ± 6.0 | 27.4 ± 6.0 | 0.31 |
| Gestational age at time of randomization, weeks | 39.5 ± 1.2 | 39.3 ± 1.2 | 0.001 |
| Self-Identified race and ethnicity | 0.008 | ||
| Non-Hispanic Black | 23.4% | 24.8% | |
| Non-Hispanic White | 36.0% | 34.4% | |
| Asian | 3.1% | 1.6% | |
| Hispanic | 35.4% | 38.5% | |
| Other or not recorded | 2.1% | 0.7% | |
| Body mass index, kg/m2 | 33.5 ± 7.0 | 32.5 ± 6.9 | <0.001 |
| Education level, years | 12.8 ± 2.5 | 12.7 ± 2.7 | 0.29 |
| Nulliparous | 59.4% | 45.4% | <0.001 |
| Cervical dilation at randomization, cm | 4.6 ± 1.3 | 5.1 ± 1.2 | <0.001 |
| Induced labor | 60.6% | 58.4% | 0.29 |
Data are n (%) or mean ± standard deviation
Table 3.
Labor and intervention characteristics*
| Any intervention (N = 2,251) | Oxygen (N = 1,698) | IVF bolus (N = 659) | Amnioinfusion (N = 240) | Tocolysis (N = 45) | |
|---|---|---|---|---|---|
| Stage of Labor at intervention First Second |
2,012 (89.4) 239 (10.6) |
1,496 (88.1) 202 (11.9) |
602 (91.4) 57 (8.7) |
237 (98.8) 3 (1.3) |
42 (93) 3 (7) |
| Study assignment ST Analysis CTG only |
1,043 (46.3) 1,208 (53.7) |
792 (46.6) 906 (53.4) |
313 (47.5) 346 (52.5) |
117 (48.8) 123 (51.3) |
18 (40) 27 (60) |
| Given in combination with another intervention† | 376 (16.7) | 370 (21.8) | 340 (51.6) | 37 (15.4) | 20 (44) |
IVF = intravenous fluid
Data are n (%)
Note: If >1 type of intervention was performed at the same time, the case will appear in multiple columns.
Number of patients receiving more than one intervention listed in table. For specific intervention, refers to number receiving intervention in addition to another listed intervention in table.
Table 4.
Intervention characteristics and improvement of FHR tracing to Category I
| Any intervention (N = 2,251) | Oxygen (N = 1,698) | IVF bolus (N = 659) | Amnioinfusion (N = 240) | Tocolytic (N = 45) | |
|---|---|---|---|---|---|
| Improvement to Category I at any point within 60 minutes | 1,433 (63.7) | 1,105 (65.1) | 442 (67.1) | 125 (52.1) | 27 (60) |
| Improvement to Category I between 30 and 60 minutes | 1,136 (50.5) | 872 (51.4) | 357 (54.2) | 105 (43.8) | 22 (49) |
| Cesarean delivery decision within 60 minutes* | 77 (3.4) | 51 (3.0) | 26 (4.0) | 11 (4.6) | 7 (16) |
| Operative vaginal delivery within 60 minutes† | 92 (4.1) | 78 (4.6) | 29 (4.4) | 3 (1.3) | 1 (2) |
| First Stage Only | (N = 2,012) | (N = 1,496) | (N = 602) | (N = 237) | (N = 42) |
| Improvement to Category I at any point within 60 minutes | 1,362 (67.7) | 1,046 (69.9) | 425 (70.6) | 125 (52.7) | 25 (60) |
| Improvement to Category I between 30 and 60 minutes | 1,090 (54.2) | 835 (55.8) | 344 (57.1) | 105 (44.3) | 21 (50) |
| Cesarean delivery decision within 60 minutes* | 67 (3.3) | 45 (3.0) | 19 (3.2) | 11 (4.6) | 7 (17) |
| Operative vaginal delivery within 60 minutes† | 24 (1.2) | 19 (1.3) | 12 (2.0) | 2 (0.8) | 1 (2) |
| Second Stage Only | (N = 239) | (N = 202) | (N = 57) | (N = 3) | (N = 3) |
| Improvement to Category I at any point within 60 minutes | 71 (29.7) | 59 (29.2) | 17 (30) | 0 (0) | 2 (67) |
| Improvement to Category I between 30 and 60 minutes | 46 (19.3) | 37 (18.3) | 13 (23) | 0 (0) | 1 (33) |
| Cesarean delivery decision within 60 minutes* | 10 (4.2) | 6 (3.0) | 7 (12) | 0 (0) | 0 (0) |
| Operative vaginal delivery within 60 minutes† | 68 (28.5) | 59 (29.2) | 17 (30) | 1 (33) | 0 (0) |
IVF = intravenous fluid
Data are n (%)
Decision for cesarean delivery for non-reassuring fetal status made within 60 minutes of the intervention.
Vacuum- or forceps- assisted delivery for non-reassuring fetal status within 60 minutes of the intervention.
In the post-hoc analysis, of the 2,251 participants, 14.7% (n=332) were in the absent FHR accelerations and absent–minimal FHR variability subgroup; oxygen was administered in 75.9% of these cases (252/332) (Table 5). After oxygen administration, the “absent FHR accelerations and absent/minimal FHR variability” subgroup was more likely to convert to category I tracing within 60 minutes than the FHR accelerations or moderate FHR variability subgroup, (77.0% vs. 63.0%, OR 2.0, 95%CI 1.4–2.7) due to improvement in variability. After IVF bolus the “absent FHR accelerations and absent/minimal FHR variability” subgroup was also more likely to convert to a category I tracing within 60 minutes than the “FHR accelerations or moderate FHR variability subgroup”, (77% vs. 65.4%, OR 1.8, 95%CI 1.1–2.9). Amnioinfusion was not associated with a difference in conversion to a category I tracing within 60 minutes for the two category II FHR tracing subgroups.
Table 5:
Intervention characteristics and improvement of FHR tracing to Category I within 60 minutes by ACOG category II tracing type
| N | Accelerations or moderate variability* | Absent accelerations and absent/ minimal variability* | p-value | |
|---|---|---|---|---|
| Any intervention | 2,251 | 1,189/1,919 (62.0) | 244/332 (73.5) | <0.001 |
| Oxygen | 1,698 | 911/1,446 (63.0) | 194/252 (77.0) | <0.001 |
| IVF bolus | 659 | 366/560 (65.4) | 76/99 (77) | 0.03 |
| Amnioinfusion | 240 | 108/207 (52.2) | 17/33 (52) | 0.94 |
IVF = intravenous fluid
Data are proportion (%)
ACOG category II tracing type in the 30 minutes immediately before the intervention
The incidence of composite neonatal adverse outcome for category II tracing was low overall 2.9% (95% CI 2.2%−3.7%); 2.8% (95% CI 2.0%−3.8%) for those with improvement to category I within 60 minutes (n=1433) and 3.2% (95% CI 2.1%−4.6%) for those with no improvement within 60 minutes (n=818). However, compared with the group without evidence of improvement, the odds of needing higher level neonatal care (Intermediate or Intensive Care Unit) was 29% lower in the group with an improvement to category I within 60 minutes (11.8% vs. 15.9%, OR 0.71, 95%CI 0.55–0.91). The group with an improvement to category I within 60 minutes had a slightly higher umbilical cord pH than those without improvement (7.24 ± 0.06 vs. 7.23 ± 0.08, P=0.007) (Table 6).
Table 6.
Neonatal outcomes by fetal heart rate tracing category post intervention
| Outcome | Improvement to category I within 60 minutes (N=1433) | No improvement to category I within 60 minutes (N=818) | Odds Ratio (95% CI) or p-value |
|---|---|---|---|
| Composite adverse outcome | 38/1377 (2.8%) | 25/790 (3.2%) | 0.87 (0.52–1.45) |
| Intrapartum fetal death | 0 | 0 | |
| Neonatal death | 1 (0.1%) | 0 (0.0%) | |
| Apgar score ≤3 at 5 minutes | 8 (0.6%) | 5 (0.6%) | |
| Neonatal seizure | 2 (0.1%) | 1 (0.1%) | |
| Umbilical artery blood pH ≤ 7.05 | 17/1376 (1.2%) | 17/790 (2.2%) | |
| Intubation for ventilation at delivery | 19 (1.3%) | 11 (1.3%) | |
| Neonatal encephalopathy | 2 (0.1%) | 2 (0.2%) | |
| Apgar score at 5 minutes | 9 (9–9) | 9 (9–9) | P=0.24 |
| Umbilical-artery pH | 7.24 ± 0.06 | 7.23 ± 0.08 | P=0.007 |
| Intermediate care nursery or neonatal intensive care unit admission | 169 (11.8%) | 130 (15.9%) | 0.71 (0.55–0.91) |
Data are n (%), median (interquartile range), or mean ± standard deviation unless otherwise specified
Composite adverse outcome is composed of any one of the following occurrences: intrapartum fetal death, neonatal death, an Apgar score of 3 or less at 5 minutes, neonatal seizure, an umbilical artery blood pH of 7.05 or less with a base deficit of 12 mmol per liter or more, intubation for ventilation at delivery, or neonatal encephalopathy
DISCUSSION
About 20% of low-risk participants in labor at >36 weeks’ gestation underwent intervention for a category II FHR tracing, as determined by objective pattern-recognition software for FHR tracing interpretation. The majority of patients improved from category II FHR tracing to category I within 60 minutes, but 7.5% of the participants underwent either cesarean delivery or operative vaginal delivery for non-reassuring fetal status within 60 minutes after the intervention.
Maternal oxygen supplementation was the most frequently performed intrauterine resuscitation intervention (75%). We observed that after oxygen administration for a category II FHR tracing, the “absent FHR accelerations and absent/minimal FHR variability” group was more likely to convert to a category I tracing within 60 minutes than the “FHR accelerations or moderate FHR variability” group due to improvement in variability. Since we do not have a control group without oxygen administration, we are not able to determine if this improvement in the FHR tracing was due to oxygen administration itself or would have occurred even without oxygen administration. The same limitation applies to all the other interventions. Under normal physiologic conditions in sheep, the supply of oxygen to the fetus is twice the metabolic demand; thus, fetal oxygen uptake is not affected until oxygen delivery is reduced by more than half. (8) Furthermore, sheep studies suggest that when fetal hypoxia is not due to maternal hypoxia, maternal oxygen administration results in increased free radical markers in the fetus. (9) Primate research demonstrates that while maternal oxygen supplementation may correct fetal hypoxia, it will not correct acidosis. (10) In the only 3 randomized trials investigating the use of maternal oxygen supplementation in laboring patients (11–13) as well as the Cochrane Database of Systematic Reviews (14), oxygen supplementation was not demonstrated to be of benefit to the fetus. The most recent study was a non-blinded trial in which 114 participants with category II tracings were randomized to room air without a facemask vs. 10 L of oxygen per minute by non-rebreather facemask until delivery combined with additional resuscitation methods after randomization which found that room air was noninferior to maternal oxygen supplementation for the improvement of umbilical artery lactate, a marker of fetal metabolic acidosis. (13) There was no difference in resolution of recurrent decelerations within 60 minutes between the O2 (n=57) and room air groups (75.4% vs 86.0%; P=.15), but the sample size was underpowered to detect a significant difference.(15) Based on a review of the available literature, Hamel et al. (16) concluded that maternal oxygen supplementation in labor should be reserved for maternal hypoxia and is not supported by current evidence as an intervention for non-reassuring fetal status. There are currently at least three trials identified in ClinicalTrials.gov comparing supplemental oxygen to room air in participants with category II fetal heart tracings (17).
In 63% of participants receiving intravenous hydration, amnioinfusion or tocolytics as intrauterine resuscitation for a category II FHR tracing, there was an improvement of the FHR tracing to category I within 60 minutes. The underlying mechanisms for the potential benefits of these interventions are plausible. Most patients are restricted from taking oral fluids in labor and typically receive 125 mL/h of intravenous fluids, which is inadequate to maintain fluid balance during labor under typical circumstances. Adequate placenta perfusion and therefore optimal oxygenation of the fetus depend on optimal maternal intravascular volume. (18) Randomized controlled trials have demonstrated the clearest benefit of amnioinfusion for cord compression patterns most likely associated with oligohydramnios, such as those occurring early in labor or in a growth restricted or post-dates fetus. (19) Tocolysis with subcutaneous terbutaline 0.25mg was the least frequently used intervention, accounting for only 2% of the intrauterine resuscitation techniques performed. Excessive contractions, can lead to non-reassuring fetal heart patterns; use of beta-2-sympathomimetic agents may improve placental blood flow and therefore fetal oxygenation. (18)
There are numerous strengths of this study. The use of data from patients participating in the STAN trial with availability of the entire fetal heart tracing available for analysis and careful prospective collection of intrauterine interventions performed by study staff limits bias. Furthermore, the use of objective computerized FHR pattern-recognition software pre and post intervention, avoids the bias of health care professional interpretation by knowledge of an intervention being instituted to improve the FHR pattern. Additional study design strengths include the large sample size and the prospective and rigorous data collection by trained, certified study staff.
A limitation of this study is that improvement in the FHR pattern cannot be directly ascribed to the intrauterine intervention because of lack of a control group of category II tracings without intervention; the FHR pattern may have improved within 60 minutes without any intervention. However, the feasibility of having a control group without intervention for a category II tracing is unlikely given the prevailing clinical practice of intrauterine resuscitation. (2) The cohort in this analysis may not be representative of the entire population in labor given individuals who were already receiving interventions were excluded from the STAN trial. Furthermore, category II FHR tracings were considered as a single group when, in fact, there is heterogeneity in patterns which may have differing underlying mechanism and progression rates to category III tracings. Lastly, because the incidences of the composite neonatal morbidity were relatively low in the subgroups of category II tracings, this study is likely underpowered to detect a difference in this low frequency outcome.
In the majority of cases, an intervention for a category II FHR tracing was followed by an improvement in the FHR tracing to category I. The overall incidence of composite neonatal adverse outcome was relatively low for category II tracings in this study. The participants without improvement of the FHR tracing pattern after intrapartum interventions did have an increased need for higher level of neonatal care. The results of ongoing controlled trials should help us understand better the magnitude and limitations of the benefits of these widely used interventions, particularly oxygen administration.
Supplementary Material
ACKNOWLEDGMENTS:
The authors thank Ashley Salazar, RN, MSN, WHNP, for assistance with protocol development and coordination between clinical research centers; Elizabeth Thom, PhD and Michael A. Belfort, MB, BCh, MD, PhD for protocol development and oversight; and Catherine Y. Spong, MD for protocol development, oversight and outcome review.
FUNDING:
This work is supported by grants HD34208, HD53097, HD40545, HD40560, HD27869, HD40485, HD40512, HD27915, HD40544, HD40500, HD68282, HD68268, HD27917, HD21410, and U10 HD36801 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and by funding from Neoventa Medical. Comments and views expressed in this article are those of the authors and do not necessarily represent views of the National Institutes of Health. Neoventa Medical did not participate in the monitoring of the study; data collection, management, or analysis; or manuscript preparation.
Footnotes
Financial Disclosure
Alan Tita reports his institution received funds from Pfizer. Russell Miller reports money was paid to him from Janssen Research & Development, LLC, for serving on their Advisory Board service (unrelated to this manuscript topic). He also received funds from UpToDate (chapter author unrelated to this manuscript topic). David McKenna’s institution is a a satellite site for The Ohio State University for the NICHD MFMU, which pays his institution for patients enrolled in MFMU studies. Edward Chien reports that money was paid to his institution from MetroHealth. The other authors did not report any potential conflicts of interest.
Each author has confirmed compliance with the journal’s requirements for authorship.
Contributor Information
Uma M. Reddy, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD.
Steven J. Weiner, George Washington University Biostatistics Center, Washington, DC.
George R. Saade, Departments of Obstetrics and Gynecology of the University of Texas Medical Branch, Galveston, TX.
Michael W. Varner, University of Utah Health Sciences Center, Salt Lake City, UT
Sean C. Blackwell, University of Texas McGovern Medical School at UT Health, Houston, TX.
John M. Thorp, Jr., University of North Carolina at Chapel Hill, Chapel Hill, NC.
Alan T.N. Tita, University of Alabama at Birmingham, Birmingham, AL.
Russell S. Miller, Columbia University, New York, NY.
Alan M. Peaceman, Northwestern University, Chicago, IL.
David S. McKenna, The Ohio State University, Columbus, OH.
Edward K.S. Chien, MetroHealth Medical Center-Case Western Reserve University, Cleveland, OH.
Dwight J. Rouse, Brown University, Providence, RI.
Yasser Y. El-Sayed, Stanford University, Stanford, CA.
Yoram Sorokin, Wayne State University, Detroit, MI.
Steve N. Caritis, University of Pittsburgh, Pittsburgh, PA.
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