Marc Jackson

Frequency of fetal heart rate categories and short-term neonatal outcome.

OBJECTIVE: To estimate the time spent in each fetal heart rate category during labor and during the last 2 hours before delivery in term singleton pregnancy and to estimate the relationship between the time spent in each category and short-term neonatal outcomes. METHODS: This study reviewed fetal heart rate data and newborn outcomes of women in term labor in 10 hospitals over 28 months. Fetal heart rate characteristics were assessed by labor and delivery nurses, and categories were assigned by computer using definitions from the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The duration of time in each category was calculated and correlated with newborn outcome. RESULTS: Forty-eight thousand four hundred forty-four patients were identified. Considering all of labor, category I was present 77.9% of the time, category II was present 22.1% of the time, and category III was present 0.004% of the time. In the last 2 hours before delivery, category I decreased to 60.9% of the duration, category II increased to 39.1%, and category III increased to 0.006%. Newborns of women whose last 2 hours were exclusively category I did well; only 0.6% had 5-minute Apgar scores less than 7, and 0.2% had low Apgar scores with neonatal intensive care unit (NICU) admission. When more than 75% of the last 2 hours was category II, low 5-minute Apgar score increased to 1.3% of patients, and low 5-minute Apgar score with NICU admission increased to 0.7% (both P<.001). CONCLUSION: Category I and category II fetal heart rate patterns are common in labor, and category III patterns are rare. Increasing time in category II in the last 2 hours of labor is associated with increased short-term newborn morbidity. LEVEL OF EVIDENCE: III

Simple, validated vaginal birth after cesarean delivery prediction model for use at the time of admission.

OBJECTIVE: To create a simple tool for predicting the likelihood of successful trial of labor after cesarean delivery (TOLAC) during the pregnancy after a primary cesarean delivery using variables available at the time of admission. METHODS: Data for all deliveries at 14 regional hospitals over an 8-year period were reviewed. Women with one cesarean delivery and one subsequent delivery were included. Variables associated with successful VBAC were identified using multivariable logistic regression. Points were assigned to these characteristics, with weighting based on the coefficients in the regression model to calculate an integer VBAC score. The VBAC score was correlated with TOLAC success rate and was externally validated in an independent cohort using a logistic regression model. RESULTS: A total of 5,445 women met inclusion criteria. Of those women, 1,170 (21.5%) underwent TOLAC. Of the women who underwent trial of labor, 938 (80%) had a successful VBAC. A VBAC score was generated based on the Bishop score (cervical examination) at the time of admission, with points added for history of vaginal birth, age younger than 35 years, absence of recurrent indication, and body mass index less than 30. Women with a VBAC score less than 10 had a likelihood of TOLAC success less than 50%. Women with a VBAC score more than 16 had a TOLAC success rate more than 85%. The model performed well in an independent cohort with an area under the curve of 0.80 (95% confidence interval 0.76–0.84). CONCLUSIONS: Prediction of TOLAC success at the time of admission is highly dependent on the initial cervical examination. This simple VBAC score can be utilized when counseling women considering TOLAC. LEVEL OF EVIDENCE: II

Cell-free DNA, inflammation, and the initiation of spontaneous term labor

BACKGROUND: Hypomethylated cell‐free DNA from senescent placental trophoblasts may be involved in the activation of the inflammatory cascade to initiate labor. OBJECTIVE: To determine the changes in cell‐free DNA concentrations, the methylation ratio, and inflammatory markers between women in labor at term vs women without labor. STUDY DESIGN: In this prospective cohort study, eligible participants carried a nonanomalous singleton fetus. Women with major medical comorbidity, preterm labor, progesterone use, aneuploidy, infectious disease, vaginal bleeding, abdominal trauma, or invasive procedures during the pregnancy were excluded. Maternal blood samples were collected at 28 weeks, 36 weeks, and at admission for delivery. Total cell‐free DNA concentration, methylation ratio, and interleukin‐6 were analyzed. The primary outcome was the difference in methylation ratio in women with labor vs without labor. Secondary outcomes included the longitudinal changes in these biomarkers corresponding to labor status. RESULTS: A total of 55 women were included; 20 presented in labor on admission and 35 presented without labor. Women in labor had significantly greater methylation ratio (P = .001) and interleukin‐6 (P < .001) on admission for delivery than women without labor. After we controlled for body mass index and maternal age, methylation ratio (adjusted relative risk, 1.38; 95% confidence interval, 1.13 to 1.68) and interleukin‐6 (adjusted relative risk, 1.12, 95% confidence interval, 1.07 to 1.17) remained greater in women presenting in labor. Total cell‐free DNA was not significantly different in women with labor compared with women without. Longitudinally, total cell‐free DNA (P < .001 in labor, P = .002 without labor) and interleukin‐6 (P < .001 in labor, P = .01 without labor) increased significantly across gestation in both groups. The methylation ratio increased significantly in women with labor from 36 weeks to delivery (P = .02). CONCLUSION: Spontaneous labor at term is associated with a greater cell‐free DNA methylation ratio and interleukin‐6 compared with nonlabored controls. As gestation advances, total cell‐free DNA concentrations and interleukin‐6 levels increase. A greater methylation ratio reflects a greater maternal contribution (vs placental) in women with labor, likely resulting from greater levels of neutrophils, lymphocytes, and uterine activation proteins at the time of labor. Although not significant, women in labor had a greater total cell‐free DNA concentration and thus could theoretically have more hypomethylated DNA available for interaction with the inflammatory cascade. Larger studies are needed to investigate this theory.

A risk stratification model to predict adverse neonatal outcome in labor

Objective:The development and evaluation of a labor risk model consisting of a combination of antepartum risk factors and intrapartum fetal heart rate (FHR) characteristics that can reliably identify those infants at risk for adverse neonatal outcome in labor.Study design:A nested case–control study of term singleton deliveries at the nine hospitals between March 2007 and December 2009. Eligibility criteria included: gestational age ⩾37.0 weeks; singleton pregnancy; documented continuous FHR monitoring for ⩾2 h before delivery; assessment of FHR tracing at least every 20 min; and, available maternal and neonatal outcomes. Adverse neonatal outcome was defined as nonanomalous infants admitted to the newborn intensive care unit with either a 5 minute Apgar score <7 or an umbilical artery pH<7.1. Initial risk score was determined using data available at 1 h after admission. Patients with an initial risk score between 7 and 15 were considered high risk. Intrapartum risk scores were then created for these patients using FHR tracing data and labor characteristics.Result:A total of 51 244 patients were identified meeting study criteria. Of the antepartum variables evaluated (n=31), 10 were associated with an adverse outcome. The high-risk group made up 28% of the population and accounted for 59.8% of the adverse outcomes. Intrapartum characteristics were then evaluated in this high-risk group. Intrapartum evaluation identified the highest risk group with a C/S rate of 40% and adverse outcome rate of 11.3%.Conclusion:Incorporation of maternal and antepartum risk factors with FHR analysis can improve the ability to identify the fetus at risk in labor.

Tocolysis for Women With Early Spontaneous Preterm Labor and Advanced Cervical Dilation

OBJECTIVE: To characterize tocolytic use and examine perinatal outcomes among women presenting very preterm with spontaneous labor and cervical dilation 4 cm or greater. METHODS: This was a retrospective cohort study. Data from January 2000 to June 2011 in a single health care system were reviewed. Women with singleton, nonanomalous fetuses and preterm labor with intact membranes between 23 and 32 weeks of gestation who had cervical dilation 4 cm or greater and less than 8 cm at admission were included. Women receiving one or more tocolytics (magnesium sulfate, indomethacin, or nifedipine) were compared with those who did not receive tocolysis. The primary outcome was composite major neonatal morbidity. RESULTS: Two hundred ninety-seven women were included; 233 (78.5%) received at least one tocolytic. Women receiving tocolysis were slightly less dilated (median 5 compared with 6 cm, P<.001) at presentation and were more likely to receive at least a partial course of corticosteroids (88.4% compared with 56.3%, P<.001). Initial composite severe neonatal morbidity rates were similar (41.6% compared with 43.8%, P=.761) regardless of tocolytic administration. Those receiving tocolysis were significantly more likely to be pregnant at least 48 hours after admission (23.6% compared with 7.8%, P=.005), but a similar proportion delivered within 7 days of admission (94.8% compared with 95.3%, P>.99), and delivery gestational ages were similar (28.9 compared with 29.2 weeks, P=.408). The incidence of chorioamnionitis and postpartum endometritis was similar between groups. CONCLUSION: The majority of women presenting very preterm with advanced cervical dilation received tocolysis. Although tocolysis administration increased the likelihood of achieving at least 48 hours of latency, initial neonatal outcomes were similar. LEVEL OF EVIDENCE: II