Fetal Heart Rate Characteristics Research Articles

Machine Learning Prediction of Fetal Health Status from Cardiotocography Examination in Developing Healthcare Contexts

Reducing neonatal mortality is a critical global health objective, especially in resource-constrained developing countries. This study employs machine learning (ML) techniques to predict fetal health status based on cardiotocography (CTG) examination findings, utilizing a dataset from the Kaggle repository due to the limited comprehensive healthcare data available in developing nations. Features such as baseline fetal heart rate, uterine contractions, and waveform characteristics were extracted using the RFE wrapper feature engineering technique and scaled with a standard scaler. Six ML models—Logistic Regression (LR), Decision Tree (DT), Random Forest (RF), Gradient Boosting (GB), Categorical Boosting (CB), and Extended Gradient Boosting (XGB)—are trained via cross-validation and evaluated using performance metrics. The developed models were trained via cross-validation and evaluated using ML performance metrics. Eight out of the 21 features selected by GB returned their maximum Matthews Correlation Coefficient (MCC) score of 0.6255, while CB, with 20 of the 21 features, returned the maximum and highest MCC score of 0.6321. The study demonstrated the ability of ML models to predict fetal health conditions from CTG exam results, facilitating early identification of high-risk pregnancies and enabling prompt treatment to prevent severe neonatal outcomes.

Analysis of the maternal and fetal adverse outcomes of 154 pregnant women with cesarean section in the second stage of labor

Objective: To investigate the perinatal maternal and fetal adverse outcomes of cesarean section in the different duration of the second stage of labor. Methods: A retrospective cohort study was conducted on the clinical data of 154 pregnant women with singleton head pregnancy who underwent cesarean section at different times of the second stage of labor due to maternal and fetal factors in the First Affiliated Hospital of Nanjing Medical University from January 1, 2019 to December 31, 2021. According to the duration of the second stage of labor, they were divided into <2 h group (54 cases), 2-<3 h group (61 cases), and ≥3 h group (39 cases). The general data of pregnant women and neonates, preoperative maternal and neonatal conditions related to labor stages, surgical indications, surgical procedures, and perioperative maternal and neonatal adverse outcomes were compared among the three groups. Results: (1) General Information: there were no significant differences in maternal age, gravidity and parity, proportion of primipara, gestational age at delivery, body mass index before delivery, pregnancy complications, labor analgesia rate and the duration of the first stage of labor among the three groups (all P>0.05). The differences of the gender composition, birth weight and incidence of macrosomia of the three groups were also not statistically significant (all P>0.05). (2) Maternal and fetal status and surgical indications: the incidence of intrapartum fever and type Ⅱ and Ⅲ fetal heart rate monitoring in the <2 h group were higher than those in the 2-<3 h group and the ≥3 h group, and the preoperative fetal head position in the ≥3 h group was lower than that in the 2-<3 h group, with statistically significant differences (all P<0.05). The proportion of cesarean section due to "fetal distress" was 40.7% (22/54) in the <2 h group, which was higher than that in the 2-<3 h group (4.9%, 3/61) and the ≥3 h group (2.6%, 1/39). The proportions of surgical indication of "relative cephalo-pelvic disproportion" were 98.4% (60/61) and 94.9% (37/39) in the 2-<3 h group and ≥3 h group, respectively, and the surgical indication of "fetal head descent arrest" were 41.0% (25/61) and 59.0% (23/39), respectively. Compared with <2 h group [63.0% (34/54), 13.0% (7/54)], the differences were statistically significant (all P<0.05). There were no significant difference in surgical indications between 2-<3 h group and ≥3 h group (all P>0.05). (3) Intraoperative conditions and perioperative complications of cesarean section: the puerperal morbidity rate of <2 h group was 37.0% (20/54), which was higher than those of 2-<3 h group (18.0%, 11/61) and ≥3 h group (7.7%, 3/39), the difference was statistically significant (P<0.05). There were no significant differences in operation time, intraoperative blood loss, incidence of fetal head inlay, uterine incision tear, modified B-Lynch suture for uterine atony, postpartum hemorrhage, perioperative blood transfusion, preoperative hemoglobin (Hb) level, perioperative Hb change, and postoperative hospital stay among the three groups (all P>0.05). (4) Adverse neonatal outcomes: non-hemolytic neonatal hyperbilirubinemia in ≥3 h group was 35.9% (14/39), which was significantly higher than that in <2 h group (13.0%, 7/54; P<0.05). Among the neonates admitted to neonatal intensive care unit (NICU) within 1 week after birth, the proportion of neonates admitted to NICU due to neonatal hyperbilirubinemia in ≥3 h group (15/19) was significantly higher than that in <2 h group (9/17) and 2-<3 h group (10/19), and the differences were statistically significant (all P<0.05). However, there was no significant difference between the <2 h group and the 2-<3 h group (P>0.05). There was no perinatal death in the three groups. Conclusions: The rate of puerperal morbidity is higher in patients who were transferred to cesarean section within 2 hours of the second stage of labor. In the early stage of the second stage of labor, the monitoring of fetal heart rate and amniotic fluid characteristics should be strengthened, especially the presence or absence of prenatal fever. In good maternal and neonatal conditions, conversion to cesarean section after 2 hours of the second stage of labor does not significantly increase the incidence of serious adverse maternal and neonatal outcomes. For the second stage of labor more than 3 hours before cesarean section, it is necessary to strengthen the monitoring of neonatal bilirubin.

Computerized analysis of fetal heart rate pattern in the third trimester of low-risk pregnancy by long-range electronic fetal monitoring

Background With computerized analysis of fetal heart rate(FHR) data from long-range monitoring, we aimed to comprehensively clarify the characteristics of FHR with increasing gestational age in low-risk pregnant women during the third trimester of pregnancy. Methods This was an observational study. 85 fetuses of low-risk pregnant women were included. The data covered 28 ∼ 40 weeks of gestation, and 125 cases of FHR monitoring from 85 fetuses were totally collected. The FHR baseline rate, variability, and acceleration were computationally calculated, analyzed and compared. Results The average effective monitoring time for each case was 13.9 ± 4.3 h. FHR baseline gradually decreased as the gestational age progressed, and the maximum FHR baseline appeared at 28–29 weeks, which was 137.5 (133.0, 141.3) bpm, whereas the minimum FHR baseline appeared at 38–39 weeks, that was 132.8 (128.1, 138.4) bpm. FHR variability fluctuated in (4–12）bpm. It gradually increased from 28 to 33 weeks of gestation, reached the maximum of 7.6 (6.0–9.4) bpm, and then decreased until full-term pregnancy. The moderate variability proportion of FHR gradually increased from 28 weeks of gestation, peaked at 32–33 weeks as 65.8%, and then gradually decreased to 56.2% at 37 weeks, which was maintained at this level until 39 weeks. The variation tendency of minimal variability proportion was opposite to moderate variability proportion. When it reached 40 weeks, the minimal and moderate variability proportions were 50.0% and 49.0%, respectively. The FHR acceleration area showed no trend change during the third trimester, while fluctuated in (29.5–42.4) lattices/h. Conclusion This study revealed that the characteristics of FHR gradually changed with increasing gestational age, and the most obvious change was observed at 32–33 weeks, demonstrating that the specific gestational weeks may be an important period for the physiological bias of FHR tends to mature.

Prolonged Fetal Heart Rate Decelerations in Labor: Can We Reduce Unplanned Primary Cesarean Sections in This Group?

Non-reassuring fetal tracing is the second leading cause of primary cesarean delivery in the United States. Prolonged fetal heart rate decelerations are non-reassuring fetal heart rate characteristics, which do not uniformly predict poor fetal outcome but can prompt obstetricians to proceed with cesarean delivery. The objective of this manuscript is to identify a strategy to reduce the primary cesarean section rate in patients with prolonged fetal heart rate decelerations in labor. This is a retrospective cohort study over a 5-year period at an academic medical center, including patients undergoing primary cesarean section following labor induction, augmentation, or spontaneous labor who were noted to have prolonged fetal heart rate deceleration(s) in the 1h prior to the time of delivery. Two groups were compared: "crash" cesarean sections versus "emergent" cesarean sections. The primary outcome was if fetal heart tones were rechecked in the operating room prior to cesarean section incision. Secondary outcomes included maternal-fetal monitoring versus Doppler fetal heart tones in the operating room, return to baseline noted in the operating room, fetal outcomes, fetal monitoring characteristics, and anesthesia type between crash versus emergent groups. Of 1969 term singleton cesarean sections, 119 patients met our inclusion criteria (emergent group n = 80) (crash group n = 39), which accounted for 13.9% of all primary cesarean sections during the study period. The emergent group had a significantly higher rate of reassessment of fetal heart tones in the operating room n = 61 (76.2%) versus the crash group n = 15 (38.4%) (p ≤ 0.0001). There were no statistically significant differences regarding fetal outcomes between the two groups. The crash group had a higher rate of category 1 fetal heart rate tracing prior to the prolonged deceleration, a longer median prolonged deceleration, and a deeper median nadir of the prolonged deceleration; these differences were statistically significant. The prolonged-to-delivery interval was significantly shorter in the crash group (median = 15min) than tin he emergent group (median = 33min) (p ≤ 0.0001). The crash group also had a higher rate of general anesthesia (n = 11, 28.2%) than the emergent group (n = 6, 7.5%) (p = 0.002). The crash group was specifically investigated. Of the 15 patients with fetal heart tones rechecked in the crash group, 7 had returned to baseline in the operating room, but underwent cesarean section without fetal monitoring. Our results indicate that the practice of placing patients on fetal monitor upon arrival to the operating room prior to performing crash cesarean delivery could reduce the rate of primary cesarean deliveries performed for prolonged decelerations in labor. When fetal heart tones have returned to baseline upon arrival in the operating room, the decision to proceed with cesarean delivery can be reconsidered. However, many clinical factors must be taken into consideration, and the decision to proceed is ultimately at the discretion of the obstetrics provider.

Characteristics of fetal and maternal heart rate tracings during labor: A prospective observational study.

Fetal well-being is assured during labor and delivery with the employment of electronic fetal heart monitoring (EFHM). In uncommon instances, maternal heart rate (MHR) instead of fetal heart rate (FHR) can be the source of signals on monitors (signal ambiguity) leading to erroneous interpretation and management. Information about MHR characteristics are comparatively inadequate. We aim to analyze and compare MHR and FHR characteristics during the first and second stages of labor. A prospective cohort study was conducted in a single tertiary care center during a one year period. Fifty one healthy full term women with singleton pregnancies during labor were enrolled. Uterine contractions, MHR and FHR were recorded simultaneously during both stages of labor by monitors designed for twin gestation. When compared to FHR, MHR had significantly lower baseline rate during 1st and 2nd stages (p < 0.0001). It demonstrated also more marked beat-to-beat variability during both stages (p < 0.0001). MHR showed significantly more accelerations (p = 0.03 and p = 0.008) and less decelerations (p < 0.0001 and p = 0.021) during 1st and 2nd stages respectively. All characteristic parameters and patterns produced by FHR could be mimicked by MHR as well, though, at different frequencies. Understanding EFHM patterns suspected to be MHR artefacts and the employment of modern monitors that simultaneously obtain and display FHR and MHR can unmask ambiguity and avert related misinterpretation problems. Similar studies should be conducted in high-risk groups where the potential for fetal hypoxia/acidosis is increased.

An Evaluation of Fetal Heart Rate Characteristics Associated With Neonatal Encephalopathy: A Case-Control Study

(BJOG. 2018;125(11):1480–1487) Neonatal encephalopathy (NE) is characterized by abnormal neurological function that presents with decreased level of consciousness or seizures, difficulty maintaining respirations, and abnormal reflexes or tone. This clinical condition is identified shortly after birth with an incidence of 2 to 6/1000 live births. There is incomplete understanding of the etiology of NE and no evidence-based interventions to prevent its occurrence. The objective of the study was to identify predelivery fetal heart rate (FHR) characteristics associated with NE. The hypothesis was category III FHR tracings would be associated with NE.

Intermittent auscultation fetal monitoring during labour: A systematic scoping review to identify methods, effects, and accuracy.

BackgroundIntermittent auscultation (IA) is the technique of listening to and counting the fetal heart rate (FHR) for short periods during active labour and continuous cardiotocography (CTC) implies FHR monitoring for longer periods. Although the evidence suggests that IA is the best way to monitor healthy women at low risk of complications, there is no scientific evidence for the ideal device, timing, frequency and duration for IA. We aimed to give an overview of the field, identify and describe methods and practices for performing IA, map the evidence and accuracy for different methods of IA, and identify research gaps.MethodsWe conducted a systematic scoping review following the Joanna Briggs methodology. Medline, EMBASE, Cinahl, Maternity & Infant Care, Cochrane Library, SveMed+, Web of Science, Scopus, Lilacs and African Journals Online were searched for publications up to January 2019. We did hand searches in relevant articles and databases. Studies from all countries, international guidelines and national guidelines from Denmark, United Kingdom, United States, New Zealand, Australia, The Netherlands, Sweden, Denmark, and Norway were included. We did quality assessment of the guidelines according to the AGREEMENT tool. We performed a meta-analysis assessing the effects of IA with a Doppler device vs. Pinard device using methods described in The Cochrane Handbook, and we performed an overall assessment of the summary of evidence using the GRADE approach.ResultsThe searches generated 6408 hits of which 26 studies and 11 guidelines were included in the review. The studies described slightly different techniques for performing IA, and some did not provide detailed descriptions. Few of the studies provided details of normal and abnormal IA findings. All 11 guidelines recommended IA for low risk women, although they had slightly different recommendations on the frequency, timing, and duration for IA, and the FHR characteristics that should be observed. Four of the included studies, comprising 8436 women and their babies, were randomised controlled trials that evaluated the effect of IA with a Doppler device vs. a Pinard device. Abnormal FHRs were detected more often using the Doppler device than in those using the Pinard device (risk ratio 1.77; 95% confidence interval 1.29–2.43). There were no significant differences in any of the other maternal or neonatal outcomes. Four studies assessed the accuracy of IA findings. Normal FHR was easiest to identify correctly, whereas identifying periodic FHR patterns such as decelerations and saltatory patterns were more difficult.ConclusionAlthough IA is the recommended method, no trials have been published that evaluate protocols on how to perform it. Nor has any study assessed interrater agreements regarding interpretations of IA findings, and few have assessed to what degree clinicians can describe FHR patterns detected by IA. We found no evidence to recommend Doppler device instead of the Pinard for IA, or vice versa.

Diurnal rhythm of fetal heart rate in third trimester of pregnancy

Objective: To investigate the diurnal rhythms of fetal heart rate in third trimester of pregnancy. Methods: From June 2014 and October 2017, 97 cases of low-risk pregnancy women who received antenatal care and deliveried in Peking University Third Hospital were collected. Totally 130 cases of fetal heart rate and maternal holter monitoring data were analyzed. All cases were singleton pregnancy, cephalic position and had normal perinatal outcome. They were divided into three groups based on gestational age, 29 cases (22.3%,29/130) in pregnancy 28-33(+6) weeks, 37 cases (28.5%,37/130) in 34-36(+6) weeks, and 64 cases (49.2%, 64/130) in 37-40(+6) weeks. Fetal heart baseline (FHB) , fetal heart baseline variation (FHBV) , fetal heart rate acceleration area and maternal heart rate were acquired by computer, their diurnal rhythms and the differences among three groups were analyzed. Results: FHB、FHBV、fetal heart rate acceleration area and maternal heart rate all presented diurnal rhythms. (1) FHB rose in daytime and decreased at night with the minimum value at 2:00-5:00, and didn't decline further at night with the advancing of gestational age (P=0.548). (2) FHBV was similar to FHB, which rose in daytime and decreased at night, but declined smaller at night with the advancing of gestational age, especially after 37 weeks (P<0.01). (3) Fetal heart rate acceleration area reduced in daytime and enlarged at night, and enlarged more with the advancing of gestational age. (4) The diurnal rhythm of maternal heart rate was consistent with fetal heart rate. FHB lagged behind maternal heart rate for 1-2 hours when declining to the nocturnal nadir but been basically in sync with maternal heart rate when recovered. Conclusion: The basic characteristics of fetal heart rate in normal pregnancy exist obviously diurnal rhythms, and change in different trends with the advancing of gestational age.

An evaluation of fetal heart rate characteristics associated with neonatal encephalopathy: a case‐control study

We sought to identify fetal heart rate (FHR) characteristics that are associated with neonatal encephalopathy (NE). Retrospective case-control study. A single medical centre in Shanghai, China, 2006-2015. Women delivering a singleton, non-anomalous infant at ≥36 weeks' gestation diagnosed with NE (cases, n = 109) were compared with a group of women with unaffected infants (controls, n = 233). Two physicians blinded to the outcome independently reviewed FHR tracings during the last 30 minutes of tracing prior to delivery. FHR characteristics were compared in the two groups and multivariable logistic regression was used to adjust for confounding. Adjusted odds ratio (aOR) and 95% confidence interval (CI) for the presence of specific FHR categories and characteristics. Category II FHR tracings were observed in 89% of women prior to delivery and were not independently associated with NE. Notably, a category III FHR was observed in 17.4% of women in the NE group compared with 0.9% of women in the control group (aOR 44.99, 95% CI 7.23-279.97). Bradycardia, minimal/absent variability, late decelerations and prolonged decelerations were independently associated with NE, whereas accelerations were protective. Similar findings were found when the cases were limited to NE with arterial cord pH <7.1 and in a subgroup analysis of women with category II tracings. Category III tracings, while infrequent, are not uncommon prior to delivery among fetuses who develop NE. In contrast, most FHR tracings are category II prior to delivery; however, individual FHR characteristics within this category are associated with NE. This research was supported by the Interdisciplinary Programme of Shanghai Jiao Tong University. Category III tracings are not uncommon prior to delivery among fetuses who develop neonatal encephalopathy.

Variations from morning to afternoon of middle cerebral and umbilical artery blood flow, and fetal heart rate variability, and fetal characteristics in the normally developing fetus.

To determine if there are changes in maternal uterine blood flow, fetal brain blood flow, fetal heart rate variability, and umbilical blood flow between morning (AM) and afternoon (PM) in healthy, uncomplicated pregnancies. In this prospective study, 68 uncomplicated singleton pregnancies (mean 35 + 0.7 weeks gestation) underwent a standard observational protocol at both 08:00 (AM) and 13:30 (PM) of the same day. This protocol included Doppler measurements of uterine, umbilical, and fetal middle cerebral artery (MCA) volume flow parameters (flow, HR, peak systolic velocity [PSV], PI, and RI) followed by computerized cardiotocography. Standard descriptive statistics, χ2 and t tests were used where appropriate. P < .05 was considered significant. A significant increase in MCA flow and MCA PSV was observed in the PM compared to the AM. This was accompanied by a fall in MCA resistance. Higher umbilical artery resistance indices were also observed in the PM compared to AM. In contrast, fetal heart rate characteristics, maternal uterine artery Doppler flow and resistance indices did not vary significantly between the AM and PM. In normal pregnancies, variations in fetal cerebral and umbilical blood flow parameters were observed between AM and PM independent of other fetal movements or baseline fetal heart rate. In contrast, uterine flow parameters remained stable across the day. These findings may have implications for the use of serial Doppler parameters used to guide clinical management in high-risk pregnancies.

Association between fetal myocardial performance index and fetal heart rate monitoring: a prospective observational cohort study

Objective To evaluate whether the left myocardial performance index (MPI) changes in association with the fetal heart rate (FHR) tracing during labor. Study design Women with term, singleton pregnancies, in labor were recruited to this prospective cohort study. Primary outcome: difference in left MPI between Category of fetal heart rate tracings. Secondary outcomes: differences in left MPI by FHR characteristics. Participants underwent ultrasound examination, during which fetal MPI was measured. Results Twenty-four laboring patients were recruited. There were 13 patients with Category I FHR, 11 patients with Category II FHR, and 0 patients with Category III FHR. Demographics were similar between the groups. MPI was not significantly different between fetuses with Category I or Category II FHR (0.67 versus 0.65, p = .385). MPI was significantly higher in fetuses with accelerations versus those without (0.71 versus 0.59, p = .045). MPI was not significantly different for fetuses with or without decelerations (0.65 versus 0.68, p = .350), between deceleration type (0.50 versus 0.64 versus, 0.75, p = .421), or between variability type (0.56 versus 0.68, p = .113). Conclusions MPI of fetuses in term, laboring patients did not vary with differing FHR characteristics except for the presence or absence of accelerations.

Особливості моніторингу стану плода у вагітних з обтяженим акушерським анамнезом

The objective: to establish the features of fetus functional state definition in pregnant women with perinatal losses in history. Patients and methods. 89 pregnant women with perinatal losses in history were screened. The fetus functional status evaluation was based on cardiotocography and definition of fetal heart rate variability by cardiointervalography. Results. Received data showed the decrease of SDNN, RMSSD and pNN50 in pregnant women with perinatal losses in history, indicating the prevalence of parasympathetic effects on the fetal myocardium (p&lt;0.05). Studies of mathematical time characteristics of fetal heart rate revealed a significant overweight of the metabolic-humoral regulatory circuit in women with normal pregnancy (p&lt;0.05). Dynamic stress index evaluation indicates the centralization of heart rate regulation and significant intensity of the fetal compensatory mechanisms in pregnant women with perinatal losses in history. The cardiotocography revealed no difference between the fetal status in women of comparative groups (p&gt;0.05). Conclusions. In pregnant women with perinatal losses in history owing to autonomic nervous system disregulation a significant intensity of fetal regulatory systems and the centralization of fetal cardiac rhythm control were observed. The cardiotocography and cardiointervalography data with revealed signs of excessive sympathetic activation can serve as preclinical signs of gestational pathology. Key words: perinatal losses, fetal functional state evaluation, cardiotocography, cardiointervalography, autonomic nervous system.

678: Which fetal heart rate characteristics are associated with neonatal encephalopathy?

678: Which fetal heart rate characteristics are associated with neonatal encephalopathy?

Amnioinfusion for chorioamnionitis.

Amnioinfusion for chorioamnionitis.

Mechanism of reduction of newborn metabolic acidemia following application of a rule-based 5-category color-coded fetal heart rate management framework

sObjective: We have reported a 7-fold reduction in newborn umbilical arterial (UA) metabolic acidemia after adoption of a rule-based 5-category color-coded fetal heart rate (FHR) management framework. We sought evidence for the relationship being causal by detailed analysis of FHR characteristics and acid–base status before and after training.Methods: Rates of UA pH and base excess (BE) were determined over a 5-year period in a single Japanese hospital, serving mainly low-risk patients, with 3907 deliveries. We compared results in the 2 years before and after a 6-month training period in the FHR management system. We used a previously published classification schema, which was linked to management guidelines.Results: After the training period, there was an increase in the percentage of normal patterns (23%), and a decrease in variable decelerations (14%), late decelerations (8%) and prolonged decelerations (12%) in the last 60 min of labor compared to the pre-training period. There was also a significant reduction in mean UA pH and BE in the groups with decelerations after introduction of the FHR management framework.Conclusions: The adoption of this FHR management system was associated with a reduction of decelerations and metabolic acidemia, without a change in cesarean or vacuum delivery rates. These results suggest that the obstetrical providers were able to better select for intervention those patients destined to develop more severe acidemia, demonstrating a possible causal relationship between the management system and reduced decelerations and metabolic acidemia.

A risk stratification model to predict adverse neonatal outcome in labor

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. 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. 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%. Incorporation of maternal and antepartum risk factors with FHR analysis can improve the ability to identify the fetus at risk in labor.

Tachysystole in term labor: incidence, risk factors, outcomes, and effect on fetal heart tracings

Recent recommendations called for obstetricians to abandon the terms of "hyperstimulation" and "hypercontractility" in favor of the more rigidly defined term, "tachysystole" (TS). The aim of the current study is to describe incidence of and risk factors for TS, describe fetal heart rate (FHR) changes associated with TS, and investigate maternal and neonatal outcomes associated with TS. For this retrospective cohort study, we reviewed and analyzed the intrapartum FHR and tocometric characteristics of all patients with a singleton, nonanomalous fetus in term labor in a single hospital system over a 28-month period. Univariate association testing was done using χ(2) and t tests, comparing demographics, pregnancy characteristics, outcomes, and TS events. Multivariable association testing between risk factors and TS events were tested using generalized estimating equations, adjusting for multiple pregnancies during the study period for the same woman. There were a total of 50,335 deliveries from 48,529 women during the 28-month period. Of these, there were a total of 7567 TS events in 5363 deliveries among 5332 women. Use of oxytocin or misoprostol, an epidural, hypertension, and induction of labor were associated with an increased risk of TS. We found a doubling of TS events with any oxytocin, a dose-response correlation between oxytocin and TS, FHR changes occurring in a quarter of TS events and, finally, that presence of TS increases the chance of composite neonatal morbidity. TS is associated with specific risk factors and impacts FHR and neonatal morbidity.

Effect of Magnesium Sulfate on Fetal Heart Rate Patterns in the Second Stage of Labor

To estimate the effect of maternal exposure to magnesium sulfate on fetal heart rate characteristics during active labor. Within a 4-year retrospective cohort study of consecutive term deliveries reaching the second stage of labor, we compared women exposed to magnesium for severe preeclampsia to all women not exposed. Primary outcome was the electronic fetal monitoring tracing in the 30 minutes preceding delivery. Secondary outcomes were fetal acidemia and nursery disposition. Attributable risk estimates and multivariable logistic regression were used to estimate the association between magnesium exposure and fetal heart rate characteristics. Unadjusted risk estimates for the association between fetal heart rate characteristics and neonatal outcomes were generated stratified by group. Of 5,387 women, 248 (4.6%) were exposed to magnesium. Magnesium exposure was associated with lower fetal heart rate baseline (136.9 ± 12.3 beats per minute compared with 139.0 ± 13.5 beats per minute; P=.02), increased risk of baseline less than 120 beats per minute (adjusted odds ratio [OR] 1.76, 95% confidence interval [CI] 1.21-2.56), and increased risk of absent or minimal variability (adjusted OR 2.41, 95% CI 1.78-3.27). More than 20% increased frequency of ever absent or minimal variability was attributable to magnesium (attributable risk 0.21, 95% CI 0.15-0.27). There were no significant differences in presence or number of accelerations or decelerations; however, magnesium was associated with fewer prolonged decelerations (adjusted OR 0.64, 95% CI 0.49-0.84). After excluding women with adverse neonatal outcomes, these associations remained. Maternal exposure to magnesium is associated with lower fetal heart rate baseline within the accepted normal range, decreased variability, and fewer prolonged decelerations without evidence of adverse effect on neonatal outcome. II.

Intrapartum Fetal Heart Rate Characteristics of Nonanomalous Fetuses with Trisomy 21

To compare the intrapartum fetal heart rate (FHR) characteristics and selected birth outcomes of nonanomalous trisomy 21 (T21) fetuses to matched controls. Nonanomalous, non-growth-restricted T21 infants were identified and matched by gestational age to presumed euploid controls. We excluded women with scheduled cesarean deliveries and multiple gestations. The incidence of abnormal FHR patterns within 3 hours of delivery and birth outcomes were compared between T21 fetuses and controls. The presence of any abnormal FHR pattern was the primary outcome. Birth outcomes included 5-minute Apgar <7, neonatal intensive care unit admission, and cesarean delivery for fetal indications. Forty-four T21 infants and 44 controls were compared. Of the T21 infants, 83% were postnatally diagnosed. No significant differences were noted in the primary outcome (68% versus 59%, p = 0.37) or birth outcomes. T21 is not associated with an increased incidence of abnormal FHR patterns or adverse birth outcomes compared with presumed euploid fetuses.

Frequency of Fetal Heart Rate Categories and Short-Term Neonatal Outcome

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. 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. 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). 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. III.