Short-term variation of the fetal heart rate as a marker of intraamniotic infection in pregnancies with preterm prelabor rupture of membranes: a historical cohort study.

INTRODUCTION: Intraamniotic infection (IAI) and subsequent early-onset neonatal sepsis (EONS) are among the main complications associated with preterm prelabor rupture of membranes (PPROM). Currently used diagnostic tools have been shown to have poor diagnostic performance for IAI. This study aimed to investigate whether the exposure to IAI before delivery is associated with short-term variation of the fetal heart rate in pregnancies with PPROM. METHODS: Observational cohort study of 678 pregnancies with PPROM, delivering between 24 + 0 and 33 + 6 gestational weeks from 2012 to 2019 in five labor units in Stockholm County, Sweden. Electronic medical records were examined to obtain background and exposure data. For the exposure IAI, we used the later diagnosis of EONS in the offspring as a proxy. EONS is strongly associated to IAI and was considered a better proxy for IAI than the histological diagnosis of acute chorioamnionitis, since acute chorioamnionitis can be observed in the absence of both positive microbiology and biochemical markers for inflammation. Cardiotocography traces were analyzed by a computerized algorithm for short-term variation of the fetal heart rate, which was the main outcome measure. RESULTS: Twenty-seven pregnancies were categorized as having an IAI, based on the proxy diagnosis of EONS after birth. Fetuses exposed to IAI had significantly lower short-term variation values in the last cardiotocography trace before birth than fetuses who were not exposed (5.25 vs 6.62 ms; unadjusted difference: -1.37, p = 0.009). After adjustment for smoking and diabetes, this difference remained significant. IAI with a later positive blood culture in the neonate (n = 12) showed an even larger absolute difference in STV (-1.65; p = 0.034), with a relative decrease of 23.5%. CONCLUSION: In pregnancies with PPROM, fetuses exposed to IAI with EONS as a proxy have lower short-term variation of the fetal heart rate than fetuses who are not exposed. Short-term variation might be useful as adjunct surveillance in pregnancies with PPROM.

The association between undetected small-for-gestational age and abnormal admission cardiotocography: A registry-based study.

OBJECTIVE: To assess the association between undetected small-for-gestational age (SGA) fetuses and abnormal admission cardiotocography (admCTG) in a low-risk population. DESIGN: An observational study. SETTING: Four hospitals in Stockholm-Gotland, Sweden. SAMPLE: A cohort of 127 461 deliveries between 1 February 2012 and 15 June 2020. METHODS: This cohort was linked to the Swedish Neonatal Quality Register. Pregnancies were designated as high or low risk at the time of admission to the labour ward according to pre-defined risk measures. SGA was defined as a birthweight at or below the tenth centile and at or below the third centile for gestational age. MAIN OUTCOME MEASURES: The main outcome was the proportion of undetected SGA by admCTG (normal or abnormal). The secondary outcome was a composite severe adverse neonatal outcome for fetuses born less than 6 hours after admission (Apgar score <4 at 5 minutes, hypoxic-ischaemic encephalopathy grade of 2-3, neonatal seizures and neonatal death). RESULTS: The rate of abnormal admCTG was 4.9%. The proportion of SGA at or below the tenth centile was higher in the abnormal admCTG group than in the normal admCTG group, 18.6% versus 9.7% (odds ratio 2.1, 95% CI 1.9-2.3). Abnormal admCTG and SGA (≤10th) was associated with a more than 20-fold increased risk of an adverse outcome compared with normal admCTG and non-SGA (adjusted odds ratio 23.7, 95% CI 9.8-57.3). The latter had a risk of 1/2000 of an adverse outcome. CONCLUSIONS: In this low-risk population, undetected SGA fetuses were more prone to having abnormal admCTG and had a substantially higher risk of severe adverse neonatal outcomes.

Changes in perinatal management and outcomes of extremely preterm infants born below 26 weeks of gestation in a tertiary referral hospital in Sweden: Comparison between 2004-2007 and 2012-2016.

INTRODUCTION: Perinatal management of extremely preterm births in Sweden has changed toward active care from 22-23 gestational weeks during the last decades. However, considerable regional differences exist. This study evaluates how one of the largest perinatal university centers has adapted to a more active care between 2004-2007 and 2012-2016 and if this has influenced infant survival. MATERIAL AND METHODS: In this historical cohort study, women admitted with at least one live fetus and delivered at 22-25 gestational weeks (stillbirths included) at Karolinska University Hospital Solna during April 1, 2004-March 31, 2007, and January 1, 2012-December 31, 2016, were compared regarding rates of obstetric and neonatal interventions, and infant mortality and morbidity. Maternal, pregnancy and infant data from 2004-2007 were obtained from the Extreme Preterm Infants in Sweden Study while data from 2012-2016 were extracted from medical journals and quality registers. The same definitions of interventions and diagnoses were used for both study periods. RESULTS: A total of 106 women with 118 infants during 2004-2007 and 213 women with 240 infants during 2012-2016 were included. Increases between the study periods were seen regarding cesarean delivery (overall rate 14% [17/118] during 2004-2007 vs. 45% [109/240] during 2012-2016), attendance of a neonatologist at birth (62% [73/118] vs. 85% [205/240]) and surfactant treatment at birth in liveborn infants (60% [45/75] vs. 74% [157/211]). Antepartum stillbirth rate decreased (13% [15/118] vs. 5% [12/240]) and the proportion of live births increased (80% [94/118] vs. 88% [211/240]) while 1-year survival (64% [60/94] vs. 67% [142/211]) and 1-year survival without major neonatal morbidity (21% [20/94] vs. 21% [44/211]) among liveborn infants did not change between the study periods. At 22 gestational weeks, interventions rates were still low during 2012-2016, most obvious regarding antenatal steroid treatment (23%), attendance of a neonatologist (51%), and intubation at birth (24%). CONCLUSIONS: Both obstetric and neonatal interventions at births below 26 gestational weeks increased between 2004-2007 and 2012-2016 in this single center study; however, at 22 gestational weeks they were still at a low level during 2012-2016. Despite more infants being born alive, 1-year survival did not increase between the study periods.

Implementation of a revised classification for intrapartum fetal heart rate monitoring and association to birth outcome: A national cohort study.

INTRODUCTION: A revised intrapartum cardiotocography (CTG) classification was introduced in Sweden in 2017. The aims of the revision were to adapt to the international guideline published in 2015 and to adjust the classification of CTG patterns to current evidence regarding intrapartum fetal physiology. This study aimed to investigate adverse neonatal outcomes before and after implementation of the revised CTG classification. MATERIAL AND METHODS: A before-and-after design was used. Cohort I (n = 160 210) included births from June 1, 2014 through May 31, 2016 using the former CTG classification, and cohort II (n = 166 558) included births from June 1, 2018 through May 31, 2020 with the revised classification. Data were collected from the Swedish Pregnancy and Neonatal Registers. The primary outcome was moderate to severe neonatal hypoxic ischemic encephalopathy (HIE 2-3). Secondary outcomes were birth acidemia (umbilical artery pH <7.05 and base excess < -12 mmol/L or pH <7.00), A-criteria for neonatal hypothermia treatment, 5-min Apgar scores <4 and <7, neonatal seizures, meconium aspiration, neonatal mortality and delivery mode. Logistic regression was used (period II vs period I), and results are presented as adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs). RESULTS: There were no statistically significant differences in HIE 2-3 (aOR 1.27; 95% CI 0.97-1.66), proportion of neonates meeting A-criteria for hypothermia treatment (aOR 0.96; 95% CI 0.89-1.04) or neonatal mortality (aOR 0.68; 95% CI 0.39-1.18) between the cohorts. Birth acidemia (aOR 1.36; 95% CI 1.25-1.48), 5-min Apgar scores <7 (aOR 1.27; 95% CI 1.18-1.36) and <4 (aOR 1.40; 95% CI 1.17-1.66) occurred more often in cohort II. The absolute risk difference for HIE 2-3 was 0.02% (95% CI 0.00-0.04). Operative delivery (vacuum or cesarean) rates were lower in cohort II (aOR 0.82; 95% CI 0.80-0.85 and aOR 0.94; 95% CI 0.91-0.97, respectively). CONCLUSIONS: Although not statistically significant, a small increase in the incidence of HIE 2-3 after implementation of the revised CTG classification cannot be excluded. Operative deliveries were fewer but incidences of acidemia and low Apgar scores were higher in the latter cohort. This warrants further in-depth analyses before a full re-evaluation of the revised classification can be made.

Variable deceleration features and intrapartum fetal acidemia - The role of deceleration area.

OBJECTIVE: In recent years deceleration area has received increasing attention as a potential predictor of intrapartum fetal hypoxia. In several studies, the area has been manually esteemed as triangular in shape, which might introduce bias. In addition, the commonly used outcome acidemia in umbilical artery is affected by mode of delivery. We wanted to investigate the association between the variable deceleration features area, duration, depth and cumulative deceleration area (30 and 60 min) and intrapartum fetal acidemia measured as lactate concentration at fetal scalp blood sampling (FBS) in immediate connection to the decelerations. STUDY DESIGN: In the source population of 1070 labors at Karolinska University Hospital, Sweden, with FBS performed on indication, we found 507 fetuses with predominantly variable decelerations as the indication for FBS. We examined the last 60- and 30-minutes of fetal monitoring preceding the FBS with focus on deceleration area, duration and depth. The contours of the decelerations were outlined manually but the area was calculated with a computer software program. We assessed area, duration and depth both as mean values per deceleration and as cumulative values during the time period of interest. We analyzed Pearson correlations and area under receiver operating characteristics curves (AUC). We also performed an adjusted analysis, with baseline frequency, variability, and accelerations as covariates. RESULTS: Deceleration area and duration were the best predictors of intrapartum fetal acidemia (fetal lactate concentration >4.8 mmol/L measured with Lactate Pro™) with AUCs of 0.671 (0.682) and 0.678 (0.683) for cumulative measures during 30 (60) minutes prior to FBS, compared to deceleration depth with AUC of 0.632 (0.631). Corresponding Pearson correlations in 30-min (60-min) groups were 0.329 (0.335) and 0.358 (0.354) for deceleration area and duration and 0.212 (0.204) for deceleration depth. Using 250 beats cumulative cut-off for deceleration area during last 30 min, 71% vs. 43% were acidemic and non-acidemic, odds ratio = 3.2 (95% CI 1.7-6.1). CONCLUSIONS: Deceleration area and duration were better predictors of intrapartum fetal acidemia than deceleration depth. Cumulative deceleration area >250 beats during 30 min was associated with three-fold higher odds of intrapartum acidemia compared to <250 beats.

Admission cardiotocography: A hospital based validation study.

OBJECTIVE: Admission CTG is a short fetal heart rate (FHR) tracing recorded immediately at hospital admission to avoid unnecessary delay in action among pregnancies complicated by pre-existent fetal distress. There are different opinions regarding the value of the admission CTG, especially in low risk pregnancies. STUDY DESIGN: A retrospective validation study from Karolinska University Hospital, Jan 2011 to June 2015 (total number of deliveries = 40,061). All women who underwent emergency cesarean section within one hour of admittance due to suspected fetal distress were identified. We assessed whether an admission CTG was performed, if it was beneficial for the decision to perform emergent cesarean delivery and if there were objective signs of fetal compromise or if it was performed unnecessarily. The main outcome was the benefit of the admission CTG in the decision to perform emergency cesarean delivery. RESULTS: Eighty-eight cases (0.22%) fulfilled our inclusion criteria. Over 90% of these women (80/88) had objective evidence of compromised fetal well-being, i.e., indicating that emergent delivery was necessary. In 74% (54/73) of all cases was admission CTG determined to have been beneficial in the decision to perform cesarean delivery, equally effective of those classified as low- and high risk pregnancies before admission. In 28% (15/54) the CTG pathology was deemed difficult to identify by auscultation. CONCLUSION: Admission CTG was deemed beneficial in 74% of both low- and high-risk pregnancies that were delivered by emergent cesarean section within one hour of admittance due to suspected fetal distress.

Fetal heart rate short term variation during labor in relation to scalp blood lactate concentration.

INTRODUCTION: Fetal heart rate short term variation (STV) decreases with severe chronic hypoxia in the antenatal period. However, only limited research has been done on STV during labor. We have tested a novel algorithm for a valid baseline estimation and calculated STV. To explore the value of STV during labor, we compared STV with fetal scalp blood (FBS) lactate concentration, an early marker in the hypoxic process. MATERIAL AND METHODS: Software was developed which estimates baseline frequency using a novel algorithm and thereby calculates STV according to Dawes and Redman in up to four 30-minute blocks prior to each FBS. Cardiotocography traces from 1070 women in labor who had had FBS performed on 2134 occasions were analyzed. RESULTS: In acidemic cases (lactate >4.8 mmol/L; Lactate Pro™), median STV 30 minutes prior to FBS was 7.10 milliseconds compared with 6.09 milliseconds in the preacidemic (4.2-4.8 mmol/L) and 5.23 milliseconds in the normal (<4.2 mmol/L) groups (P < .05). There was a positive correlation between lactate and STV (rho = 0.16-0.24; P < .05). Median lactate concentration in cases with STV <3.0 milliseconds (n = 160) was 2.3 mmol/L. When 2 FBS were performed within 60 minutes the change rate of lactate correlated to STV (rho = 0.33; P < .001). Cases with increasing lactate concentration had a median STV of 5.29 milliseconds vs 4.41 milliseconds in those with decreasing lactate (P < .001). CONCLUSIONS: In the early stages of intrapartum hypoxia, STV increases, contrary to findings regarding chronic hypoxia in the antenatal period. The increase in the adrenergic surge is a likely explanation.

Validation of a computerized algorithm to quantify fetal heart rate deceleration area.

INTRODUCTION: Reliability in visual cardiotocography interpretation is unsatisfying, which has led to the development of computerized cardiotocography. Computerized analysis is well established for antenatal fetal surveillance but has yet not performed sufficiently during labor. We aimed to investigate the capacity of a new computerized algorithm compared with visual assessment in identifying intrapartum fetal heart rate baseline and decelerations. MATERIAL AND METHODS: In all, 312 intrapartum cardiotocography tracings with variable decelerations were analyzed by the computerized algorithm and visually examined by two observers, blinded to each other and the computer analysis. The width, depth and area of each deceleration was measured. Four cases (>100 variable decelerations) were subjected to in-depth detailed analysis. The outcome measures were bias in seconds (width), beats per minute (depth), and beats (area) between computer and observers using Bland-Altman analysis. Interobserver reliability was determined by calculating intraclass correlation and Spearman rank analysis. RESULTS: The analysis (312 cases) showed excellent intraclass correlation (0.89-0.95) and very strong Spearman correlation (0.82-0.91). The detailed analysis of >100 decelerations in four cases revealed low bias between the computer and the two observers; width 1.4 and 1.4 seconds, depth 5.1 and 0.7 beats per minute, and area 0.1 and -1.7 beats. This was comparable to the bias between the two observers: 0.3 seconds (width), 4.4 beats per minute (depth) and 1.7 beats (area). The intraclass correlation was excellent (0.90-.98). CONCLUSION: A novel computerized algorithm for intrapartum cardiotocography analysis is as accurate as gold standard visual assessment, with high correlation and low bias.

Risk factors for intrapartum acidemia - a cohort study.

PURPOSE: Birth acidemia is associated with short- and long-term morbidity in the child. Optimal intrapartum surveillance and timely interventions may reduce the incidence of these outcomes. Knowledge about conditions which increase the risks might be beneficial for optimal care. The aim with this study was to identify factors which increased the risk for lactacidemia in fetal scalp blood. MATERIALS AND METHODS: A secondary analysis of a cohort study performed at Karolinska University Hospital Stockholm Sweden between February 2009 and February 2011. The study population included 1070 women in labor where fetal scalp blood sampling (FBS) was performed. RESULTS: In a univariate logistic regression analysis for lactate >4.8 mmol/L at FBS, minor language barriers (OR 2.54; 95%CI 1.26-5.11), active bearing down (OR 2.46; 95%CI 1.12-5.39) and maternal height <155 cm (OR 2.15; 95%CI 1.08-4.26) were found as risk factors. In a multivariate logistic regression analysis, minor language barriers (OR 2.21; 95%CI 1.05-4.67) and active pushing (OR 2.68; 95%CI 1.20-6.00) remained significant. CONCLUSIONS: Language barriers, active pushing and short stature were found to be significant risk factors for intrapartum lactacidemia. In the group with minor language problems better use of interpreters might be beneficial.

Reliability in cardiotocography interpretation - impact of extended on-site education in addition to web-based learning: an observational study.

INTRODUCTION: Previous studies have shown poor reproducibility in cardiotocography (CTG) interpretation. Studies evaluating the Swedish web-based CTG-education program have not proven to increase accurate CTG assessments. The aim of this study was to evaluate whether an extended education can improve inter- and intra-observer reliability in CTG interpretation. MATERIAL AND METHODS: Six obstetricians from two different departments interpreted 106 CTG tracings on two occasions. Both departments used a Swedish national web-based CTG education and test for training. One department had, in addition, an extended education program consisting of on-site lectures and oral examinations. Inter- and intra-observer agreements were calculated by simple or weighted kappa (κ) values for the five parameters assessed on CTG. RESULTS: In both departments inter-observer and intra-observer κ showed moderate to excellent agreement (ranges for κ 0.41-0.76 and 0.65-0.93, respectively). Obstetricians at the department with extended CTG education had better inter-observer reliability for variability and accelerations. This was also the case for intra-observer reliability with the addition of baseline frequency. Both inter- and intra-observer agreement increased from moderate to substantial in both departments when decelerations were dichotomized into harmless (including early and simple variable decelerations) or hypoxic (including late, severe variable, prolonged and combined decelerations) (κ 0.63-0.78) compared with the current sub-classification of decelerations (κ 0.42-0.65). CONCLUSIONS: Agreement in CTG interpretation was better than expected in both departments, especially when divided into harmless/hypoxic changes. Combination of different learning methods (web-based, on-site lectures and case discussion) might result in a better CTG interpretation agreement compared with web-based learning solely.

Reference values for Lactate Pro 2™ in fetal blood sampling during labor: a cross-sectional study.

OBJECTIVE: Lactate Pro™ (LP1) is the only lactate meter evaluated for fetal scalp blood sampling (FBS) in intrapartum use. The reference values for this meter are: normal value <4.2 mmol/L, preacidemia 4.2-4.8 mmol/L, and acidemia >4.8 mmol/L. The production of this meter has been discontinued. An updated version, Lactate Pro 2TM (LP2), has been launched and is shown to be differently calibrated. The aims of the study were to retrieve a conversion equation to convert lactate values in FBS measured with LP2 to an estimated value if using LP1 and to define reference values for clinical management when using LP2. STUDY DESIGN: A cross-sectional study was conducted at a university hospital in Sweden. A total of 113 laboring women with fetal heart rate abnormalities on cardiotocography (CTG) had FBS carried out. Lactate concentration was measured bedside with both LP1 and LP2 from the same blood sample capillary. A linear regression model was constructed to retrieve a conversion equation to convert LP2 values to LP1 values. RESULTS: LP2 measured higher values than LP1 in all analyses. We found that 4.2 mmol/L with LP1 corresponded to 6.4 mmol/L with LP2. Likewise, 4.8 mmol/L with LP1 corresponded to 7.3 mmol/L with LP2. The correlation between the analyses was excellent (Spearman's rank correlation, r=0.97). CONCLUSION: We recommend the following guidelines when interpreting lactate concentration in FBS with LP2: <6.4 mmol/L to be interpreted as normal, 6.4-7.3 mmol/L as preacidemia indicating a follow-up FBS within 20-30 min, and >7.3 mmol/L as acidemia indicating intervention.

Absence of accelerations during labor is of little value in interpreting fetal heart rate patterns.

INTRODUCTION: The aim of this study was to investigate the correlation between increasing time since fetal heart rate (FHR) accelerations, positive (no acceleration) stimulation tests and fetal acidemia. MATERIAL AND METHODS: Observational study of FHR recordings from 1070 laboring women with indication for fetal scalp blood sampling (FBS). FHR traces were scrutinized regarding acceleration at FBS and duration since most recent acceleration. The appraiser was blinded to the FBS result. RESULTS: At the first sampling, 8.8% of fetuses had lactate concentration >4.8 mmol/L. There were no differences between those with recent accelerations (≤60 min), and absent accelerations (>60 min or never) prior to FBS (8.3% vs. 8.9%, p = 0.71). Corresponding analyses for subgroups were: fetuses with isolated absence of accelerations, 3.7% vs. 1.5% (p = 0.41), fetuses without decelerations (i.e. reduced variability and/or tachycardia), 6.1% vs. 5.1% (p = 0.81) and fetuses with serious decelerations (i.e. late or complicated variable), 15.0% vs. 16.1% (p = 0.87). Among fetuses with serious decelerations, increasing duration from most recent acceleration had a weak but statistically significant correlation to increased lactate concentration (rs = 0.12, p = 0.03). The positive likelihood ratio for acidemia with no response at FBS was 1.15. CONCLUSION: In a population with FBS performed upon indication, there was no correlation between duration since last FHR acceleration and increased lactate concentration. The majority of fetuses are not acidemic even when the FHR trace is pathological and stimulation tests are only helpful when accelerations are provoked.

Fetal heart rate monitoring of short term variation (STV): a methodological observational study.

BACKGROUND: Cardiotocography (CTG) has high sensitivity, but less specificity in detection of fetal hypoxia. There is need for adjunctive methods easy to apply during labor. Low fetal heart rate short term variation (STV) is predictive for hypoxia during the antenatal period. The objectives of our study were to methodologically evaluate monitoring of STV during labor and to compare two different monitors (Sonicaid™ and EDAN™) for antenatal use. METHODS: A prospective observational study at the obstetric department, Karolinska University hospital, Stockholm (between September 2011 and April 2015). In 100 women of ≥ 36 weeks gestation, STV values were calculated during active labor. In a subset of 20 women we compared STV values between internal and external signal acquisition. Additionally we compared antenatal monitoring with two different monitors in another 20 women. RESULTS: Median STV in 100 fetuses monitored with scalp electrode during labor (EDAN™) was 7.1 msec (range 1.3-25.9) with no difference between early (3-6 cm) and late (7-10 cm) labor (7.1 vs 6.8 msec; p = 0.80). STV calculated from scalp electrode signals were positively correlated with delta-STV (STV internal -external) (R = 0.70; p < 0.01). No significant differences were found between Sonicaid™ and EDAN™ in antenatal external monitoring of STV (median difference 0.9 msec, Spearman Rank Correlation Sonicaid vs delta-STV; R = 0.35; p = 0.14). CONCLUSIONS: Median intrapartum STV was 7.1 msec. Significant differences were found between internal and external signal acquisition, a finding that suggests further intrapartum studies to be analysed separately depending upon type of signal acquisition. Antenatal external monitoring with Sonicaid™ and EDAN™ indicates that the devices perform equally well in the identification of acidemic fetuses. Further studies are needed to assess the clinical value of intrapartum STV.

Cardiotocography patterns and risk of intrapartum fetal acidemia.

AIM: To identify cardiotocography (CTG) patterns associated with increased risk of intrapartum fetal acidemia. METHODS: A prospective observational cohort study of 1070 women with fetal scalp blood sampling (FBS) during labor was conducted at Karolinska University Hospital, Stockholm, Sweden. Women with a nonreassuring CTG pattern underwent FBS, and lactate concentration was measured at the bedside. Lactate concentrations >4.8 mmol/L were defined as fetal acidemia. A senior obstetrician, blinded to the lactate concentration at FBS, visually interpreted the CTG tracings that had prompted FBS. RESULTS: There were 2134 FBSs performed on 1070 laboring women, constituting 11% of all deliveries at this labor ward. The CTG patterns with the highest frequency of lactacidemia at FBS were late or severe variable decelerations combined with tachycardia (20%-25% at first FBS and 33%-49% at last FBS). With a normal baseline fetal heart rate, normal variability, and absence of serious decelerations, the fetal scalp blood lactate concentration at the first FBS was normal in 97.5% of cases. The group with isolated reduced variability had no increased prevalence of acidemia and median lactate concentration did not differ from the normal group. CONCLUSION: Isolated reduced variability is in most cases not a sign of hypoxia. If development of hypoxia is ruled out with one FBS, this pattern does not require monitoring with repetitive FBSs throughout labor. Late decelerations and severe variable decelerations increase the risk for intrapartum fetal metabolic acidemia to the same extent. The combination of these decelerations and tachycardia was associated with the highest rate of fetal metabolic acidemia.

Neonatal outcome and delivery mode in labors with repetitive fetal scalp blood sampling.

OBJECTIVE: To investigate if repeat (≥ 3) fetal scalp blood sampling (FBS) is associated with increased risk of caesarean delivery and worse neonatal outcome than occasional (1-2) FBS. STUDY DESIGN: Prospective cohort study of women undergoing intrapartum FBS at Karolinska University Hospital, Sweden. FBS with lactate analysis was performed if the attending doctor found the cardiotocography (CTG) tracing suspicious or abnormal. Lactate concentration was measured bedside. As a routine in all deliveries, acid-base analyses were performed on umbilical artery and vein blood immediately after delivery. Main outcome measures were metabolic acidemia in umbilical artery at delivery, Apgar score <7 at 5 min and caesarean delivery. RESULTS: During the study period there were 2134 FBSs performed on 1070 laboring women with a median of two samplings (range 1-8). There were no differences in Apgar score <7 at 5 min or metabolic acidemia in umbilical artery blood at birth between labors with 1-2 FBS and ≥ 3 FBS. Among women who underwent 1-2 FBS, 23% had a caesarean delivery as compared with 42% of those having ≥ 3 FBS. After adjustment for confounders, repeat FBS remained an independent risk factor for caesarean delivery (adj OR 2.05; 95%C.I 1.5-2.8). CONCLUSION: Fetal monitoring with repetitive FBS (≥ 3) during labors with CTG changes is safe for the baby, but the rate of caesarean delivery is doubled as compared to labors where 1-2 FBS are needed. Still, more than 50% of women with repetitive FBS will be delivered vaginally, and 1/3 of these spontaneously.

Outcome of severe intrapartum acidemia diagnosed with fetal scalp blood sampling.

AIM: To analyze short-term neonatal outcome and the sampling to delivery interval in cases with severe intrapartum acidemia diagnosed with fetal scalp blood sampling (FBS). METHODS: This is a secondary analysis of data from a trial of 2992 women, who were, when indicated, randomized to either lactate or pH analyses by FBS. Median and 95(th) centile values for lactate analyses were 2.9 mmol/L and 6.6 mmol/L, respectively. Corresponding pH values were 7.30 and 7.17. We defined severe intrapartum acidemia as lactate >6.6 mmol/L or pH <7.17. Outcome measures were cord artery pH <7.00, Apgar <7 at 5 min, hypoxic ischemic encephalopathy and time interval from FBS to delivery. RESULTS: Severe intrapartum acidemia was present in 85/1355 (6.3%) cases with lactate analyses and in 69/1008 (6.8%) cases with pH analyses. Cord artery pH <7.00 occurred in 12/154 (7.8%), Apgar <7 at 5 min in 16/154 (10.4%) and hypoxic ischemic encephalopathy in 4/154 (2.6%) of the cases. There were no differences in outcomes between the two groups. However, delivery was expedited more rapidly in the pH management group (median 16 vs. 21 min; P=0.01). CONCLUSION: Severe neonatal morbidity occurred in 10% or less in this high-risk group. FBS is an early marker of intrapartum hypoxia and can be used to prevent severe birth acidemia. Lactate might be an earlier marker than pH in the hypoxic process.

Follow-up national survey (Sweden) of routines for intrapartum fetal surveillance.

We performed a follow-up national survey concerning intrapartum fetal surveillance in Sweden to investigate if routines had changed since a previous survey in 1999, due to new data that have emerged since and technical developments. All labor wards throughout Sweden, with sizes varying from around 350 to more than 9,000 deliveries per year, have at present a rather uniform policy for intrapartum fetal surveillance with electronic fetal monitoring (EFM). They all use admission tests, fetal scalp blood sampling and have written guidelines for EFM. However, only 72% have written guidelines for fetal blood sampling. In 89% of the units lactate is analyzed in the fetal blood sampling. In half of the units the STAN-monitor is used.