Fetal heart rate parameters and perinatal outcomes in fetuses with nuchal cords

BMI modifies the effect of pregnancy complications on risk of small- or large-for-gestational-age newborns

BACKGROUND

Maternal physical condition (reflected by maternal body mass index (BMI) at delivery) and pregnancy complications influence neonatal health outcomes. High BMI during pregnancy increases various health problems' risks, but studies about the synthesized effect of these factors on fetal growth, are scarce.

METHODS

The retrospective cohort study was conducted in Zhejiang Province, China from 1 January 2019 to 31 December 2021. The associations between complications and small-for-gestational-age (SGA) and large-for-gestational-age (LGA) were measured by the Fine-Gray model and subgroup analysis. Effect modification and interaction analyses were conducted to explore BMI's modification effect and complications' interaction.

RESULTS

Several complications increased the risk for SGA and LGA, some significance varied in different subgroups. There was a positive effect modification of gestational diabetes mellitus (GDM) across BMI strata on LGA (relative excess risk due to interaction (RERI) [95% CI] = 0.57 [0.09,1.04]). Several pairwise complications' interactions were synergistic (e.g., pregestational diabetes and intraamniotic infection for SGA (ratio of ORs [95% CI] = 8.50 [1.74,41.37]), pregestational diabetes and assisted reproductive technology (ART) for LGA (ratio of ORs [95% CI] = 2.71 [1.11,6.62])), one was antagonistic (placental problems and ART for LGA (ratio of ORs [95% CI] = 0.58 [0.35,0.96])).

CONCLUSIONS

High-BMI positively modified the risk of GDM on LGA. Many interactions existed when two specific pregnancy complications occurred simultaneously.

IMPACT

This is the largest retrospective study covering more than 10 pregnancy complications to date in this aspect. High-BMI (BMI > 28 kg/m2) positively modifies the risk of GDM on LGA. Many pregnancy complications influence the risk of SGA and LGA, with several interactions that may create a "syndrome" effect. Pregnant women with different BMIs should consider the additional risks caused by pregnancy complications for their heterogeneous effects on abnormal fetal growth. Measures should be taken to prevent the occurrence of other exposure factors in the "syndrome". This study may aid in developing a new strategy for improving neonatal outcomes.

Caesarean delivery of a breech singleton with eight loops of nuchal cord

Nuchal cord accidents comprise a third of stillbirths in the third trimester. These are often due to higher order nuchal cords, with more than three loops. In this report, we discuss a case of a gestation complicated by a nuchal cord with eight loops and severe fetal growth restriction, requiring expedited delivery due to non-reassuring fetal heart tones. Our case demonstrates the value of high-quality ultrasound in detecting complex nuchal cords, as well as highlighting the potentially dynamic and unstable fetal status in an affected gestation. Antenatal knowledge of nuchal cord in the setting of non-reassuring fetal status can help guide patient counselling and assist with identifying possible aetiologies. Finally, our case demonstrates that close monitoring and early intervention can prevent potentially catastrophic outcomes.

Current Perspectives of Prenatal Sonographic Diagnosis and Clinical Management Challenges of Complex Umbilical Cord Entanglement

Diagnosis of potential umbilical cord compromise, namely, true knots of the umbilical cord and nuchal cords has been enabled with increasing accuracy with current enhanced prenatal sonography. Often an incidental finding at delivery, the incidence of true knots of the umbilical cord has been estimated at between 0.04% and 3% of deliveries. This condition has been reported to account for a 4 to 10-fold increase of stillbirth and perinatal morbidity of 11% of cases. Nuchal cords, commonly observed at the delivery of uncompromised, non-hypoxic non-acidotic newborns occur more frequently with single nuchal cords noted in between 20% and 35% of all deliveries at term. Multiple nuchal cords are considerably less frequent, with decreasing frequencies inverse to the number of nuchal cord loops. While clearly single (and likely double) nuchal cords are almost uniformly associated with favorable neonatal outcomes, emerging data suggest that cases of ≥3 loops of nuchal cords are more likely to be associated with an increased risk of adverse perinatal outcome (either stillbirth or compromised neonatal condition at delivery). We define cases of a true knot of the umbilical cord, cases of ≥3 loops of nuchal cords, any combination of a true knot and nuchal cord, or any umbilical cord entanglement (nuchal or true knot) in the presence of a single umbilical artery, in singleton gestations as complex umbilical cord entanglement. Two concurrent developments, the increase in accuracy of prenatal sonographic diagnosis of complex umbilical cord entanglement and recent data confirming fatal compromise of the umbilical circulation in approximately 20% of cases of stillbirth, suggest that establishing governing body guidelines for reporting of potential umbilical cord compromise, and recommendation of consideration for early-term delivery of select cases, may be warranted. This commentary will address current perspectives of prenatal diagnosis and clinical management challenges of complex umbilical cord entanglement.

Current Perspectives of Prenatal Sonographic Diagnosis and Clinical Management Challenges of Nuchal Cord(s)

Umbilical cord accidents preceding labor are uncommon. In contrast, nuchal cords are a very common finding at delivery, with reported incidences of a single nuchal cord of approximately between 20% and 35% of all singleton deliveries at term. Multiple loops occur less frequently, with reported incidence rates inverse to the number of nuchal cords involved. Rare cases of up to 10 loops of nuchal cord have been reported. While true knots of the umbilical cord have been associated with a 4–10-fold increased risk of stillbirth, nuchal cord(s) are most often noted at delivery of non-hypoxic non-acidotic newborns, without any evidence of subsequent adverse neonatal outcome. Prior to ultrasound, nuchal cords were suspected clinically following subtle (spontaneous or evoked) electronic fetal heart rate changes. Prenatal sonographic diagnosis, initially limited to real-time gray-scale ultrasound, currently entails additional sonographic modalities, including color Doppler, power Doppler, and three-dimensional sonography, which have enabled increasingly more accurate prenatal sonographic diagnoses of nuchal cord(s). In contrast to true knots of the umbilical cord (which are often missed at sonography, reflecting the inability to visualize the entire umbilical cord, and hence are often incidental findings at delivery), nuchal cord(s), reflecting their well-defined and sonographically accessible anatomical location (the fetal neck), lend themselves with relative ease to prenatal sonographic diagnosis, with increasingly high sensitivity and specificity rates. While current literature supports that single (and possibly double) nuchal cords are not associated with increased adverse perinatal outcome, emerging literature suggests that cases of ≥3 loops of nuchal cords or in the presence of a coexisting true knot of the umbilicus may be associated with an increased risk of stillbirth or compromised neonatal status at delivery. This commentary will address current perspectives of prenatal sonographic diagnosis and clinical management challenges associated with nuchal cord(s) in singleton pregnancies.

Current Perspectives of Prenatal Sonographic Diagnosis and Clinical Management Challenges of True Knot of the Umbilical Cord

Umbilical cord accidents preceding labor are rare. Single and multiple nuchal cords, and true knot(s) of the umbilical cord, are often incidental findings noted at delivery of non-hypoxic non-acidotic newborns without any evidence of subsequent adverse neonatal outcome. In contrast to single nuchal cords, true knots of the umbilical cord, which occur in between 0.04% and 3% of all deliveries, have been associated with a reported 4 to 10 fold increased risk of stillbirth. First reported with real-time ultrasound, current widespread application of color Doppler, power Doppler and three-dimension sonography, has enabled increasingly more accurate prenatal sonographic diagnoses of true knot(s) of the umbilical cord. Reflecting the inability to visualize the entire umbilical cord at prenatal ultrasound assessment, despite detailed second and third-trimester scanning, many occurrences of incidental true knot of the umbilical cord remain undetected and are noted only at delivery. Although prenatal sonographic diagnostic accuracy is increasing, false positive sonographic diagnosis of true knot of the umbilical cord cannot be ruled out with certainty, and must continue to be considered clinically. Notwithstanding the inability to diagnose all true knots, currently there is a clear absence of clinical management guidelines by governing bodies regarding patients in whom prenatal sonographic diagnosis of true knot(s) of the umbilical cord is / are suspected. As a result, in many prenatal ultrasound units, suspected sonographic findings suggestive of or consistent with true knot of the umbilical cord are often disregarded, not documented, and patients are not uniformly informed of this potentially life-threatening condition, which carries an associated considerable risk of stillbirth. This commentary will address current perspectives of prenatal sonographic diagnostic and management challenges associated with true knot(s) of the umbilical cord in singleton pregnancies.

Electronic Fetal Monitoring and Neonatal Outcomes when a Nuchal Cord Is Present at Delivery

OBJECTIVE

This study aimed to determine the association between nuchal cord, electronic fetal monitoring parameters, and adverse neonatal outcomes.

STUDY DESIGN

This was a prospective cohort study of 8,580 singleton pregnancies. Electronic fetal monitoring was interpreted, and patients with a nuchal cord at delivery were compared with those without. The primary outcome was a composite neonatal morbidity index. Logistic regression was used to adjust for confounders.

RESULT

Of 8,580 patients, 2,071 (24.14%) had a nuchal cord. There was no difference in the risk of neonatal composite morbidity in patients with or without a nuchal cord (8.69 vs. 8.86%; p = 0.81). Nuchal cord was associated with category II fetal heart tracing and operative vaginal delivery (OVD) (6.4 vs. 4.3%; p < 0.01).

CONCLUSION

Nuchal cord is associated with category II electronic fetal monitoring parameters, which may drive increased rates of OVD. However, there is no significant association with neonatal morbidity.

Nuchal cord at delivery and perinatal outcomes: Single-center retrospective study, with emphasis on fetal acid-base balance

AIM

Our study objectives were to evaluate umbilical cord blood acid-base balance in presence of nuchal cord at delivery, effects of nuchal cord at delivery on perinatal outcomes and incidence of nuchal cord in a racially diverse population.

METHODS

Perinatal records of 2530 women (predominantly African American and Hispanic) who delivered in 2012 were examined. Perinatal outcomes of women who delivered a baby with nuchal cord were compared with those without nuchal cord.

RESULTS

In this study, incidence of nuchal cord was 23.5% and incidence of tight nuchal cord was 1.9%; 4.2% of babies with nuchal cord required resuscitation and 3.2% of babies with nuchal cord needed to be admitted to NICU. In our study, 4.2% of babies with nuchal cord required resuscitation and in total 3.2% of babies with nuchal cord needed to be admitted to NICU. Nuchal cord frequency increased from 15.6% at ≤36 weeks to 22.8% at ≥37 weeks. Significantly elevated umbilical cord Veno-Arterial pH differential was noted in babies with nuchal cord, indicating fetal acidemia.

CONCLUSIONS

Perinatal outcomes of pregnancies with nuchal cord in predominantly African American and Hispanic women were not adversely affected. Analysis of umbilical cord blood gases suggests mixed respiratory and metabolic fetal acidosis.

Is nuchal cord justified as a cause of obstetrician anxiety?

PURPOSE

Birth asphyxia leading to acidosis comprises 20-60 % of perinatal mortality. Nuchal cord (NC) is one of the possible causes of birth asphyxia. Majority of fetuses who are antenatally detected to have nuchal cord are able to achieve successful vaginal birth. The purpose of this study was to analyze the effect of nuchal cord on fetal acid base status and perinatal outcome in vaginal deliveries.

STUDY DESIGN

150 parturients were equally divided into three groups after vaginal delivery based on no NC, single and multiple loops. Umbilical cord arterial blood was analyzed for biochemical markers i.e. pH, PO2, SPO2, PCO2, HCO3 (-), standard base excess and lactate for acidosis. Labor complications like abnormal FHR, meconium-stained liquor, prolonged second stage, instrumental vaginal delivery, third stage complications were compared. In neonates, birth weight, Apgar score ≤7 at 5 min, NICU admission and other morbidity and mortality during hospital stay were compared among groups using suitable statistical tests. Above parameters were also compared between tight and loose loops.

RESULT

Nuchal cord groups had significantly higher frequency of labor complications than no NC group, especially tight loops. Neonates with NC had significantly higher frequency of meconium-stained liquor, Apgar score ≤7 at 5 min, deranged biochemical markers, NICU transfer. However, none of the neonate had pH in acidosis range and majority were discharged in healthy condition.

CONCLUSION

Patients with NC are likely to have uneventful labor and delivery as cord compression is transient and most fetuses are able to compensate for reduce umbilical blood flow. Routine antenatal ultrasound scan is not advisable, as mode of delivery and labor management does not change with detection of NC antenatally. Therefore, vaginal delivery with routine labor protocol can be allowed in cases of nuchal cord.