Association between sonographic measurement of fetal head circumference and labor outcome

Fetal head prior to delivery: precise measurement, using a mathematically extrapolated frontooccipital diameter

PURPOSE

To find a method that could improve the accuracy of fHC evaluation at term.

MATERIAL AND METHODS

This retrospective cohort study was based on data from the University Hospital of Zürich (USZ). Study population included singleton fetuses and newborns at term between 2015 and 2017. Fetal biometry was performed within 1 week prior to delivery. Study data consisted of two cohorts with 200 ultrasound measurements each: 200 performed by an expert, 200 by residents. fHC were compared with the newborn's head circumference (nHC). fHC was estimated using two methods: (1) fHC based on sonographically estimated frontooccipital diameter (FOD) and biparietal diameter (BPD). (2) Expected FOD was calculated as a fixed mean FOD/BPD relation, derived from biometry standards as the 50th percentile. If BPD was < 99 mm, FOD was calculated according to the formula BPD × 1.268557, If BPD was ≥ 99 mm, FOD was calculated according to the formula BPD × 1.20641443.

RESULTS

fHC was underestimated compared with nHC in the expert group: percentage error (PE =  - 3.68%, SD = 2.79), as well as in the group of residents (PE =  - 3.78%, SD = 3.20) using method 1. fHC measurement was significantly more accurate using method 2. In the expert group PE =  - 1.17%, SD = 3.08, in the group of residents PE =  - 0.95%, SD = 3.33. Bland-Altman analysis showed limits of agreement (LOA) between - 2.41338 and 0.5537828 cm for fHC.

CONCLUSIONS

Accuracy of fHC estimation could be improved by extrapolation of FOD when real-time FOD cannot be measured.

Sonographic risk assessment for an unplanned operative delivery: a prospective study

PURPOSE

To assess the value of pre-labor maternal and fetal sonographic variables to predict an unplanned operative delivery.

METHODS

In this prospective study, nulliparous women were recruited at 37.0-42.0 weeks of gestation. Sonographic measurements included estimated fetal weight, maternal pubic arch angle, and the angle of progression. We performed a descriptive and comparative analysis between two outcome groups: spontaneous vaginal delivery (SVD) and unplanned operative delivery (UOD) (vacuum-assisted, forceps-assisted and cesarean deliveries). Multivariate logistic regression with ROC analysis was used to create discriminatory models for UOD.

RESULTS

Among 234 patients in the study group, 175 had a spontaneous vaginal delivery and 59 an unplanned operative delivery. Maternal height and pubic arch angle (PAA) significantly correlated with UOD. Analysis of Maximum Likelihood Estimates revealed a multivariate model for the prediction of UOD, including the parameters of maternal age, maternal height, sonographic PAA, angle of progression (AOP), and estimated fetal weight, with an area under the curve of 0.7118.

CONCLUSION

Sonographic parameters representing maternal pelvic configuration (PAA) and maternal-fetal interface (AOP) improve the prediction ability of pre-labor models for a UOD. These data may aid the obstetrician in the counseling process before delivery.

Association of term isolated microcephaly with mode of delivery and perinatal outcome - a retrospective case-control analysis

Background

We aimed to evaluate the association of isolated fetal microcephaly measured by ultrasound prior to delivery at term with mode of delivery and perinatal outcome.

Methods

A single-center retrospective study was conducted in 2012–2016. Fetal microcephaly was defined as head circumference > 2 standard deviations of the mean for gestational age and sex. We compared the obstetric, delivery, and outcome parameters of women in whom ultrasound performed up to 10 days prior to term delivery showed isolated fetal microcephaly (study group) or normal head circumference (reference group). Exclusion criteria were intrauterine fetal death, birthweight below the 10th percentile, and antepartum cesarean delivery for any indication.

Results

Of 3677 women included in the study, 26 (0.7%) had a late ultrasound finding of isolated fetal microcephaly. Baseline characteristics were similar in the two groups except for estimated fetal weight based on abdominal circumference and biparietal diameter, which was lower in the microcephaly group (3209.8 ± 557.6 vs. 2685.8 ± 420.8 g, p < .001). There was no significant between-group difference in rate of vaginal operative deliveries (11.7% vs 14.8%, respectively, p = 0.372). The study group had no intrapartum cesarean deliveries compared to 6.3% of the reference group (NS). Compared to controls, neonates in the study group were smaller (3323.2 ± 432.2 vs. 2957.0 ± 330.4 g, p < .001), with lower birthweight percentile (60.5 ± 26.5 vs. 33.6 ± 21.5%, p < .001) and were more often males (48.2 vs. 90.0%, p < .001). No significant differences were noted in perinatal outcomes between the groups, including admission to neonatal intensive care unit, intraventricular hemorrhage, 5-min Apgar score < 7, asphyxia, seizures, and sepsis.

Conclusions

Isolated microcephaly in term fetuses is not advantageous for a vaginal delivery, nor does it does not pose a greater than normal risk of adverse perinatal outcome.

Influence of newborn head circumference and birth weight on the delivery mode of primipara: what is more important?

Objectives Aim of the study was to analyze the impact of head circumference (HC) and birth weight (BW) on the delivery mode and delivery outcomes. Methods Study population consisted of pregnancy, delivery and newborn data from 1,762 women, who delivered between 2004 and 2016 at University Hospital of Zurich (UHZ). Odds ratio (OR) with 95% confidence intervals (CI) were calculated for mode of delivery. Newborns were sorted into four groups according HC or BW. To evaluate the association between HC and delivery outcome, a descriptive analysis was performed. In addition reference charts of newborn HC at term were constructed. Results OR for instrumental delivery (ID) was 2.37 (CI 95%, 1.63-3.46), for C-Section (CS) 3.74 (CI 95%, 1.49-9.37) when HC >36 cm. OR for ID was 1.59 (CI 95%, 1.02-2.50), for CS 3.18 (CI 95% 1.08-9.350) when BW was >4,000 g. OR for ID was 2.15 (95% CI, 1.69-2.73), for CS 1.93 (95% CI, 0.89-4.18) when HC ≥36 cm and BW <4000 g. OR for ID was 2.23 (95% CI, 1.35-3.67), for CS 4.39 (95% CI, 1.48-12.99) when HC ≥36 cm and BW ≥4,000 g. HC ≥36 cm was defined as large in our study. Mothers with higher age and body mass index delivered babies with larger HC (p<0.05). Blood loss and duration of expulsion period and BW was associated with larger HC (p<0.05). Conclusions The rate of ID and CS increased in case of a larger HC and greater BW. However, the main prognostic factor for ID was size of HC: ≥36 cm, but not macrosomia.

Ultrasound in labor admission to predict need for emergency cesarean section: a prospective, blinded cohort study

OBJECTIVE

To assess whether assessment with ultrasound could improve the detection of emergency cesarean section (ECS) in laboring women.

METHODS

Women who presented with symptoms of active labor or women in need of labor induction were invited to participate in the study. Women included in the study were evaluated with ultrasonography for fetal biometry and vaginal examinations for Bishop score assessment. The main aim in this study was determining factors associated with ECS due to fetal distress and obstructed labor.

RESULTS

No fetal biometry variable was associated with ECS due to any indication (fetal distress and obstructed labor combined) in the univariate analysis. In multivariate analyses, biometry variables were adjusted for Bishop score at admission and only abdominal circumference percentile showed a significant association with the odds of ECS due to any indication (OR:1.02, 95% CI: 1.01-1.03). Biparietal diameter and abdominal circumference variables were associated with the odds of ECS due to obstructed labor in both univariate and multivariate analyses (p < .05 for all). However, the predictive accuracy of biparietal diameter percentile (area under the curve (AUC): 0.55, 95% CI: 0.46-0.63) and abdominal circumference percentile (AUC: 0.56, 95% CI: 0.48-0.64) without adjunct variables were poor. Moreover, the addition of fetal biometry parameters to Bishop score did not improve the predictive accuracy of Bishop score.

CONCLUSION

Ultrasound assessment at admission, in addition to Bishop score assessment, did not significantly improve the prediction of ECS. Also, the fetal biometry alone had poor predictive capability for ECS. Routine ultrasound assessment at labor admission appears to be ineffective for predicting ECS.PrecisFetal biparietal diameter and abdominal circumference showed an association with emergency cesarean due to obstructed labor but the predictive accuracy of fetal biometry was low. Routine ultrasound examination at admission, in addition to Bishop score assessment, may not useful for assessing the risk of emergency section in unselected populations.

Intracranial cystic lesions and polydactyly associated with acrocallosal syndrome: Sonographic findings in two cases

We describe two cases of intracranial cystic lesions associated with acrocallosal syndrome. These fetal anomalies were detected on antenatal sonography and confirmed postnatally. Imaging findings include corpus callosum agenesis with interhemispheric cysts and craniofacial anomalies associated with polydactyly. Identifying the above imaging features is of importance to plan management and provide supportive care that may be required.

Seizures in newborn infants without hypoxic ischemic encephalopathy - antenatal and labor-related risk factors: a case-control study

Objective: To identify antepartum and intrapartum risk factors for neonatal seizures in the absence of hypoxic ischemic encephalopathy (HIE).Methods: Population-based case-control study. Of 98 484 births, 40 newborns at 34 gestational weeks or later had seizures within the first 7 days of life. Cases (n = 40) and controls (n = 160) were retrieved from the University hospitals of Örebro for 1994-2013 and Uppsala for 2003-2013. Demographics and characteristics of pregnancy, labor, delivery, and neonatal data were analyzed. Crude odds ratio (OR) and adjusted odds ratios (AOR) with 95% confidence intervals (CIs) for antenatal and intrapartum factors were calculated using logistic regression analysis. Main outcome measure was neonatal seizures within the first 7 days of life.Results: The incidence of neonatal seizures without HIE was 0.41/1000 live births. Antenatal risk factors for neonatal seizures were as follows: short maternal stature (AOR: 5.4; 1.8-16.5); previous caesarean section (AOR: 4.8; 1.5-15.0); and assisted fertilization (AOR: 6.8; 1.3-35.2). Intrapartum risk factors were as follows: induction of labor (AOR: 5.7; 1.8-17.7); preterm birth (AOR: 13.5; 3.7-48.9); and head circumference >37 cm (AOR: 6.9; 1.4-34.8).Conclusions: Preterm birth was the strongest risk factor for neonatal seizures in the absence of HIE. The results also indicate that feto-pelvic disproportion is associated with the occurrence of seizures.Rationale: Antepartum and intrapartum risk factors for newborn seizures in the absence of HIE were investigated in a case-control study. Out of 98 484 births at 34 gestational weeks or more, 40 newborns had seizures without HIE. All had a normal Apgar score although they later presented with seizures. Preterm birth was the strongest risk factor (OR: 13.5; 95% CI: 3.7-48.9). Our results also indicate that feto-pelvic disproportion is of importance. Furthermore, a history of prior caesarean was associated with seizures. This is the first study to assess obstetric risk factors for newborn seizures separate from those with seizures and concomitant HIE. The distinction is of importance due to different etiologies, treatments, and preventive strategies.

The association between neonatal head circumference and second stage duration

Purpose: To determine if head circumference (HC) is an independent factor influencing second stage duration stratified by parity and epidural use.Materials and methods: A retrospective cohort analysis of all live, singleton, term (37-42 weeks) vaginal deliveries in one university affiliated medical center (2012-2014). Exclusion criteria included operative deliveries due to fetal distress, major fetal anomalies/chromosomal abnormalities or cases with missing anthropometric data. Maternal demographics, labor characteristics and neonatal anthropometrics including birth weight and HC were retrieved. Multivariate linear regression was utilized to evaluate the association between HC and second stage duration. Analysis was stratified into four groups by parity and epidural use.Results: Of the 16 240 singleton vaginal deliveries during study period, 12 428 deliveries met inclusion criteria. Stratification by parity and epidural analgesia yielded four groups: 3337 (26.9%), 735 (5.9%), 5099 (41.0%) and 3257 (26.2%) deliveries - nullipara with/without epidural and multipara with/without epidural, respectively. In all groups, a large neonatal HC was significantly and independently associated with longer second stage duration: nullipara with epidural (beta 10.06, 95% CI 7.75-12.37), nullipara without epidural (beta 7.58, 95% CI 4.73-10.43), multipara with epidural (beta 4.64, 95%CI 3.47-5.8) and multipara without epidural (beta 1.35, 95% CI 0.76-1.94), p < .001 for all. Birth weight was not associated with second stage duration in any of the groups (p > .05).Conclusion: Large neonatal HC is significantly associated with longer second stage duration.

Vacuum extraction failure is associated with a large head circumference

Objective: To determine whether large head circumference increases the risk of vacuum extraction failure. Study design: This EMR-based study included all attempted vacuum extractions performed in a tertiary center between January 2010 and June 2015. All term singleton live births were eligible. Cases were divided into four groups: head circumference ≥90th percentile both with birth weight ≥90th percentile and <90th percentile and fetal head circumference <90th percentile with birth weight ≥90th and <90th percentile. Risk of failed vacuum extraction was compared among these groups. Other neonatal and maternal parameters were also evaluated as potential risk factors. Multinomial multivariable regression provided adjusted odds ratio for vacuum extraction failure while controlling for potential confounders. Results: During the study period, 48,007 deliveries met inclusion criteria, of which 3835 had an attempt at vacuum extraction. We identified 215 (5.6%) cases of vacuum extraction failure. The adjusted odds ratios (aOR) for vacuum extraction failure in cases of large fetal head circumference was 2.31 (95%CI, 1.7-3.15, p < .001). Primiparity, prolonged second stage and occipito-posterior presentation were also found to be significant risk factors for failed vacuum extraction. Comments: In this study, we found that large head circumference was associated with vacuum extraction failure rather than high birth weight.

Sonographic large fetal head circumference and risk of cesarean delivery

BACKGROUND

Persistently high rates of cesarean deliveries are cause for concern for physicians, patients, and health systems. Prelabor assessment might be refined by identifying factors that help predict an individual patient's risk of cesarean delivery. Such factors may contribute to patient safety and satisfaction as well as health system planning and resource allocation. In an earlier study, neonatal head circumference was shown to be more strongly associated with delivery mode and other outcome measures than neonatal birthweight.

OBJECTIVE

In the present study we aimed to evaluate the association of sonographically measured fetal head circumference measured within 1 week of delivery with delivery mode.

STUDY DESIGN

This was a multicenter electronic medical record-based study of birth outcomes of primiparous women with term (37-42 weeks) singleton fetuses presenting for ultrasound with fetal biometry within 1 week of delivery. Fetal head circumference and estimated fetal weight were correlated with maternal background, obstetric, and neonatal outcome parameters. Elective cesarean deliveries were excluded. Multinomial regression analysis provided adjusted odds ratios for instrumental delivery and unplanned cesarean delivery when the fetal head circumference was ≥35 cm or estimated fetal weight ≥3900 g, while controlling for possible confounders.

RESULTS

In all, 11,500 cases were collected; 906 elective cesarean deliveries were excluded. A fetal head circumference ≥35 cm increased the risk for unplanned cesarean delivery: 174 fetuses with fetal head circumference ≥35 cm (32%) were delivered by cesarean, vs 1712 (17%) when fetal head circumference <35 cm (odds ratio, 2.49; 95% confidence interval, 2.04-3.03). A fetal head circumference ≥35 cm increased the risk of instrumental delivery (odds ratio, 1.48; 95% confidence interval, 1.16-1.88), while estimated fetal weight ≥3900 g tended to reduce it (nonsignificant). Multinomial regression analysis showed that fetal head circumference ≥35 cm increased the risk of unplanned cesarean delivery by an adjusted odds ratio of 1.75 (95% confidence interval, 1.4-2.18) controlling for gestational age, fetal gender, and epidural anesthesia. The rate of prolonged second stage of labor was significantly increased when either the fetal head circumference was ≥35 cm or the estimated fetal weight ≥3900 g, from 22.7% in the total cohort to 31.0%. A fetal head circumference ≥35 cm was associated with a higher rate of 5-minute Apgar score ≤7: 9 (1.7%) vs 63 (0.6%) of infants with fetal head circumference <35 cm (P = .01). The rate among fetuses with an estimated fetal weight ≥3900 g was not significantly increased. The rate of admission to the neonatal intensive care unit did not differ among the groups.

CONCLUSION

Sonographic fetal head circumference ≥35 cm, measured within 1 week of delivery, is an independent risk factor for unplanned cesarean delivery but not instrumental delivery. Both fetal head circumference ≥35 cm and estimated fetal weight ≥3900 g significantly increased the risk of a prolonged second stage of labor. Fetal head circumference measurement in the last days before delivery may be an important adjunct to estimated fetal weight in labor management.