Association between a low umbilical artery pulsatility index and fetal distress in labor in very prolonged pregnancies

Developmental data in preschool children born after prolonged pregnancy

AIM

To evaluate children born post-term (gestational age>or=42 weeks) with respect to developmental data obtained at the ages of 4 and 5.5 y.

METHODS

The study population included all children (n=354) born in 1991 at Huddinge University Hospital with a gestational age of >or=42 wk. The births were identified and perinatal data were collected through the Swedish National Birth Registry. Developmental assessments from the child health centres were analysed. Children born at term, but before a gestational age of 42 wk, served as controls. Logistic regression analysis was used to analyse the data.

RESULTS

Children born post-term had more developmental deviations than the controls (estimated odds ratio 2.20; 95% CI: 1.29-3.85). Boys had more deviations than girls (estimated odds ratio 1.92; 95% CI: 1.11-3.45).

CONCLUSION

Our results indicate that there might be an association between post-term birth and developmental deviations.

Use of umbilical-cerebral Doppler ratios in predicting fetal growth restriction in near-term fetuses

OBJECTIVE

To compare the sensitivity and specificity of different umbilical-cerebral ratios in the prediction and detection of fetal growth restriction in near-term fetuses when the umbilical arterial waveform is within normal.

METHODS

A prospective cross-sectional observational study was carried out recruiting consecutive singleton pregnancies with clinically suspected fetal growth restriction after 34 weeks gestation. The umbilical-cerebral ratios were then calculated from the S/D, RI and PI values and correlated with immediate perinatal outcome.

RESULTS

A total of 187 patients were recruited. Twelve cases had abnormal UA Doppler flow velocity waveform studies. Of the 175 with normal UA Doppler findings, 92 (53.1%) were confirmed to have fetal growth restriction (FGR) with birth weights below the tenth centile for gestation. The detection rate of FGR by ultrasound biometry was 96.7%. The mean umbilical artery S/D, RI and PI values were higher in the fetal growth restriction group, while the middle cerebral artery values were lower as compared to fetuses with no growth restriction. A small but significant difference was seen in the umbilical-cerebral ratios of the different indices between the two groups. Receiver operator characteristic curves showed that there was little difference between the performances of the S/D, RI or PI ratios and all had limited power in predicting fetal growth restriction.

CONCLUSION

In the presence of normal umbilical artery Doppler waveforms, umbilical-cerebral ratios have limited power to predict fetal growth restriction.

Low umbilical artery vascular flow resistance and fetal outcome

BACKGROUND

An abnormally high [above mean + 2 standard deviations (SD)] umbilical artery (UA) pulsatility index (PI) indicates impaired fetal outcome, whereas the impact of an "abnormally" low (below mean -2 SD) PI is unknown.

METHODS

Perinatal outcome was compared between cases with a UA PI less than mean -2 SD (group A: high-risk cases selected from a database, n = 330; group B: unselected cases, n = 39) and unselected controls (group C) with a PI within mean +/- 2 SD (n = 863) at Doppler velocimetry. Groups B and C were retrieved from a population-based sample. The unpaired t-test, Mann-Whitney U-test, chi(2)-test and Fisher's exact probability test were used for statistical comparisons with a two-tailed p < 0.05 being significant.

RESULTS

No significant differences were found between group A vs. group C and group B vs. group C regarding perinatal mortality, Apgar scores at 1, 5 or 10 min, or arterial or venous cord blood pH. Postterm pregnancy in group A carried no additional risk. For obvious reasons, operative delivery and neonatal intensive care were more common in group A than in group C, but no such differences were found between groups B and C. The mean birthweight was 3.7% higher in group B than in group C (p = 0.049).

CONCLUSIONS

Deeming a UA PI below the lower reference limit as "abnormally" low is a statistical definition that was not reflected by a biological imperfection. Instead, a low UA PI promoted fetal growth.

Fetal cerebral blood flow redistribution in late gestation: identification of compromise in small fetuses with normal umbilical artery Doppler

OBJECTIVE

To evaluate the role of middle cerebral artery Doppler in small fetuses during the late third trimester.

DESIGN

Prospective observational study of structurally normal fetuses with an estimated fetal weight < 5th percentile for gestation. Perinatal outcome was determined using a structured datasheet sent to each referring obstetrician.

SUBJECTS

Structurally normal fetuses at 35 or more weeks of gestation referred during a 2-year period to the fetal growth clinic of a regional fetal medicine unit in North London. Fetuses with aneuploidy and/or major structural abnormalities were excluded.

METHODS

Umbilical artery and middle cerebral artery (MCA) Doppler waveforms were recorded and considered abnormal if above 95th or below 5th percentiles, respectively. Amniotic fluid was considered reduced if the maximum vertical cord-free pool was < 2 cm. The placenta was considered mature if the Grannum grade was II or III. The head circumference (HC)/abdominal circumference (AC) ratio was considered abnormal if > 95th percentile for gestation. Fetal growth, amniotic fluid, biophysical profile score and umbilical artery Doppler were used to advise the referring obstetrician about fetal well-being and he/she independently decided both the timing and mode of delivery.

RESULTS

Forty-seven fetuses fulfilled the entry criteria. Thirty-four (72%) demonstrated normal umbilical artery Doppler waveforms. Sixteen (34%) demonstrated middle cerebral artery redistribution, of which nine (56%) had normal umbilical artery Doppler waveforms. MCA blood flow redistribution was associated with an increased incidence of cesarean delivery and need for neonatal admission. Of all gray-scale parameters, an elevated HC/AC ratio has the strongest association with MCA blood flow redistribution (15/16 vs. 1/31; P < 0.01).

CONCLUSIONS

MCA Doppler may be a useful tool to assess the health of small fetuses in the late third trimester. Redistribution may occur in the presence of normal umbilical artery Doppler and should be suspected when the HC/AC ratio is elevated.