A total of 23 pregnant women in 24 to 34 weeks of gestational age were enrolled. Elective pregnancy termination was done for nine cases at 34 weeks of gestation (Table 1). In the remaining 14 cases that terminated their pregnancy before 34 weeks of gestation, nine cases had labor pain and five cases had fetal distress, non-stress test category 3, or placental abruption. The mean latency period was 1.53 weeks in 23 fetuses.
Table 1. Demographic characteristic of 23 PPROM cases
||Estimated Weight at admission (25)
||Amniotic Fluid Index (cm)
||Gestational age at admission (week + day)
||Birth weight (25)
||Gestational age at birth (week + day)
||Apgar 1 minute
||Normal vaginal delivery
||Early neonatal Sepsis
The latency period of all cases based on neonatal complications is shown in Table 2. As the Apgar scores were not normally distributed, the median and 25, 50, and 75 percentiles for 1-minute Apgar were 9, 8, 9 and 9, respectively; also for 5-minute Apgar scores were 10, 9, 10, and 10.
Table 2. Latency period of all cases in separation of neonatal complications.
||Number of neonates
||Latency period (day)
|IVH grade 4
|IVH grade 1
Table 3. Differences in Pulsatility index of Doppler parameters for RDS cases and non-RDS cases, *: P<0.05
||95% Confidence Interval
||Admission MCA PI
||Termination MCA PI
||Admission Aorta PI
||Termination Aorta PI
||Admission renal artery PI
||Termination renal artery PI
||Admission Pulmonary artery PI
||Termination Pulmonary artery PI
||Admission UMA PI
||Termination UMA PI
Key: MCA: middle cerebral artery; UMA: fetal umbilical artery; SD: standard deviation
PPROM is the common cause of preterm labor and prematurity (26, 27). After its diagnosis, treatment and decision on pregnancy termination time can have a major influence on the neonatal outcome. The decision regarding the pregnancy termination of women with PPROM is made based on their health status at 34 weeks of gestation, evidence of chorioamnionitis, and intrauterine fetal distress (28-30). Few studies have examined different methods of fetal health assessment to improve maternal and neonatal outcomes; but none of them have reached firm conclusions on how to use these methods to predict outcomes (2, 5, 13). Using fetal assessment methods may lead to early detection of intrauterine infection that has a significant impact on maternal and neonatal outcomes; however, if these methods are not accurate, they can have devastating effects on the outcome by causing preterm birth (3).
A review article evaluated three studies that had used non-stress test, biophysical profile, and vaginal ultrasound imaging for fetal health assessment, but failed to show their impact on the outcome (3). Appropriate blood flow via umbilical cord and fetal arteries has a critical role in prenatal development. Vascular tone regulates this flow and some mediators can change this tone such as nitric oxide, prostacyclin, and thromboxane A2, which are basically produced during inflammatory processes. Prenatal changes in systemic homodynamic can be evaluated via Doppler ultrasound imaging (31).
In our study, variation in the fetal artery Doppler ultrasound imaging as a noninvasive method was evaluated as a possible method for predicting intrauterine complications and appropriate pregnancy termination time.
Generally, among the 23 cases studied in this study, a significant increase in the kidney artery PI was seen at pregnancy termination time compared to the admission time. According to kidney artery resistance curves, the PI decreases with an increase in the gestational age (32). Similarly, a significant reduction was observed in the pulmonary artery PI at pregnancy termination time in our patients compared to admission time. This is not consistent with studies that had reported increased pulmonary artery PI with an increase in the gestational age (24). This significant inverse relationship requires further investigation because it may be due to the effect of cytokines on the vascular tone. According to a study, chorioamnionitis, elevated pro-inflammatory and inflammatory cytokine concentrations, and cytokine-associated systemic hemodynamic disturbances in premature infants born after chorioamnionitis can expose infants to many complications (33).
The negative correlation between the umbilical artery PI and the 5-minute Apgar score may be due to the lower gestational age in neonates with a higher umbilical artery PI; therefore, future studies should evaluate fetuses at the same gestational age to investigate the relationship between umbilical artery resistance and Apgar score.
Sepsis was confirmed in one neonate who died one day after birth. Through comparing this neonate with other neonates the following results might be reported:
- In this case PPROM occurred at 27 weeks and 4 days of gestational age and pregnancy was terminated at 29 weeks of gestation. According to normal curves (34), a higher level of middle cerebral artery PI was expected in this patient compared to the mean levels of other patients while the PI showed a significant decrease at admission and pregnancy termination times.
- The resistance of the descending aorta does not change at different gestational ages, but a significant decrease in the descending aorta PI in this infant at the time of admission and termination is an interesting finding.
- A reduction in the kidney artery PI was reported with an increase in the gestational age (34); in addition, the kidney artery PI at pregnancy termination time in this patient showed a significant decrease in comparison with other neonates at a higher gestational age
- Although we expected an increase in the main pulmonary artery PI with an increase in the gestational age based on normal curves (35), we witnessed a significant decrease in this index at pregnancy termination time
- We found a noticeable reduction in the termination of fetal umbilical artery PI in this 29-week-old fetus compared to other fetuses with a higher gestational age. These changes in Doppler ultrasound imaging indexes in sepsis should be considered in future studies to develop a method to predict sepsis in PPROM fetus. This is maybe due to the vasodilator effect of released cytokines during sepsis.
The kidney artery PI showed a significant decrease in nine respiratory distress cases at pregnancy termination time compared to the admission time; however, there were no obvious changes in the main pulmonary artery PI index. Normally, the kidney artery PI decreases with an increase in the gestational age (32); therefore, its decrease is considerable in fetuses that later develop respiratory distress compared to fetuses without this complication. This may also be due to the effect of inflammatory cytokines. However, sepsis was not proved in these neonates. Similarly, in two neonates with intraventricular hemorrhage (grades 1 and 4) a significant decrease was seen in the umbilical artery PI after PPROM diagnosis and at the end of pregnancy in comparison with other fetuses; however, no significant changes were observed in middle cerebral artery PI.
According to our results, fetal artery’s Doppler ultrasound imaging assessment and variations in kidney and umbilical artery PI may predict occurrence of neonatal complications, such as respiratory distress and intraventricular hemorrhage. Since these complications can be influenced by multiple factors, further investigations are needed to clarify the pathophysiology and reproducibility of these findings. The main limitation of this study was its relatively small sample size. As far as the researchers investigated, there were no similar studies in the literature; hence, it is recommended that future studies evaluate this subject more comprehensively and report their own results.
Preterm birth because of PPROM results in many adverse neonatal outcomes; therefore, its early detection is effective in prevention of intrauterine complications and appropriate management of pregnancy termination. We found correlations between changes in the fetal arteries’ Doppler ultrasound imaging indexes and neonatal outcomes; variations in the PI of this noninvasive method can be used for accurate prediction of neonatal outcomes of women with PPROM.
The authors would like to thank Muhammed Hussein Mousavinasab for his sincere cooperation in editing this text.
Compliance with Ethical Standards
Disclosure of Conflict of interest
The authors declared that they have no conflict of interest.
Research Involving Human Participants
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards
Informed consent was obtained from all participants with assurance of confidentiality and anonymity of the data.
Conflicts of Interest
Authors declared no conflict of interests.