Mode of delivery
All enrolled 100-case pregnant women accepted the suggestion of vaginal delivery after admission, including one case fetal death in uterus also accepted vaginal delivery by induced labor. This dead fetal was diagnosed as having the UCAN for 4 loops and knotting confirmed by examination after delivery. Thirty-five cases of emergency cesarean section for various reasons after parturition. Selective cesarean section was performed in only five-case pregnant women with a strong desire for cesarean section after parturition. And 47-case pregnant women had experienced successfully natural vaginal delivery, 13 cases had done forceps delivery because of abnormal fetal position.
Prenatal factors of 100-case pregnant women
The comparison of age, gestational week and AFI between two groups all showed no great significance, all P value >0.05. And the comparison of S/D, UCAN, DFMC, NST and mode of delivery all showed remarkable difference between two groups, all P value <0.05 (Table 1).
Table 1 Comparison of different risk factors affecting fetal intrauterine safety between different groups (M±SD), [n (%)].
Factors IUS [n=65] IUNS [n=56] t/x2 P
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Age (years) 27.34±5.38 28.75±5.26 -1.456 0.148
Gestational week(weeks) 39.32±1.02 39.17±1.37 0.655 0.514
S/D (value) 2.41±0.35 2.52±0.30 -1.752 0.082
AFI (centimeter) 10.10±3.22 9.98±2.52 0.226 0.821
UDCA (loop) 26.130 0.000
1 [27] 22(81.48) 5(18.52)
2 [42] 18(58.06) 14(41.94)
≥3 [52] 11(24.44) 34(75.56)
FM (DFMC) 53.880* 0.000
Normal [62] 58(89.20) 4(7.10)
Irregular [23] 2(3.10) 21(37.50)
Decrease/Absence [36] 5(7.70) 31(55.40)
NST (scores) 24.292* 0.000
≥8 [91] 62(68.13) 29(46.70)
[6-7] [22] 2(4.50) 20(35.70)
≤5 [8] 1(2.30) 7(12.50)
Mode of delivery 61.742* 0.000
Natural vaginal [68] 58(85.29) 10(14.71)
Cesarean section [40] 3(6.80) 37(66.10)
Forceps [13] 4(9.10) 9(16.10)
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M±SD: Mean±standard deviation, IUS: Intrauterine safety, IUNS: Intrauterine non safety, S/D: Systolic period and diastolic period blood flow ratio of umbilical artery under ultrasound. AFI: Amniotic fluid index. *showed by Chi-square test.
Logistic regression analysis of high risk factors which affected the influence of fetal intrauterine safety
The results of binary logistic stepwise regression analysis showed that DFMC and mode of delivery were the influencing factors of the outcome of fetal intrauterine security, FM (Wald=13.286, P=0.000) and mode of delivery (Wald= 21.816, P=0.000) in detail. The Exp (B) and (95%CI) of abnormal DFMC were separately 22.065 (4.155-117.178) for irregular FM and 21.282 (3.443-131.588) for decrease FM compared with normal FM (Table 2).
Table 2 Logistic regression analysis of high-risk factors that effects fetal intrauterine safety.
Variables B SE Wald Exp(B) 95%CI (Lower -Upper ) P
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Step1
Age(years) 0.053 0.067 0.431 1.054 0.924-1.202 0.431
GA(week) 0.322 0.288 1.246 1.379 0.784-2.426 0.264
S/D(value) -0.128 1.012 0.016 0.880 0.121-6.398 0.899
AFI(cm) 0.038 0.103 0.138 1.039 0.848-1.273 0.710
UDCA(loop) 2.524 0.283
UDCA(2 ) -1.426 1.109 1.654 0.240 0.027-2.211 0.198
UDCA(≥3 ) -1.797 1.136 2.501 0.166 0.018-1.537 0.114
FM(DFMC) 13.484 0.001
Irregular 4.053 1.162 12.173 57.553 5.907-560.709 0.007
Decrease/Absence
3.513 1.266 7.697 33.563 2.805-401.607 0.068
NST 2.524 0.283
[6-7] 1.672 1.065 2.464 5.321 0.660-42.960 0.117
≤5 0.674 1.293 0.272 1.962 0.156-24.722 0.602
Mode of delivery 17.191 0.000
Cesarean 3.120 0.918 11.546 22.642 3.744-136.909 0.001
Forceps 2.910 0.996 8.541 18.348 2.607-129.132 0.003
Constant -17.190 12.229 1.976 0.000 0.160
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Step2
FM(DFMC) 13.286 0.001
Irregular 3.094 0.852 13.190 22.065 4.155-117.178 0.000
Decrease 3.058 0.929 10.825 21.282 3.443-131.588 0.001
Mode of delivery 21.868 0.000
Cesarean 3.249 0.865 14.121 25.763 4.732-140.259 0.000
Forceps 3.058 0.929 10.825 21.282 3.443-131.558 0.001
Constant -3.369 0.755 19.893 0.034 0.000
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B: Partial regression index coefficient, SE: Standard Error, Wald: the square of B/SE. Exp (B): Odds Ration. Note: binary logistic stepwise regression analysis, Dependent variable: fetal intrauterine safety (safety: 0; non safety: 1), Independent variables: Age, gestational week, S/D, AFI, UDCA (1-2 loops: 0; ≥3 loops: 1), DFMC (regular: 0; irregular: 1; Decrease/absence: 2), NST (≥8: 0; 6-7: 1; ≤5: 2), Mode of delivery (natural vaginal: 0; Cesarean section: 1; Forceps: 2).
Comparison of DFMC predictive evaluation before delivery and retrospective evaluation after delivery
There was no significant difference between DFMC prediction before delivery and clinical retrospective evaluation of intrauterine fetal safety after delivery, all P value of different mode of delivery showed greater than 0.05, only except for mode of cesarean delivery showed great significance (Table 3). This result completely confirmed the conclusion that the predictive value of DFMC was basically consistent with the clinical outcome in the mode of natural vaginal delivery. And the predictive efficacy of DFMC in different delivery modes showed natural vaginal delivery was the best, PPV, NPV, sensitivity, specificity and Yuden index were respectively 96.7%, 64.3%, 86.5%, 90.0% and 0.77. Besides, the predictive efficacy of DFMC in cesarean delivery was the second, but with the highest specificity of 94.6% (Table 3).
Table 3 the comparisons between DFMC prediction and clinical results under different delivery modes and evaluating indicators of DFMC (%).
DFMC prediction Clinical results DFMC prediction before delivery
Before delivery After delivery Evaluating indicators (%)
MD n Y N Y N P PPV NPV SE SP YI
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NVD 68 44 24 37 10 0.795 96.7 64.3 86.5 90.0 0.77
CSD 40 4 36 3 37 0.000 50.0 97.2 66.7 94.6 0.61
FRD 13 5 8 4 9 0.428 28.6 66.7 50.0 44.4 -0.06
Total 121 53 58 44 56 - 81.8 85.7 81.8 85.7 0.68
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MD: Model of delivery, n: case number, Y: safety, N: no safety, PPV: Positive prediction value, NPV: Negative prediction value, SE: Sensibility, SP: Specificity, YI: Yuden’s Index.
Analysis of the distribution of reasons for cesarean section delivery
The distribution of prenatal reasons for 40-case pregnant women by cesarean section delivery showed that the proportion of abnormal DFMC, fetal position and UCAN (≥3 loops) were separately 87.5%, 62.5% and 62.5%. This result also showed that the predictive value of DFMC on fetal intrauterine safety was the best. And the distribution of postpartum reasons showed the proportion of amniotic fluid (≥II) was the highest, with the rate of 47.5%, followed by asphyxia(Y) and Apgar’s score (≤6),with the rates of 40.0% and 35.0% (Table 4).
Table 4 Distribution of reasons for 40-case cesarean section delivery [n (%)]
Fetal factors UD factors(UCAN/knot) Amniotic fluid Apgar’s score Asphyxia(Y/N)
A- DFMC FS FP 1 2 ≥3 knot Normal I ≥II ≥7 ≤6 Y N
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E-CS 35(28.9) 10(9.2) 25(20.7) 2(1.7) 8(6.6) 25(20.7) 3(2.5) 8(6.6) 12(9.9) 18(14.9) 21(17.4) 14(11.6) 16(13.2) 19(15.7)
S-CS 0 0 0 1(1.0) 4(4) 0 0 1 0 0 5(5.0) 0 0 5(5.0)
P-ECS 87.5 25.0 62.5 5.0 20.0 62.5 7.5 20.0 35.0 47.5 52.5 35.0 40.0 47.5
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E-CS=Emergency CS, S-CS=Selective CS, P-ECS=Proportion of emergency CS, A-DFMC=Abnormal DFMC, FS=Fetal Stress, FP=Fetal Position, Y: asphyxia, N: non asphyxia. UCAN=Umbilical cord around neck.