Predictive value of uterine electromyography combined with cervical length for preterm birth

doi:10.3877/cma.j.issn.2095-3259.2026.03.008

Abstract

Abstract:

Objective

To analyze the uterine electromyography (EMG) characteristics of primiparous women with threatened preterm labor and to evaluate the value of uterine EMG combined with cervical length in predicting preterm birth.

Methods

This was a prospective observational cohort study. Primiparous women at 24-34 weeks of gestation with symptoms of threatened preterm labor who presented to the obstetrics clinic or emergency department of our hospital were enrolled. Uterine EMG and cervical length measurements were performed. Clinical characteristics, cervical length, pregnancy outcomes, and uterine EMG parameters including burst wave frequency (number of burst waves per 30 minutes), burst duration, maximum power density spectrum (PDS) frequency, and total power were recorded and analyzed. ROC curves for predicting delivery within 7 days were constructed using uterine EMG parameters and cervical length, alone and in combination.

Results

A total of 209 pregnant women were included. Based on the time interval from enrollment to delivery, they were divided into three groups: delivery within 48 hours (n=20), delivery within 3-7 days (n=22), and delivery after more than 7 days (n=167). The total power of uterine EMG burst waves in the within-48-hours delivery group was significantly higher than that in the 3-7 days delivery group and the >7 days delivery group, with mean differences (I-J) of -3.13 and -4.47, respectively (both P<0.001). The total power in the 3-7 days delivery group was significantly higher than that in the >7 days delivery group, with a mean difference (I-J) of -1.34 (P<0.001). There were no statistically significant differences in the number of burst waves, burst duration, or maximum PDS among the three groups (all P>0.05). The AUC of total power for predicting delivery within 7 days was 0.88, with a sensitivity of 76.0% and a specificity of 86.2%. The AUC of cervical length for predicting delivery within 7 days was 0.71, with a sensitivity of 74.0% and a specificity of 63.0%. When uterine EMG total power was combined with cervical length, the AUC for predicting delivery within 7 days increased to 0.92, with a sensitivity of 81.0% and a specificity of 90.0%.

Conclusions

An increase in uterine EMG burst wave total power may indicate an increased risk of preterm birth. The combination of uterine EMG and cervical length can improve the accuracy of predicting delivery within 7 days in women with threatened preterm labor.

Key words: Uterine electromyography, Preterm birth, Predicting, Uterine contraction, Cervical length measurement

Pin Li, Miaoting Zhou, Fanxing Zhao, Lele Wang, Qian Huang, Zheng Zheng, Yunshan Chen, Guozheng Zhang, Huishu Liu. Predictive value of uterine electromyography combined with cervical length for preterm birth[J]. Chinese Journal of Obstetric Emergency(Electronic Edition), 2026, 15(03): 175-181.

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References 27

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组别	例数	年龄[岁，M(Q₁，Q₃)]	体重指数[kg/m²，M(Q₁，Q₃)]	检测孕周[周，M(Q₁，Q₃)]	孕次[次，M(Q₁，Q₃)]	IVF-ET[例(%)]	地塞米松[例(%)]	宫缩抑制剂[例(%)]	宫颈长度[mm，M(Q₁，Q₃)]
48 h内分娩组	20	29(29，31)	25.51(23.73，26.89)	32(30，33)	2(1，4)	2(10.00)	15(75.00)	13(65.00)	15.50(8.50，18.25)^a
3~7 d分娩组	22	31(28，35)	25.20(21.68，26.61)	30(29，33)	2(1，5)	3(13.64)	20(90.91)	18(81.82)	15.50(10.25，20.75)^b
>7 d分娩组	167	31(29，35)	24.77(22.38，26.45)	31(29，33)	2(1，5)	19(11.38)	118(70.66)	97(58.08)	23.00(15.00，32.50)
统计值		H＝1.97	H＝0.80	H＝1.63	H＝3.37	χ²＝0	χ²＝4.10	χ²＝4.78	H＝17.39
P值		0.37	0.67	0.44	0.18	0.92	0.13	0.09	<0.001

组别	例数	年龄[岁，M(Q₁，Q₃)]	体重指数[kg/m²，M(Q₁，Q₃)]	检测孕周[周，M(Q₁，Q₃)]	孕次[次，M(Q₁，Q₃)]	IVF-ET[例(%)]	地塞米松[例(%)]	宫缩抑制剂[例(%)]	宫颈长度[mm，M(Q₁，Q₃)]
48 h内分娩组	20	29(29，31)	25.51(23.73，26.89)	32(30，33)	2(1，4)	2(10.00)	15(75.00)	13(65.00)	15.50(8.50，18.25)^a
3~7 d分娩组	22	31(28，35)	25.20(21.68，26.61)	30(29，33)	2(1，5)	3(13.64)	20(90.91)	18(81.82)	15.50(10.25，20.75)^b
>7 d分娩组	167	31(29，35)	24.77(22.38，26.45)	31(29，33)	2(1，5)	19(11.38)	118(70.66)	97(58.08)	23.00(15.00，32.50)
统计值		H＝1.97	H＝0.80	H＝1.63	H＝3.37	χ²＝0	χ²＝4.10	χ²＝4.78	H＝17.39
P值		0.37	0.67	0.44	0.18	0.92	0.13	0.09	<0.001

组别	例数	爆发波个数[个，M(Q₁, Q₃)]	持续时间[s，M(Q₁, Q₃)]	最大PDS[Hz，±s]	总功率[pV2，M(Q₁, Q₃)]
48 h内分娩组	20	3(3，4)	30.93(26.90，35.97)	0.56±0.08	7.58(6.10，9.67)^a
3~7 d分娩组	22	3(2，4)	30.75(27.69，36.56)	0.57±0.08	5.14(4.42，5.77)^b
>7 d分娩组	167	3(2，3)	31.00(27.92，34.00)	0.54±0.08	4.03(3.24，4.56)^c
统计值		H＝3.44	H＝0.39	F＝1.70	H＝63.88
P值		0.18	0.82	0.19	<0.001

组别	例数	爆发波个数[个，M(Q₁, Q₃)]	持续时间[s，M(Q₁, Q₃)]	最大PDS[Hz，±s]	总功率[pV2，M(Q₁, Q₃)]
48 h内分娩组	20	3(3，4)	30.93(26.90，35.97)	0.56±0.08	7.58(6.10，9.67)^a
3~7 d分娩组	22	3(2，4)	30.75(27.69，36.56)	0.57±0.08	5.14(4.42，5.77)^b
>7 d分娩组	167	3(2，3)	31.00(27.92，34.00)	0.54±0.08	4.03(3.24，4.56)^c
统计值		H＝3.44	H＝0.39	F＝1.70	H＝63.88
P值		0.18	0.82	0.19	<0.001

组别	例数	年龄[岁，M(Q₁，Q₃)]	体重指数[kg/m²，M(Q₁，Q₃)]	检测孕周[周，M(Q₁，Q₃)]	孕次[次，M(Q₁，Q₃)]	IVF-ET[例(%)]	地塞米松[例(%)]	宫缩抑制剂[例(%)]	宫颈长度[mm，M(Q₁，Q₃)]
>7 d分娩组	167	31(29，35)	24.77(22.38，26.45)	31(29，33)	2(1，2)	19(11.38)	118(70.66)	97(58.08)	23.00(15.00，32.25)
7 d内分娩组	42	30(28，35)	25.39(23.28，26.68)	32(29，33)	2(1，3)	6(11.90)	35(83.33)	31(73.81)	15.00(10.00，19.75)
统计值		Z＝－1.02	Z＝－0.77	Z＝－0.37	Z＝－1.69	χ²＝0.00	χ²＝2.75	χ²＝3.50	Z＝－4.12
P值		0.31	0.44	0.71	0.09	1.00	0.10	0.06	<0.001

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