J Clin Gynecol Obstet

Journal of Clinical Gynecology and Obstetrics, ISSN 1927-1271 print, 1927-128X online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Gynecol Obstet and Elmer Press Inc

Journal website https://www.jcgo.org

Original Article

Volume 9, Number 4, December 2020, pages 102-107

Urethral Diameter at the Time of Birth and Its Implication on Urinary Incontinence

Figure 1. Pelvic floor ultrasound, midsagittal plane at rest. Arrow indicates the position of the symphysis pubis, i.e., point of reference for urethral measures. 1: urethral diameter at the mid urethra; 2: urethral diameter at the bladder neck.

**Table 1.** Patients Characteristics
Variables	Total (n = 151)	Vaginal birth (n = 73)	Cesarean section (n = 78)	P value*
*Student’s t- or Mann-Whitney test for independent samples. Significance set as P ≤ 0.05 for all analysis. BMI: body mass index; SEM: standard error of the mean; CI: confidence interval; P: statistical significance.
Age, median (95% CI), years	26.41 (24.51 - 26.57)	22.36 (21.17 - 23.56)	29.50 (27.14 - 29.88)	≤ 0.0001
Height, median (95% CI), m	1.60 (1.60 - 1.62)	1.61 (1.59 - 1.62)	1.60 (1.59 - 1.62)	0.343
Initial gestational weight, median (95% CI), kg	67.00 (65.80 - 70.76)	62.00 (61.56 - 68.43)	69.50 (67.85 - 74.85)	0.008
Final gestational weight, mean ± SEM, kg	79.91 ± 1.26	77.38 ± 1.82	82.27 ± 1.71	0.052
Final gestational BMI, mean ± SEM, kg/m²	30.95 ± 0.44	29.77 ± 0.59	32.05 ± 0.64	0.010
Gestational weight gain, mean ± SEM, kg	11.63 ± 0.48	12.39 ± 0.62	10.92 ± 0.71	0.122
Previous pregnancies, median (95% CI)	1.00 (1.43 - 1.70)	1.00 (1.09 - 1.34)	2.00 (1.67 - 2.10)	≤ 0.0001
Previous vaginal births, median (95% CI)	0.00 (0.00 - 0.00)	0.00 (0.00 - 0.00)	0.00 (0.00 - 0.00)	1.000

Table 1. Patients Characteristics

Variables

Total (n = 151)

Vaginal birth (n = 73)

Cesarean section (n = 78)

P value*

*Student’s t- or Mann-Whitney test for independent samples. Significance set as P ≤ 0.05 for all analysis. BMI: body mass index; SEM: standard error of the mean; CI: confidence interval; P: statistical significance.

Age, median (95% CI), years

26.41 (24.51 - 26.57)

22.36 (21.17 - 23.56)

29.50 (27.14 - 29.88)

≤ 0.0001

Height, median (95% CI), m

1.60 (1.60 - 1.62)

1.61 (1.59 - 1.62)

1.60 (1.59 - 1.62)

0.343

Initial gestational weight, median (95% CI), kg

67.00 (65.80 - 70.76)

62.00 (61.56 - 68.43)

69.50 (67.85 - 74.85)

0.008

Final gestational weight, mean ± SEM, kg

79.91 ± 1.26

77.38 ± 1.82

82.27 ± 1.71

0.052

Final gestational BMI, mean ± SEM, kg/m²

30.95 ± 0.44

29.77 ± 0.59

32.05 ± 0.64

0.010

Gestational weight gain, mean ± SEM, kg

11.63 ± 0.48

12.39 ± 0.62

10.92 ± 0.71

0.122

Previous pregnancies, median (95% CI)

1.00 (1.43 - 1.70)

1.00 (1.09 - 1.34)

2.00 (1.67 - 2.10)

≤ 0.0001

Previous vaginal births, median (95% CI)

0.00 (0.00 - 0.00)

1.000

**Table 2.** Maternal Clinical Characteristics
Variables	Total (n = 151)	Vaginal birth (n = 73)	Cesarean section (n = 78)	P value*
*Chi-square test with adjusted residuals. Significance set as P ≤ 0.05 for all analysis. n: absolute frequency; n%: relative frequency; P: statistical significance.
Urinary tract infection during pregnancy, n (n%)	40 (26.5)	21 (28.8)	19 (24.4)	0.668
Diabetes mellitus, n (n%)	9 (6.0)	2 (2.7)	7 (9.0)	0.203
Hypertension, n (n%)	20 (13.2)	4 (5.5)	16 (20.5)	0.013

Table 2. Maternal Clinical Characteristics

Variables

Total (n = 151)

Vaginal birth (n = 73)

Cesarean section (n = 78)

P value*

*Chi-square test with adjusted residuals. Significance set as P ≤ 0.05 for all analysis. n: absolute frequency; n%: relative frequency; P: statistical significance.

Urinary tract infection during pregnancy, n (n%)

40 (26.5)

21 (28.8)

19 (24.4)

0.668

Diabetes mellitus, n (n%)

9 (6.0)

2 (2.7)

7 (9.0)

0.203

Hypertension, n (n%)

20 (13.2)

4 (5.5)

16 (20.5)

0.013

**Table 3.** Perinatal and Maternal Characteristics
Variables	Total (n = 151)	Vaginal birth (n = 73)	Cesarean section (n = 78)	P value*
^aVaginal birth (n = 5) and cesarean section (n = 4). ^bVaginal birth (n = 64) and cesarean section (n = 67). *Chi-square test with adjusted residuals, Student’s t- or Mann-Whitney test for independent samples. Significance set as P ≤ 0.05 for all analysis. UI: urinary incontinence; n: absolute frequency; n%: relative frequency; SEM: standard error of mean; P: statistical significance.
UI during pregnancy, n (n%)
Stress UI	56 (37.1)	30 (41.1)	26 (33.3)	0.324
Urge UI	37 (24.5)	19 (26.0)	18 (23.1)	0.817
Trimester of onset of UI symptoms, n (n%)				0.650
First	8 (5.3)	5 (6.8)	3 (3.8)
Second	7 (4.6)	3 (4.1)	4 (5.1)
Third	55 (36.4)	29 (39.7)	26 (33.3)
Birth weight, mean ± SEM, g	3,164.4 ± 226.4	3,081.2 ± 51.0	3,034.6 ± 80.7	0.626
Urethral diameter (level of the bladder neck)^b, mean ± SEM, mm	5.3 ± 0.6	5.6 ± 0.2	4.3 ± 0.2	≤ 0.0001
Urethral diameter (level of the median urethra), mean ± SEM, mm	5.6 ± 0.5	6.4 ± 0.2	6.6 ± 0.2	0.505
UI 6 months after birth, n (n%)^a	9 (7.2)	5 (7.7)	4 (6.7)	0.825

Table 3. Perinatal and Maternal Characteristics

Variables

Total (n = 151)

Vaginal birth (n = 73)

Cesarean section (n = 78)

P value*

^aVaginal birth (n = 5) and cesarean section (n = 4). ^bVaginal birth (n = 64) and cesarean section (n = 67). *Chi-square test with adjusted residuals, Student’s t- or Mann-Whitney test for independent samples. Significance set as P ≤ 0.05 for all analysis. UI: urinary incontinence; n: absolute frequency; n%: relative frequency; SEM: standard error of mean; P: statistical significance.

UI during pregnancy, n (n%)

Stress UI

56 (37.1)

30 (41.1)

26 (33.3)

0.324

Urge UI

37 (24.5)

19 (26.0)

18 (23.1)

0.817

Trimester of onset of UI symptoms, n (n%)

0.650

First

8 (5.3)

5 (6.8)

3 (3.8)

Second

7 (4.6)

3 (4.1)

4 (5.1)

Third

55 (36.4)

29 (39.7)

26 (33.3)

Birth weight, mean ± SEM, g

3,164.4 ± 226.4

3,081.2 ± 51.0

3,034.6 ± 80.7

0.626

Urethral diameter (level of the bladder neck)^b, mean ± SEM, mm

5.3 ± 0.6

5.6 ± 0.2

4.3 ± 0.2

≤ 0.0001

Urethral diameter (level of the median urethra), mean ± SEM, mm

5.6 ± 0.5

6.4 ± 0.2

6.6 ± 0.2

0.505

UI 6 months after birth, n (n%)^a

9 (7.2)

5 (7.7)

4 (6.7)

0.825

**Table 4.** Correlations Among Studied Factors
Variables	Urethral diameter (level of the bladder neck)	Urethral diameter (level of the median urethra)	No UI during pregnancy	No UI 6 months after birth
*Spearman’s correlation test. Significance set as P ≤ 0.05 for all analysis. n: absolute frequency; n%: relative frequency; UI: urinary incontinence; BMI: body mass index; SEM: standard error of mean; r_s: Spearman’s rho correlation coefficient; P: statistical significance.
Urethral diameter (level of the bladder neck)	1.000	1.000	0.279	0.001	-0.073	0.409	-0.077	0.425
Urethral diameter (level of the median urethra)	0.279	0.001	1.000	1.000	0.148	0.070	0.219	0.014
No UI during pregnancy	-0.073	0.409	0.148	0.070	1.000	1.000	0.214	0.016
No UI 6 months after birth	-0.077	0.425	0.219	0.014	0.214	0.016	1.000	1.000
Age	-0.344	≤ 0.0001	0.054	0.507	0.005	0.947	0.042	0.641
Height	-0.045	0.609	-0.034	0.676	-0.164	0.044	0.018	0.845
Initial gestational weight	-0.207	0.017	0.070	0.391	0.001	0.993	0.004	0.966
Final gestational weight	-0.190	0.029	0.055	0.502	-0.058	0.481	0.002	0.985
Final gestational BMI	-0.178	0.042	0.082	0.317	0.013	0.875	-0.010	0.913
Gestational weight gain	0.001	0.989	-0.016	0.849	-0.111	0.177	0.011	0.902
Previous pregnancies	-0.223	0.011	0.045	0.584	-0.015	0.852	-0.078	0.390
No urinary tract infection during pregnancy	0.166	0.058	0.021	0.796	0.080	0.331	0.129	0.150
No diabetes mellitus	0.025	0.773	-0.165	0.042	-0.066	0.422	-0.078	0.390
No systemic arterial hypertension	0.269	0.002	0.028	0.730	0.029	0.728	0.160	0.074
Trimester of onset of UI symptoms	-0.092	0.297	0.166	0.041	0.967	≤ 0.0001	0.273	0.002
Birth weight	-0.064	0.465	0.139	0.088	-0.097	0.235	-0.024	0.787

Table 4. Correlations Among Studied Factors

Variables

Urethral diameter (level of the bladder neck)

Urethral diameter (level of the median urethra)

No UI during pregnancy

No UI 6 months after birth

r_s

P value*

r_s

P value*

r_s

P value*

r_s

P value*

*Spearman’s correlation test. Significance set as P ≤ 0.05 for all analysis. n: absolute frequency; n%: relative frequency; UI: urinary incontinence; BMI: body mass index; SEM: standard error of mean; r_s: Spearman’s rho correlation coefficient; P: statistical significance.

Urethral diameter (level of the bladder neck)

1.000

0.279

0.001

-0.073

0.409

-0.077

0.425

Urethral diameter (level of the median urethra)

0.279

0.001

1.000

0.148

0.070

0.219

0.014

No UI during pregnancy

-0.073

0.409

0.148

0.070

1.000

0.214

0.016

No UI 6 months after birth

-0.077

0.425

0.219

0.014

0.214

0.016

1.000

Age

-0.344

≤ 0.0001

0.054

0.507

0.005

0.947

0.042

0.641

Height

-0.045

0.609

-0.034

0.676

-0.164

0.044

0.018

0.845

Initial gestational weight

-0.207

0.017

0.070

0.391

0.001

0.993

0.004

0.966

Final gestational weight

-0.190

0.029

0.055

0.502

-0.058

0.481

0.002

0.985

Final gestational BMI

-0.178

0.042

0.082

0.317

0.013

0.875

-0.010

0.913

Gestational weight gain

0.001

0.989

-0.016

0.849

-0.111

0.177

0.011

0.902

Previous pregnancies

-0.223

0.011

0.045

0.584

-0.015

0.852

-0.078

0.390

No urinary tract infection during pregnancy

0.166

0.058

0.021

0.796

0.080

0.331

0.129

0.150

No diabetes mellitus

0.025

0.773

-0.165

0.042

-0.066

0.422

-0.078

0.390

No systemic arterial hypertension

0.269

0.002

0.028

0.730

0.029

0.728

0.160

0.074

Trimester of onset of UI symptoms

-0.092

0.297

0.166

0.041

0.967

≤ 0.0001

0.273

0.002

Birth weight

-0.064

0.465

0.139

0.088

-0.097

0.235

-0.024

0.787