**3.1 Incidence of urinary incontinence postpartum**

Prevalence of UI postpartum is a so called "mixed bag" of incident UI before pregnancy, incident UI in pregnancy and incident UI postpartum (Iosif, 1981, Nygaard, 2006). Risk factors for incident UI at the different time points vary. Mode of delivery; vaginal delivery, vacuum and forceps, are risk factors for incident UI postpartum compared to cesarean section (Glazener et al., 2006). Incident UI is also called *de novo UI* or *new onset UI*.

Cross-sectional studies on incident UI postpartum must rely on maternal recall of UI status during pregnancy. Several large cross-sectional studies have data on incident UI postpartum. A large population-based cross-sectional study from USA investigated incidence of UI postpartum among 5,599 primiparous women (Boyles et al., 2009). The incidence of UI 6 months postpartum was 10 %. About 25 % of the study population had delivered by cesarean section, which might explain the low incidence. Glazener et al published in 2006 cross-sectional data on incident UI in pregnancy among 3,405 primiparous women with mean age of 25 years (Glazener et al., 2006). They found an incidence of UI 3 months postpartum of 15 %. Wilson used questionnaires to investigate incident UI postpartum among 1,505 women who were resident in the Dunedin area, New Zealand (Wilson et al., 1996). The incidence of UI 3 months postpartum was 12 % and 21 % among primiparous and parous women, respectively.

Prospective data on incident UI among 595 primiparous Canadian women 6 months postpartum by a validated questionnaire showed an incidence of any UI of 26 % (Farrell et al., 2001). The use of a research nurse to clarify and complete the questionnaire with each participant might explain the high incidence. Several Scandinavian cohort studies have reported incidence of UI postpartum; in the 30 year old Swedish cohort of 1,411 primiparous women, 19 % reported incident stress UI 6 months post partum (Iosif, 1981). Wesnes et al found a similar incidence of any UI 6 months postpartum (21 %) among 12,679 primiparous women who were continent before pregnancy (Wesnes et al., 2009). Eliasson found an identical incidence of UI 12 months postpartum among 665 Swedish primiparous women (Eliasson et al., 2005). In a smaller Danish cohort of 305 primiparous women Viktrup et al found an incidence of stress UI of 7 % 3 months after vaginal delivery (Viktrup et al., 1992).

Mode of delivery affects the incidence estimates, as study populations with high CS rate is likely to report lower incidence of UI postpartum. Prolonged pressure from baby's head and trauma as baby passes through the vaginal canal may affect the pelvic floor and urethral support. These mechanisms are likely to be involved in incident UI postpartum. The reported incidence of UI among primiparous and parous women postpartum varies between 0 – 26 % and 4 – 21 %, respectively (Table 3). The majority of reported incident UI postpartum are in the range of 5 – 21 % among primiparous women, and 8 – 15 % among parous women. No systematic review on incident UI postpartum has been identified. In a review on the association between CS on UI postpartum Nygaard reported the range of incident UI postpartum to be 7 – 15 % among all women (Nygaard, 2006). For women who become incontinent postpartum, not many women achieve spontaneous continence during the first postpartum year (Thom & Rortveit, 2010)


Prevalence of UI postpartum is a so called "mixed bag" of incident UI before pregnancy, incident UI in pregnancy and incident UI postpartum (Iosif, 1981, Nygaard, 2006). Risk factors for incident UI at the different time points vary. Mode of delivery; vaginal delivery, vacuum and forceps, are risk factors for incident UI postpartum compared to cesarean

Cross-sectional studies on incident UI postpartum must rely on maternal recall of UI status during pregnancy. Several large cross-sectional studies have data on incident UI postpartum. A large population-based cross-sectional study from USA investigated incidence of UI postpartum among 5,599 primiparous women (Boyles et al., 2009). The incidence of UI 6 months postpartum was 10 %. About 25 % of the study population had delivered by cesarean section, which might explain the low incidence. Glazener et al published in 2006 cross-sectional data on incident UI in pregnancy among 3,405 primiparous women with mean age of 25 years (Glazener et al., 2006). They found an incidence of UI 3 months postpartum of 15 %. Wilson used questionnaires to investigate incident UI postpartum among 1,505 women who were resident in the Dunedin area, New Zealand (Wilson et al., 1996). The incidence of UI 3 months postpartum was 12 % and 21 %

Prospective data on incident UI among 595 primiparous Canadian women 6 months postpartum by a validated questionnaire showed an incidence of any UI of 26 % (Farrell et al., 2001). The use of a research nurse to clarify and complete the questionnaire with each participant might explain the high incidence. Several Scandinavian cohort studies have reported incidence of UI postpartum; in the 30 year old Swedish cohort of 1,411 primiparous women, 19 % reported incident stress UI 6 months post partum (Iosif, 1981). Wesnes et al found a similar incidence of any UI 6 months postpartum (21 %) among 12,679 primiparous women who were continent before pregnancy (Wesnes et al., 2009). Eliasson found an identical incidence of UI 12 months postpartum among 665 Swedish primiparous women (Eliasson et al., 2005). In a smaller Danish cohort of 305 primiparous women Viktrup et al found an incidence of stress UI of 7 % 3 months after vaginal

Mode of delivery affects the incidence estimates, as study populations with high CS rate is likely to report lower incidence of UI postpartum. Prolonged pressure from baby's head and trauma as baby passes through the vaginal canal may affect the pelvic floor and urethral support. These mechanisms are likely to be involved in incident UI postpartum. The reported incidence of UI among primiparous and parous women postpartum varies between 0 – 26 % and 4 – 21 %, respectively (Table 3). The majority of reported incident UI postpartum are in the range of 5 – 21 % among primiparous women, and 8 – 15 % among parous women. No systematic review on incident UI postpartum has been identified. In a review on the association between CS on UI postpartum Nygaard reported the range of incident UI postpartum to be 7 – 15 % among all women (Nygaard, 2006). For women who become incontinent postpartum, not many women achieve spontaneous continence during

section (Glazener et al., 2006). Incident UI is also called *de novo UI* or *new onset UI*.

**3. Urinary incontinence postpartum** 

**3.1 Incidence of urinary incontinence postpartum** 

among primiparous and parous women, respectively.

delivery (Viktrup et al., 1992).

the first postpartum year (Thom & Rortveit, 2010)


Cross-s = cross sectional study, Ex. = examination, Quest. = questionnaire, Interv. = interview, PP = postpartum, (s) = stress UI, (u) = urgency UI, mth = month.

Table 3. Incidence of urinary incontinence postpartum by parity.

Epidemiology of Urinary Incontinence in Pregnancy and Postpartum 29

Norway Cross-S 40 Quest. 6 weeks 29 %(s)

**PP Primi-parous Parous** 

**Author, year Origin Design N Data collection Time of UI** 

(Bo & Backe-Hansen,

2007)

(Altman et al., 2006) Sweden Cohort 304 Quest. 5 mth 15 % (s) (Arrue et al., 2010) Spain Cohort 396 Ex., interv. 6 mth 15 % (Baydock et al., 2009) Canada Cross-S 632 Interv. 4 mth 23 %

(Boyles et al., 2009) USA Cross-S 5,599 Quest. 6 mth 17 % (Burgio et al., 2003) USA Cohort 523 Interv. 6 mth 11 % (Chaliha et al., 2002) England Cohort 161 Quest., urodyn 3 mth 30 % (Chaliha et al., 1999) England Cohort 549 Interv- 3 mth 15 % (Diez-Itza et al., 2010) Spain Cohort 352 Ex., quest. 12 mth 11 % (s) (Dimpfl et al., 1992) Germany Cross-S 350 Interv. 3 mth 6 % (s) (Dolan et al., 2004) UK Cohort 492 Quest. 3 mth 13 % (Eason et al., 2004) Canada Cohort 949 Quest. 3 mth 31 % (Ege et al., 2008) Turkey Cross-S 1,749 Quest. 12 mth 20 % (Ekstrom et al., 2008) Sweden Cohort 389 Quest. 3 mth 13% (s), 4%(u) (Eliasson et al., 2005) Sweden Cohort 665 Quest. 12 mth 49 % (Ewings et al., 2005) England Cohort 723 Quest. 6 mth 45 % (Farrell et al., 2001) Canada Cohort 595 Quest. 6 mth 26 % (Foldspang et al., 2004). Denmark Cross-S 1,232 Quest. > 12 mth 26 % (Francis, 1960) England Cohort 400 Ex, interv. 3 mth 24 % 29 % (s) (Glazener et al., 2006) UK, N.Z. Cross-S 3,405 Quest. 3 mth 29 % (Hatem et al., 2005) Canada Cross-S 2,492 Quest 6 mth 30 % (Hvidman et al., 2003) Denmark Cross-S 642 Quest. 3 mth 3 % (Jundt et al, 2010) Germany Cohort 112 Quest, ex. 6 mth 21 % (Iosif, 1981) Sweden Cohort 1,411 Quest. 6-12 mth 22 % (s) (King & Freeman, 1998) UK Cohort 103 Ex, interv. 3 mth 22 % (Mason et al., 1999) England Cohort 717 Quest. 3 mth 10 % (s) 31 % (s) (Morkved & Bo, 1999) Norway Cross-S 144 Ex., interv. 2 mth 38 % (Pregazzi et al., 2002) Italy Cross-S 537 Ex., interv. 3 mth 8 % 20 % (Raza-Khan et al., 2006) USA Cohort 113 Quest. Postpartum 46 % 43 % (Sampselle et al., 1996) USA Cohort 59 Quest., ex. 6 mth 67 % (s) (Schytt et al., 2004) Sweden Cohort 2,390 Quest. 12 mth 18 % (s) 24 % (s) (Serati et al., 2008) Italy Cohort 336 Interv. 6/12 mth 27/23 %

(Stanton et al., 1980) UK Cohort 189 Interv. 3 mth 6 % (s), 8% (u) (Thomason et al., 2007) USA Cross-S 121 Ex., interv. 6 mth 45 % [Thompson 2002] Australia Cohort 1,295 Quest. 6 mth 18 % (Torrisi et al., 2007) Italy Cohort 562 Ex., interv. 3 mth 11 % (s) (Viktrup et al., 1992) Denmark Cohort 305 Interv. 3 mth 7 % (s) (Wesnes et al., 2009) Norway Cohort 12,679 Quest. 6 mth 31 % (Wijma et al., 2003) Netherland Cohort 117 Quest., ex. 6 mth 15 % (Wilson et al., 1996) N.Z Cross-S 1,505 Quest. 3 mth 29 % 34 % (Yang et al, 2010) China cross-s 1,889 Quest. 6 mth 10 %

cross-s = cross sectional study, Ex. = examination, PP = postpartum, (s) = stress UI, (u) = urgency UI,

Table 4. Prevalence of urinary incontinence postpartum by parity.

Urodyn = urodynamic testing, mth = months

### **3.2 Prevalence of urinary incontinence postpartum**

Vaginal delivery is an important and well documented risk factor for UI postpartum, also when compared with cesarean section. If a woman delivers by caesarean section only, a protective effect on UI compared with vaginal delivery is documented 12 years after delivery (MacArthur et al., 2011). The population based cross sectional EPINCONT study found that women aged 50– 64 years who had delivered by cesarean section or vaginal only had similar UI prevalence, suggesting that any protection from caesarean section might be lost with advancing age (Rortveit et al., 2003).

UI after delivery may affect women for the rest of their lives. Several studies have presented data on the long term prognoses of UI postpartum. Farrell found that prevalence of UI did not change from 6 weeks postpartum to 6 months postpartum (Farrell et al., 2001). A six year follow up study concluded that 24 % of the women had persisting UI from 3 months postpartum to 6 years postpartum (MacArthur et al., 2006). A 12 year prospective study indicates that onset of UI in pregnancy or postpartum increased the risk for UI 12 years later (Viktrup et al., 2006). A systematic review found only small changes in prevalence of UI over the first year postpartum (Thom & Rortveit, 2010). As prevalence figures of UI postpartum appear to be stable, time point of data collection postpartum may be of less importance. We will therefore limit our presentation to studies investigating prevalence of UI during the first year postpartum.

A large questionnaire based cross-sectional study of 5,599 primiparous American women investigated prevalence of UI postpartum (Boyles et al., 2009). The prevalence of any UI was 17 % 6 months postpartum. A similar questionnaire based cross-sectional study was performed in Turkey (Ege et al., 2008). One year postpartum 20 % of the parous women had UI. Stress and mixed UI were most common types of UI.

A large cohort study on 2,390 Swedish women recruited in pregnancy assessed stress UI at 2 and 12 months postpartum by questionnaire (Schytt et al., 2004). UI was defined as any UI last week. Data was linked to the Swedish birth registry. The authors found that 18 % of primiparous women and 24 % of multiparous women had stress UI 12 months postpartum. The largest study (by 2011) on UI during pregnancy and postpartum found a prevalence of UI of 31 % among 12,679 primiparous women 6 months postpartum. All the participants were continent before pregnancy (Wesnes et al., 2009).

There is a wide range of reported prevalences of any UI among primiparous women (6 – 67 %) and parous women (3 – 45 %) (Table 4). The majority of the studies report however estimates 15 – 31 % and 18 – 38 % among primiparous and parous women, respectively. This corresponds well with reports from several reviews on UI postpartum. In a review on UI and its precipitating factors postpartum Herbruck reported prevalences of stress UI of 22 – 33 % postpartum among all women (Herbruck, 2008). The ICI epidemiology report presented prevalence of 15 – 30 % among all women the 1. year postpartum (Milsom et al., 2009). In a review Nygaard reported the prevalence of UI postpartum to be 9 – 31 % among all women (Nygaard, 2006). Authors of a systematic review reported a pooled prevalence of UI of 29 % and 33 % 3 months postpartum among primiparous and parous women, respectively (Thom & Rortveit, 2010).

Vaginal delivery is an important and well documented risk factor for UI postpartum, also when compared with cesarean section. If a woman delivers by caesarean section only, a protective effect on UI compared with vaginal delivery is documented 12 years after delivery (MacArthur et al., 2011). The population based cross sectional EPINCONT study found that women aged 50– 64 years who had delivered by cesarean section or vaginal only had similar UI prevalence, suggesting that any protection from caesarean section might be

UI after delivery may affect women for the rest of their lives. Several studies have presented data on the long term prognoses of UI postpartum. Farrell found that prevalence of UI did not change from 6 weeks postpartum to 6 months postpartum (Farrell et al., 2001). A six year follow up study concluded that 24 % of the women had persisting UI from 3 months postpartum to 6 years postpartum (MacArthur et al., 2006). A 12 year prospective study indicates that onset of UI in pregnancy or postpartum increased the risk for UI 12 years later (Viktrup et al., 2006). A systematic review found only small changes in prevalence of UI over the first year postpartum (Thom & Rortveit, 2010). As prevalence figures of UI postpartum appear to be stable, time point of data collection postpartum may be of less importance. We will therefore limit our presentation to studies investigating prevalence of

A large questionnaire based cross-sectional study of 5,599 primiparous American women investigated prevalence of UI postpartum (Boyles et al., 2009). The prevalence of any UI was 17 % 6 months postpartum. A similar questionnaire based cross-sectional study was performed in Turkey (Ege et al., 2008). One year postpartum 20 % of the parous women had

A large cohort study on 2,390 Swedish women recruited in pregnancy assessed stress UI at 2 and 12 months postpartum by questionnaire (Schytt et al., 2004). UI was defined as any UI last week. Data was linked to the Swedish birth registry. The authors found that 18 % of primiparous women and 24 % of multiparous women had stress UI 12 months postpartum. The largest study (by 2011) on UI during pregnancy and postpartum found a prevalence of UI of 31 % among 12,679 primiparous women 6 months postpartum. All the participants

There is a wide range of reported prevalences of any UI among primiparous women (6 – 67 %) and parous women (3 – 45 %) (Table 4). The majority of the studies report however estimates 15 – 31 % and 18 – 38 % among primiparous and parous women, respectively. This corresponds well with reports from several reviews on UI postpartum. In a review on UI and its precipitating factors postpartum Herbruck reported prevalences of stress UI of 22 – 33 % postpartum among all women (Herbruck, 2008). The ICI epidemiology report presented prevalence of 15 – 30 % among all women the 1. year postpartum (Milsom et al., 2009). In a review Nygaard reported the prevalence of UI postpartum to be 9 – 31 % among all women (Nygaard, 2006). Authors of a systematic review reported a pooled prevalence of UI of 29 % and 33 % 3 months postpartum among primiparous and parous women,

**3.2 Prevalence of urinary incontinence postpartum** 

lost with advancing age (Rortveit et al., 2003).

UI during the first year postpartum.

UI. Stress and mixed UI were most common types of UI.

were continent before pregnancy (Wesnes et al., 2009).

respectively (Thom & Rortveit, 2010).


cross-s = cross sectional study, Ex. = examination, PP = postpartum, (s) = stress UI, (u) = urgency UI, Urodyn = urodynamic testing, mth = months

Table 4. Prevalence of urinary incontinence postpartum by parity.

Epidemiology of Urinary Incontinence in Pregnancy and Postpartum 31

affect her reporting of UI by improving her memory about earlier UI leading to a recall bias. Cross sectional studies have less valid incidence figures than prospective cohorts. Crosssectional studies can gather information about the prevalence of UI, but they cannot distinguish between incident and long-established UI. Therefore, cross-sectional studies can usually only measure prevalence of UI. Also, they cannot identify cause-and-effect

Timing of data collection can affect prevalence estimates of UI in pregnancy. Some studies question women about UI during each trimester, but most studies question women at one certain time point in pregnancy (Brown et al., 2010, Lewicky-Gaupp et al., 2008) or just after birth (Sottner et al., 2006). Some studies do not report what time in pregnancy the women reported UI (Sharma et al., 2009). As prevalence of UI increases in pregnancy, the time of information gathering will affect the prevalence estimates of UI during pregnancy. When it comes to data collection postpartum, some studies report on UI at 6 - 9 weeks postpartum (D'Alfonso et al., 2006, Lewicky-Gaupp et al., 2008, Meyer et al., 1998), 3 months (Eason et al., 2004, Hannah et al., 2002), 4 months (Baydock et al., 2009), 6 months (Thomason et al., 2007), 12 months (Serati et al., 2008) or > 12 months (Foldspang et al., 2004, Fritel et al., 2004) postpartum. The time of information gathering postpartum might affect incidence and prevalence estimates of UI. However, a recent review indicates that prevalence of UI is stable first year postpartum (Thom & Rortveit, 2010), and time of data collection postpartum

Permanence, frequency and volume are used by authors as threshold to define women with UI in association with pregnancy. Permanence or duration can be defined as one or more episodes of UI in the previous month (Brown et al., 2010, Wilson et al., 1996). Some authors use longer periods, like trimesters (Schytt et al., 2004) or the 6 months postpartum period (Schytt et al., 2004). Some authors investigate severe UI defined by weekly or daily leakage (Al-Mehaisen et al., 2009) while others do not report any cut-off (van Brummen et al., 2006). Prevalence estimates are lower for daily UI compared to weekly or monthly UI (Thom, 1998). Some studies have a cut-off for minimum frequency, amount or severity of UI for women to be included in the study as incontinent. A high cut-off decreases the number of women who fulfil the UI criteria in a study. Differing thresholds may explain differing

Stress UI predominates in young women. Stress UI is more common in pregnancy and postpartum than urgency UI and mixed UI. Also, the incidence of pure urgency UI in pregnancy or postpartum is low compared with incidence of stress UI and mixed UI. The prevalence of pure stress UI is reported to be 2 – 8 times higher than the prevalence of pure urgency UI in pregnancy (Brown et al., 2010, Goldberg et al., 2005, Raza-Khan et al., 2006). Prevalence of mixed UI is reported to be 0.3 – 1.5 times of the prevalence of pure stress UI in pregnancy (Brown et al., 2010, Goldberg et al., 2005, Raza-Khan et al., 2006). The

relationships as exposure and outcome information are gathered at the same time.

**4.4 Timing of data collection** 

may therefore be of less importance.

incidence and prevalence estimates of UI.

**4.5 Threshold** 

**4.6 Type of UI** 
