Preventing urinary incontinence during pregnancy and ... - Springer Link

Int Urogynecol J (2013) 24:889–899 DOI 10.1007/s00192-012-2017-3

REVIEW ARTICLE

Preventing urinary incontinence during pregnancy and postpartum: a review Stian Langeland Wesnes & Gunnar Lose

Received: 26 October 2012 / Accepted: 1 December 2012 / Published online: 23 February 2013 # The International Urogynecological Association 2013

Abstract Urinary incontinence (UI) is a common condition in association with pregnancy. Incident UI in pregnancy or postpartum are significant risk factors for UI later in life. Epidemiological studies on UI during pregnancy and postpartum list numerous variables associated with UI. For women, the main focus is on pelvic floor muscle training to prevent UI. However, several other modifiable risk factors are likely to contribute to prevention of UI during pregnancy and postpartum. This review investigated modifiable risk factors for UI during pregnancy and postpartum and also reviewed randomized controlled trials on prevention of UI in association with pregnancy. Systematic searches for publications until September 2012 on prevention of UI during pregnancy and postpartum were performed. Based on available evidence, the following recommendations to prevent UI during pregnancy and postpartum were made: women should be advised not to smoke before or during pregnancy (grade B), aim at normal weight before pregnancy (grade B), and aim at regaining prepregnancy weight postpartum (grade B). Occasional lowintensity training should be advocated (grade B), and constipation should be avoided during pregnancy (grade B) and postpartum (grade C). Women should be advised to perform pelvic floor muscle training during pregnancy and

A related article can be found at doi:10.1007/s00192-013-2061-7. S. L. Wesnes (*) Research Group for General Practice, Department of Public Health and Primary Health Care, University of Bergen, Kalfarveien 31, 5018 Bergen, Norway e-mail: [email protected] G. Lose Department of Obstetrics and Gynecology, Copenhagen University, Hospital Herlev, Herlev, Denmark e-mail: [email protected]

postpartum (grade A) and to use perineal warm packs during delivery (grade B). Cesarean section to prevent UI cannot be recommended (grade D). If lifestyle recommendations are addressed in association with pregnancy, incidence of UI during pregnancy and postpartum is likely to decrease. Keywords Urinary incontinence . Pregnancy . Prevention . Review

Introduction Urinary incontinence (UI) is a common condition in association with pregnancy. Epidemiological studies on UI during pregnancy and postpartum list numerous variables associated with UI. Some risk factors like race, chronic diseases, and fetal size are not modifiable risk factors. However, several risk factors are modifiable and might be promoted to prevent UI in association with pregnancy. UI is common in association with pregnancy A large proportion of women experience new onset of UI during pregnancy (17–54 %). Prevalence estimates during pregnancy are reported to be 35–67 %. The incidence and prevalence of UI postpartum are also high, with estimates of 5–21 % and 15–45 %, respectively [1]. A recent systematic review estimated pooled prevalence of UI postpartum to be 31 % [2]. Prevention is beneficial About 65 % of all women with UI during their life report that their UI started up either in pregnancy or postpartum [3]. Odds ratios (OR) for UI postpartum among women who were incontinent compared to women who were continent in

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Int Urogynecol J (2013) 24:889–899

pregnancy vary from 1.7 [4] to 7.8 [5] during the 3- to 12month postpartum period. Incident UI postpartum is also a risk factor for UI even 12 years after delivery [6]. As UI is a highly prevalent condition in association with pregnancy, primary prevention strategies are likely to have clinically significant impact on UI postpartum and later in life. This review will look into modifiable risk factors for UI during pregnancy and postpartum and also review randomized controlled trials (RCT) on prevention of UI in association with pregnancy. Ways to prevent UI in pregnancy and postpartum will be summarized.

Table 1 Level of evidence

Materials and methods

Results

The source publications for this review are intended as an adequate, but not complete sample of studies on modifiable risk factors for UI in association with pregnancy. Systematic searches were done using MEDLINE up to August 2012 with the terms “urinary incontinence” and “pregnancy” or “postpartum” in addition to one single term at the time representing a modifiable risk factor or preventive factor. The following terms were used: age, body mass index (BMI), weight, constipation, smoking, coffee, mode of delivery, cesarean section (CS), vacuum, forceps, ventouse, assisted vaginal delivery, instrumental delivery, crossed legs, pelvic floor muscle training (PFMT), bladder training, perineal massage, exercise, epidural, second phase, episiotomy, rupture, perineal warm pack, vaginal cones, electrical stimulation, and weight loss. Searches were also done in the Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews. There was no attempt to search gray literature (conferences, abstracts, theses, and unpublished trials). All identified papers were first reviewed by title. Thereafter, abstracts were read; finally, full-text articles that gave information on modifiable factors in pregnancy or postpartum were read. When recommendations were based on a limited number of articles (≤4), a checklist using the Consolidated Standards of Reporting Trials (CONSORT) or Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) were used to ensure reporting and quality of the articles. Results were categorized according to time point for prevention: before pregnancy, during pregnancy, or postpartum. Unfortunately, there were not many RCTs on prevention of UI during pregnancy or postpartum. However, there were many cohort studies and cross-sectional studies of high quality. Although well-conducted RCTs provide uniquely useful evidence, evidence from other types of studies is also critically important for making evidence-based recommendations. Studies in this review were graded from 1 to 4 based upon International Consultation on Urological Diseases’

Actions before pregnancy

Level

Quality of evidence for recommendations

1

Meta-analysis of trials or at least one RCT with clinical endpoints Low-quality RCT and good-quality cohort studies Good-quality case-control studies or case series Expert opinion based on other evidence

2 3 4

main steps for grading evidence [7] (Table 1). Recommendations are based upon available evidence [7] (Table 2).

Smoking Smoking can cause UI through coughing and increased bladder pressure when coughing. Hannestad et al. found a significantly increased risk of UI among nonpregnant female former and current heavy smokers compared to women who had never smoked [8]. No RCT study was identified. A cohort study of 523 American women found that smoking before pregnancy compared to not smoking gave the highest independent risk for UI postpartum in multivariable analyses [OR 2.9, 95 % confidence interval (CI) 1.4–3.9] [9]. Avoiding smoking before pregnancy will reduce UI postpartum if the association between smoking and UI is true. Some level 2 evidence indicates that smoking before pregnancy represents a risk factor for UI postpartum. Women should be advised not to smoke before pregnancy (grade B). Age Women lose 1 % of striated urethra muscle per year, leading to a reduction in urethral pressure [10]. Age at first delivery has increased during recent decades. Prevalence of UI Table 2 Level of recommendations Grade

Basis for recommendations

Recommendation

A

Consistent level 1 evidence or great body of consistent level 2 evidence Consistent level 2 or 3 evidence

Required, should always be followed

B

C D

Level 4 evidence Inadequate evidence, conflicting evidence, or consistent evidence not in favor of intervention

Recommended, should usually be followed Optional No recommendation possible


increases throughout women’s fertile period of life [11]. Maternal age is found to be an independent risk factor for UI during pregnancy and postpartum in >20 prospective studies. A review published in 2011 concluded that advanced maternal age was an independent strong risk factor for UI postpartum; however, results from long-term studies were unclear [12]. In most studies referred to in the review, age >35 years at pregnancy gave an OR in the range of 1.0– 2.5 for UI postpartum. There is sufficient level 2 evidence to conclude that high maternal age is associated with increased prevalence of UI during pregnancy and postpartum. However, the public and personal consequences of pregnancy at a young age preclude a grade A recommendation of first pregnancy at a young age to prevent UI. Overweight In the USA, 26 % of women aged 20–39 are overweight, and 29 % are obese [13]. Being overweight is believed to cause UI through increased intra-abdominal pressure, increased intravesical pressure, stretching and weakening of the pelvic floor, and increased urethral mobility. RCT studies on weight reduction have found significant effects on improved UI. No RCT study on weight and UI in association with pregnancy was identified. More than 20 cohort studies report an association between being overweight before pregnancy and UI during pregnancy and postpartum [4, 14]. Burgio et al. found an OR for UI of 1.2 (95 % CI 1.1– 1.4) per 5 kg/m2 increase in BMI [14]. This is in line with risk estimates in other studies. Brown et al. also reported increased incidence of UI in pregnancy by increasing BMI before pregnancy [15]. There is consistent level 2 evidence on the association between being overweight before pregnancy and UI during pregnancy. Thus, women should strive to achieve normal weight before pregnancy (grade A). Actions during pregnancy

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be associated with incident UI [17, 19]. There is level 2 evidence to recommend pregnant women to avoid constipation to prevent UI (grade B). Smoking Prevalence studies indicate that 20–50 % of pregnant women smoke in the beginning of pregnancy [20]. We did not identify any RCT studies on smoking cessation and UI during pregnancy. Results from epidemiological studies on smoking and UI in pregnancy are not consistent. A Danish cross-sectional study of 7,700 pregnant women showed in adjusted analyses that women who smoked in week 16 of pregnancy had an OR of 1.3 (95 % CI 1.0–6.0) for incident UI in pregnancy compared to nonsmokers [21]. A cohort study on 1,501 Taiwanese primiparous women found that smoking compared to nonsmoking in pregnancy increased the risk of incident urge UI (OR 2.0, 95 % CI 1.1–3.5), but not stress UI [22]. Several cohort studies have found no association between smoking in pregnancy and UI [4, 23], and two studies even found that smoking in pregnancy had a protective effect on UI 3 months postpartum [24]. Due to the inconsistency of level 2–3 evidence in the literature regarding smoking and UI, it is difficult to give evidence-based recommendations (grade D). Caffeine In the Norwegian Mother and Child Cohort Study (MoBa), 100,000 pregnant women were enrolled in week 16 in pregnancy and followed up for several years after birth. The average woman in this study drank 1.2 cups of coffee per day in week 16 of pregnancy. A review concluded that there is sufficient evidence to support caffeine reduction/elimination in nonpregnant women to improve overactive bladder [25]. We were not able to identify quality studies investigating the association between caffeine intake and UI in pregnancy. There is insufficient scientific evidence to recommend caffeine reduction in association with pregnancy (grade D).

Constipation Crossed legs In an Irish study of 7,000 pregnant women, 40 % had constipation at some stage during pregnancy [16]. It is believed that stool in the rectum may hinder bladder emptying, leading to detrusor instability. Prolonged pushing during defecation might affect the nervus pudendus. A large Chinese cohort study with 10,098 women enrolled ≥ week 28 found constipation to be a risk factor for stress UI during pregnancy (OR 1.3, 95 % CI 1.1–1.4) and 6 months postpartum (OR 1.6, 95 % CI 1.3–1.9) [17]. The association with constipation compared to non-constipation and UI in pregnancy was also found to give an OR of 4.2 (95 % CI 1.7–9.9) in a cross-sectional study [18] and 1.8 (95 % CI 1.0–3.3) in a cohort study [19]. Constipation is also found to

Norton et al. did a study on 65 women who leaked when coughing [26]. The study reported significantly less leakage when coughing with crossed legs compared to coughing in a standing position. The effect of crossed legs has never been investigated in association with pregnancy. Therefore, there is no evidence to support a recommendation of coughing with crossed legs in pregnancy to prevent UI (grade D). Bladder training Bladder training focuses on regaining continence, while prompted voiding, habit retraining, and timed voiding aim

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to avoid UI. A systematic review found bladder training to be efficient in preventing UI in a general nonpregnant population [27]. No evidence is available on the effect of bladder training on UI in pregnancy; therefore, a recommendation on bladder training to prevent UI in pregnancy cannot be made (grade D). Physical activity Among 34,000 pregnant women in the MoBa study, 28 and 20 % did regular physical exercise in weeks 17 and 30, respectively [28]. High-intensity physical activity like running and jumping is associated with stress UI in pregnancy, but not necessarily the cause of stress UI [29]. Some studies have also found inactivity in pregnancy to be associated with UI. An RCT investigated the effect of exercise on prevention of UI in pregnancy [30]. Women in the intervention group received a standardized exercise program three times per week or more during the 12-week intervention period, including aerobic activity and strength training (including specific PFMT). Both groups received detailed information about PFMT. Significantly less women in the intervention group reported incident stress UI ≥1 per week (p=0.03). Any UI was not significantly different, indicating that exercise in combination with PFMT might be beneficial in pregnancy. One large cohort study found occasional training (exercise once or twice per week) to be associated with reduced risk of UI in pregnancy compared to frequent training (OR 0.7, 95 % CI 0.7–0.8) [17]. A Swedish cohort study was designed to investigate the effect of physical exercise during pregnancy on UI [31]. Pregnant women who did low-intensity training (prevalence of UI 60 %) had less UI compared to women who did high-intensity training (prevalence of UI 64 %) or women who were inactive (prevalence of UI 63 %) during pregnancy. Based upon limited level 1 and 2 evidence regarding physical activity and prevention of UI, low-intensity training a few times per week can be recommended to avoid UI (grade B). Pelvic floor muscle training PFMT is the preventive intervention for UI in pregnancy with the most RCT evidence. PFMT is regarded as first-line treatment and prevention of UI in association with pregnancy. In the MoBa study, 28 % of the women did PFMT in week 30 of pregnancy. PFMT acts on UI by increasing resting tone and by improving the ability to produce fast and powerful muscle contractions when coughing. PFMT increases intraurethral pressure, immobilizes the urethra, and thereby prevents urethral descent. The ability of the pelvic floor to mechanically compress the urethra against the symphysis improves and thereby prevents UI [32, 33].


Mason et al. did an RCT on antenatal PFMT in prevention of UI postpartum. The intervention group reported less UI compared to the control group both in week 36 of pregnancy and 3 months postpartum; however, results were not significantly different [34]. The authors commented that a proportion of the women in the intervention group did not attend all PFMT classes, and few exercised PFMT according to instructions during pregnancy, which may explain the nonsignificant findings. This comment represents a fundamental problem in studies on PFMT; the outcome of PFMT is closely linked to a dose-response relationship of PFMT. Intensive training with close follow-up is necessary to achieve beneficial effects [35]. PFMT is found to be efficient when performed with 8–12 maximal pelvic floor muscle contractions, holding the contraction for 6–8 seconds with three additional fast contractions at the end of each maximal pelvic floor muscle contraction. PFMT should be done twice daily for 3 months. Best results are found when a physiotherapist gives instructed lessons in PFMT and controls for correct performance [36]. The single-blind RCT study using the above training methods in primiparous women found a prevalence of UI in week 36 of pregnancy of 32 % in the training group and 48 % in the control group (p=0.007). They concluded that PFMT prevented UI in pregnancy in one of six women [36]. A Cochrane review from 2009 found PFMT during pregnancy among women who were continent before pregnancy to significantly prevent UI in week 34 of pregnancy, with a risk ratio of 0.44 (95 % CI 0.30–0.65) [37]. PFMT during pregnancy was also found to prevent UI postpartum with a risk ratio of 0.71 (95 % CI 0.52–0.97). Based on level 1 evidence, PFMT should be recommended to women during pregnancy to prevent UI in pregnancy (grade A). Restricted weight gain According to the Institute of Medicine recommendations for weight gain during pregnancy, a normal weight woman should gain 11.5–16 kg during pregnancy [38]. In the MoBa study, average weight gain during pregnancy among 12,679 primiparous women who had normal BMI before pregnancy was 15.9 kg [39]. Assumptions have been made in the “Epidemiology of urinary and faecal incontinence and pelvic organ prolapse” report about weight gain during pregnancy being the main contributor to the increased incidence of UI during pregnancy [40], but there is no scientific evidence for this. More than ten studies have looked into the association between weight gain and UI during pregnancy and postpartum. The majority did not find any association between weight gain in pregnancy and UI during pregnancy or postpartum. Only one study was primarily designed to investigate this hypothesis; no clear association


was found [39]. A weak association between weight gain >90th percentile in the first trimester and UI in week 30 of pregnancy was identified, but weight gain in the first trimester did not predict UI postpartum. Weight gain >90th percentile during pregnancy was not a risk factor for UI postpartum (OR 1.0, 95 % CI 0.9–1.1). On the basis of level 2 and 3 evidence, high weight gain in pregnancy is not associated with UI. Restricted weight gain in pregnancy to prevent UI should not be recommended (grade D). Perineal massage Perineal massage in pregnancy reduces the incidence of perineal tears [41], probably by increasing elasticity in perineal tissue before delivery. RCT studies have not found a protective effect in the perineal massage group compared to the control group regarding UI postpartum [41, 42]. A Cochrane review confirms these findings, reporting a risk ratio of 0.92 (95 % CI 0.71–1.20) [43]. There is level 1 evidence to claim that perineal massage in pregnancy does not prevent UI postpartum. Perineal massage to avoid UI cannot be recommended (grade D). Actions in association with delivery and postpartum Pushing during second stage of labor The second phase of birth is the active period of birth when contractions occur. In an RCT study, the intervention group was coached to push hard with each contraction. The control group did not get such information. The intervention group had significantly more pelvic trauma and pelvic problems 3 months postpartum compared to women in the control group; however, UI was not investigated [44]. One RCT randomized 249 women to routine care with coached pushing or spontaneous self-directed pushing. Spontaneous pushing did not lead to reduced UI 12 months postpartum [42]. One cohort study isolated the effect of pushing in the second stage by only investigating women delivering by CS. Women who delivered by planned CS were the reference group. Women delivering by CS in the second stage of labor without pushing had an OR of 0.9 (95 % CI 0.5–1.7) for UI postpartum. Women delivering by CS in the second stage of labor after active pushing had an OR of 1.0 for UI (95 % CI 0.5–1.6) [45]. Inconsistent level 1, 2, and 3 evidence indicates that active pushing during the second stage of labor does not appear to be associated with UI postpartum (grade D), and recommendations can therefore not be made. Prolonged second stage of labor There are discrepancies in cohort studies reporting data on prolonged second stage and UI. Several studies have found

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an association between prolonged second stage of labor and UI postpartum [46–48]. A cohort of 1,507 primiparous women who were continent before pregnancy found prolonged second stage to be associated with an adjusted increased risk of postpartum UI in women with vaginal delivery (OR 1.9, 95 % CI 1.1–3.4) [47]. A recent cohort study found that only prolonged second stage in association with assisted vaginal delivery was associated with increased risk of UI [49]. In contrast, two large observational studies did not find an association between prolonged second stage and UI postpartum [4, 9]. There is too much inconsistent level 2 and 3 evidence to conclude upon the effect of prolonged second stage on UI. Recommendations cannot be made (grade D). Epidural Epidural is a common form of analgesia, as approximately 23 % of all Norwegian women have an epidural during delivery. Epidural analgesia appears to be associated with prolonged labor, urinary retention, higher rates of instrumental delivery, and CS [50]. Results regarding the association between epidural analgesia and UI postpartum are inconsistent. No RCT was identified. A cross-sectional study of 11,397 women with vaginal delivery found epidural analgesia to be associated with stress UI (OR 1.2, 95 % CI 1.0–1.5) [51]. Several studies have found no association between epidural analgesia and UI postpartum; a study of 583 nulliparous women investigated the effect of epidural analgesia on postpartum stress UI. Women who received an epidural had a similar incidence of postpartum stress UI compared to women who did not receive an epidural [50]. These findings are in line with results in multivariate analyses in several other cohort studies [19, 52–54]. A review from 2002 concluded that epidural analgesia might be associated with UI immediately postpartum, but not 3–12 months postpartum [55]. Based on level 2 evidence, there is inconsistency in the literature and uncertainty regarding the effect of epidural analgesia on UI in the short and long term as well as uncertainties regarding mechanisms of epidural analgesia to lead to UI postpartum. Restriction of epidural analgesia to prevent UI postpartum cannot be recommended (grade D). Episiotomy Episiotomy rates vary from 10 % in Sweden, about 30 % in Europe, 33 % in the USA to 100 % in Taiwan [56]. Episiotomy represents a trauma to the pelvis, and this might lead to UI postpartum. We identified 12 epidemiological studies investigating the association between episiotomy and UI. In six studies, episiotomy was a risk factor for UI postpartum, while contrary findings were found in the remaining six

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studies. In a Cochrane review from 2009, restrictive episiotomy compared to routine episiotomy was found to be associated with fewer traumas and less suturing after delivery [57]. However, in line with other reviews [58], the Cochrane review did not find that episiotomy increased the risk of UI postpartum (risk ratio 0.98, 95 % CI 0.79–1.20) [57]. Based on level 1, 2, and 3 evidence, restrictive episiotomy cannot be recommended to prevent UI postpartum (grade D). Sphincter tear Third- or fourth-degree tears are identified clinically at the time of vaginal delivery in 0.6–9 % of patients [59]. Risk factors for tears are instrumental delivery, prolonged second stage of labor, birth weight greater than 4 kg, episiotomy, epidural analgesia, and early pushing [60], which in various studies, independently, have been found to be associated with UI. It is unclear whether a tear represents an intermediate confounder or if a trauma to the pelvic floor alone leads to UI. Obviously, no RCT on sphincter tear was identified. A cross-sectional study of 2,300 women postpartum where data were linked to the Swedish birth registry gave data for tears and UI. This study found a significantly increased relative risk (RR) for UI after a first- to seconddegree tear (1.4, 95 % CI 1.2–1.7) and a nonsignificant increased RR after a third- to fourth-degree tear (1.5, 95 % CI 0.7–3.2) [61]. Prospective short-term follow-ups have not found an association between tear grade 3–4 and UI 12 months postpartum (OR 1.5, 95 % CI 0.6–3.6) [9]. Whether or not women are sutured after a second-degree tear does not affect the risk of UI postpartum [62]. There does not appear to be an association between tears and UI several years after delivery. A study of 200 Swedish women with vaginal delivery did not find any association between sphincter tear and stress UI (OR 0.9, 95 % CI 0.4– 2.2) or urgency UI (OR 0.6, 95 % CI 0.2–2.1) 10 years after delivery [63]. A prospective study did not find an increased risk of UI 18 years after sphincter tear (risk ratio 1.2, 95 % CI 0.8–1.6) [64]. Based on inconsistency and mostly negative level 2 and 3 evidence, perineal tears do not seem to be associated with UI postpartum. As perineal tears cannot be controlled, a recommendation cannot be made. Delivery position A Cochrane review regarding positions at the second stage of delivery found that any upright or lateral position, compared with supine or lithotomy positions, was associated with reduced duration of the second stage of labor, a small reduction in assisted deliveries, reduced use of episiotomy, and reduced reporting of severe pain during the second stage of labor. UI was not investigated in this context [65].


We were not able to identify any study on delivery position and UI. One Danish protocol on delivery position and UI exists, but results have not yet been published [66]. Due to a lack of scientific evidence regarding delivery position and UI, no recommendation can be made (grade D). Assisted vaginal delivery About 11 % of women in the UK deliver by assisted vaginal delivery [67]. In Norway, about 1.7 and 8 % of all women deliver by forceps and ventouse, respectively. Assisted vaginal delivery is associated with increased incidence of perineal tear and episiotomy [67]. Assisted vaginal delivery is often conducted in association with prolonged labor, macrosomia, and abnormal fetal presentation at delivery. A systematic review on instrumental delivery from 2007 included only a small number of studies. The review concluded that there was no significantly increased risk of UI after forceps or vacuum delivery [68]. However, many large cohort studies were not included or have been published after 2007. We identified 29 epidemiological studies and no RCT studies reporting data on assisted vaginal delivery and UI postpartum, of which 16 found a positive association and 13 found no association between assisted vaginal delivery and UI postpartum. In multivariate analyses in a cohort of 632 women with vaginal delivery, forceps delivery was found to be one of two risk factors for UI 4 months postpartum (RR 1.5, 95 % CI 1.1–2.1) [69]. Several cohort studies confirm these findings [45, 70, 71]. The largest cohort study so far on UI in pregnancy and postpartum (MoBa) consisted of 12,679 primiparous women who were continent before pregnancy. Among these women, 26 % became incontinent after vacuum delivery (OR 3.2, 95 % CI 2.1–4.6) and 30 % became incontinent after forceps delivery (OR 4.0, 95 % CI 2.6–5.8) compared to CS [72]. The risk was not significantly increased compared to spontaneous vaginal delivery. The second largest cohort on UI in pregnancy, based upon 3,405 primiparous women, did not find an association between forceps delivery (OR 1.2, 95 % CI 0.9–1.5) or vacuum delivery (OR 1.2, 95 % CI 0.8–1.6) and incident UI 6 months postpartum [4]. A large crosssectional study based upon 11,397 women in the EPINCONT study found in adjusted analyses no significant association between UI and forceps delivery (OR 0.9, 95 % CI 0.7–1.1) or vacuum delivery (OR 0.8, 95 % CI 0.7–1.0) [51]. Uncertainty exists regarding whether assisted vaginal delivery can be an intermediate confounder or an independent risk factor for UI postpartum. New large studies with level 2 evidence have inconsistent and mostly negative results regarding the effect of instrumental delivery on UI postpartum, and recommendations to prevent UI based on restrictive use of instrumental delivery cannot be made (grade D).


Perineal warm packs Perineal warm packs are found to relieve pain during delivery and significantly reduce the proportion of third- and fourth-degree tears after birth [73]. We identified one RCT study that investigated the effects of applying warm packs to the perineum on perineal trauma and maternal comfort. The study found that 267 women who had perineal warm packs during birth had significantly reduced prevalence of UI 3 months postpartum (9.7 %) compared to 263 women in the control group (22.4 %, p50 years. A follow-up study over 12 years found an incomplete protection of UI if deliveries were a combination of CS and subsequent vaginal deliveries (OR 1.1, 95 % CI 0.9–1.5) [83]. A Danish cohort study found a significantly reduced risk of UI 12 years after CS, independent of mode of later deliveries [6]. A follow-up study found a nonsignificant protection in adjusted analyses after CS only compared to vaginal delivery 20 years after delivery (OR 0.4, 95 % CI 0.1–2.0) [84]. The Term Breech Trial did not find a significant risk reduction of UI after CS compared to vaginal delivery 2 years after delivery (risk ratio 0.8, 95 % CI 0.6–1.1) [85]. A study found that the risk of UI after CS compared to spontaneous vaginal delivery was equal among women who were continent and incontinent during pregnancy, indicating that CS is not to be recommended as secondary prevention of UI postpartum among women who had UI during pregnancy [72]. Today, prophylactic elective CS is promoted to prevent postpartum UI without robust evidence to support this practice [3, 86, 87]. Several studies indicate that CS reduces the risk of UI in the short run, but the clinical significance of these findings remains unclear. CS does not show a clear risk reduction of UI in long-term follow-up studies. CS influences both mother’s and child’s health beyond UI. Risks involved by undergoing an elective CS should always be kept in mind before CS is performed to prevent UI. Based on level 1, 2, and 3 evidence, CS to prevent UI cannot be recommended (grade D). Pelvic floor muscle training In the MoBa study 78 % of the women did occasional PFMT and 28 % did PFMT three times per week 6 months after delivery. Two RCT studies have investigated the effect of postpartum PFMT on incident UI, both finding significantly reduced incidence of UI postpartum [88, 89]. Meyer et al. randomized women to 12 sessions of pelvic floor exercises with biofeedback and electrostimulation or no training 9 weeks postpartum. The incidence of stress UI decreased in 2 % of control subjects compared with 19 % of women who underwent pelvic floor education (p=0.002) [88]. Mørkved and Bø randomized women to a control group or an intensive PFMT program with a physiotherapist from week 8–16 postpartum. There was a significantly reduced incidence of UI at 16 weeks and 1 year postpartum among women who underwent the PFMT program [89]. There is no doubt that PFMT is efficient. Based on level 1 evidence, PFMT should be recommended postpartum to prevent UI (grade A). However, it is still unclear what type of PFMT is most efficient, or whether some women benefit more from PFMT than others.

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Vaginal cones and electrical stimulation

Discussion

Vaginal cones and electrical stimulation intend to strengthen the pelvic floor in a more efficient way than ordinary PFMT. Training with vaginal cones and electrical stimulation has documented effects in treating UI in a nonpregnant population. Several RCT studies comparing vaginal cones, electrotherapy, and PFMT to controls in nonpregnant women have found less UI in the intervention group compared to controls, but no difference in effect on UI between vaginal cones, electrotherapy, and PFMT [90, 91]. This is confirmed in a Cochrane review; there was no difference between cones and PFMT (RR 1.1, 95 % CI 0.9–1.4) or electrostimulation (RR 1.0, 95 % CI 0.9–1.1) [92]. Few studies have investigated the effect of vaginal cones [93] and electrostimulation [94] on treating UI during pregnancy or postpartum. The preventive effect has not been investigated. It is less likely that young continent women will use vaginal cones or electrical devices to prevent UI postpartum. There is a lack of evidence of the effect of vaginal cones and electrical stimulation to prevent UI in association with pregnancy. There is no reason to recommend electrical stimulation or vaginal cones in addition to PFMT (grade D).

UI is highly prevalent during pregnancy and postpartum. Preventive measures should be addressed in continence promotion during pregnancy and postpartum. This is the first review comprehensively summarizing modifiable risk factors for UI in pregnancy and postpartum with a focus on prevention, beyond RCT studies. There is clear evidence to support that PFMT can prevent UI during pregnancy and postpartum. Perineal warm packs are also found to reduce the incidence of UI postpartum. Epidemiological studies indicate that avoiding smoking and constipation in association with pregnancy, performing lowintensity training during pregnancy, having a normal BMI before pregnancy, and regaining prepregnancy weight postpartum will help to prevent UI in association with pregnancy (Table 3). Despite imaging and functional studies revealing damage to the pelvic floor during vaginal delivery, the clinical significance of these findings is unclear. We find a lack of evidence that UI in association with pregnancy is explained by obstetrical trauma. This is in line with recent reviews [96–98]. Risk reductions were not large for most associations. The effect is, however, likely to be significant due to the high prevalence of UI in association with pregnancy. If the associations found in epidemiological studies are true, reducing/ removing the modifiable risk factors will prevent UI caused by the attributed risk factor. The effect will thereby depend on how common the risk factor is among pregnant women. Smoking, constipation, and being overweight are highly common among pregnant women (20–50 %, 20–40 % and 25–50 %, respectively). Reduction of these risk factors is likely to clinically significantly prevent UI in association with pregnancy. We cannot rule out an additive effect when combining different preventive actions. The total cost of UI in the USA was US$19.5 billion in 2000 [99]. Preventive actions are likely to have large economic influence.

Weight reduction In the MoBa study normal weight women gained on average 15.8 kg during pregnancy and lost on average 14.5 kg during the 6-month postpartum period [39]. In an RCT study published in the New England Journal of Medicine weight loss among nonpregnant women was found to significantly improve frequency of UI episodes in the weight loss group compared to the control group [95]. One cohort study was designed to investigate weight loss postpartum among 12,679 primiparous women who were continent before pregnancy. Weight loss >90th percentile among women who were continent during pregnancy significantly reduced the incidence of UI 6 months postpartum compared to women with 1-50th percentile weight loss (RR 0.7, 95 % CI 0.5–0.8) [39]. Based on level 2 evidence, women should try to regain prepregnancy weight by 6 months postpartum (grade B). Constipation In a cross-sectional study on 7,700 Swedish women, 21 % had constipation 2 months postpartum. In the same study population, constipation 2 months postpartum was associated with UI 1 year postpartum (OR 1.4, CI 95 % 1.1–1.9) [61]. Based on level 3 evidence, a recommendation of avoiding constipation postpartum can be supported (grade C).

Table 3 Recommendations for avoiding UI during pregnancy and postpartum Lifestyle changes • Women should not smoke before or during pregnancy (grade B) • Women should aim at normal weight before pregnancy (grade A) and aim at regaining prepregnancy weight postpartum (grade B) • Occasional low-intensity training should be advocated (grade B) • Constipation should be avoided during pregnancy and postpartum (grade C) Pelvic floor muscle training • Women should perform PFMT during pregnancy and postpartum (grade A) Delivery • Women should have perineal warm packs during delivery (grade B)


Only a small proportion of the evidence gathered for this review is from RCT studies. Many factors like perineal tear, instrumental delivery, constipation, and weight reduction postpartum are very difficult to investigate through RCT studies. Therefore, the best available scientific evidence on these aspects will come from epidemiological studies. Many factors can be investigated through RCT studies. More research with standardized terminology, definitions, and outcome measures and high methodological quality and power to find clinical outcomes is needed to increase knowledge on prevention of UI in association with pregnancy. If our cost-efficient lifestyle recommendations become addressed by obstetricians, midwives, and general practitioners, the incidence of UI during pregnancy and postpartum is likely to decrease. Conflicts of interest Stian Langeland Wesnes: none. Gunnar Lose has been a consultant for Contura, contributed with trial participation for Pfizer, been a consultant and honorarium speaker for Astella, done research collaboration with Coloplast and contributed in workshops for Johnson & Johnson.

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