Pregnancy and delivery are important risk factors in the development of urinary incontinence (UI) [1]. The prevalence of UI in pregnancy and its relation to experienced inconvenience vary throughout reports. However, meta-analyses on this topic are lacking. Therefore, we performed a systematic review and meta-analysis on the prevalence of UI in pregnancy in the general population for relevant subgroups (type of UI (stress, urgency, mixed and unexplained urinary incontinence) , parity and trimester of pregnancy) and the relation to experienced inconvenience (quality of life, bother).

We performed a systematic review and meta-analysis of observational studies reporting on the prevalence of UI during pregnancy and experienced inconvenience. All women, regardless of weeks of gestation and type of UI presented in all settings were of interest. We searched the databases of MEDLINE, PubMed, Embase and CINAHL. All included articles were reference checked. The research protocol was published in the PROSPERO database (registration number 111991). Studies published between January 1, 1998 and October 1, 2018 in Dutch, English, Portuguese, German and French were included. 
Titles and/or abstracts of studies retrieved using the search strategy and those from additional sources were screened independently by two reviewers. Full text of potentially eligible studies were retrieved and independently assessed for eligibility by two review team members. Any disagreement on eligibility was resolved through discussion with a third reviewer. 
To assess the risk of bias, the Joanna Briggs critical appraisal tool for studies reporting prevalence data was used [2]. No cut-off score for low or high risk of bias is determined, as not all criteria are equally weighted. Two reviewers extracted data independently; inconsistencies were identified and resolved through discussion including a third author if necessary. 
Outcome measures are overall UI prevalence, UI prevalence by and type of UI, (stress, urgency, mixed and unexplained urinary incontinence) and experienced inconvenience. STATA Statistical Software, release15, was used for analysis. Meta-analysis was performed using random effects and heterogeneity was assessed using the I2 value.

In total 1339 references were identified. A total of 48 articles, published between 1998 and 2018 and of heterogeneous origin, were included. 
Twelve studies reported prevalence numbers by trimester only. The remaining 36 studies involving a total of 83.184 women were used to calculate the overall prevalence of UI. Preliminary results show that the mean (unweighted) prevalence of UI during pregnancy is 40% (SE 2.8, 95% CI 34.3-45.6), regardless of trimester, parity or type of UI.
Experienced inconvenience was reported in 15 studies. Although measured in various ways, most studies show that UI in pregnancy is regarded by affected women as minor problem.

Preliminary results of this extensive systematic review show that UI during pregnancy is highly prevalent. Nonetheless, most women experience UI during pregnancy only as minor problem. This might affect the felt necessity to seek professional therapy. 
Further results on (weighted) UI prevalence figures per trimester, parity, type of UI and experienced inconvenience, may further detail the moment and magnitude of felt bother throughout gestation. 
Outcomes were measured in different ways and at different times. By either validated or self-constructed questionnaires or interviews, during or after pregnancy. The definition of UI is not given in all studies. The variation in prevalence numbers might be due to heterogeneous study methodology (sample variation, symptom identification) or methodological quality [3]. The use of validated questionnaires and terminology in future research is advisable in order to improve validity of outcomes.

Preliminary results show high prevalence of UI amongst pregnant women, but in most cases with only minor experienced inconvenience. Further analyses will provide us in-depth knowledge on (weighted) UI prevalence figures per type of UI, parity and trimester of pregnancy.

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