The gestational period can modify urinary tract function. Urinary incontinence (UI) can occur in pregnancy impacting the daily activities and quality of life. 
Our objective is to describe the prevalence of UI and the possible risk factors in first trimester of first pregnancy in women.

Case-control study which included low risk pregnant women. Inclusion criteria were first pregnancy, acceptance to participate. Exclusion criteria were previous pelvic surgery, previous pelvic radiation and initial evaluation after 12 weeks of pregnancy. All patients were submitted to urogynecological exam including Pelvic Organ Prolapse Quantification (POP-Q), voiding diary and International Consultation on Incontinence Questionnaire- Short Form (ICIQ-SF).

Sixty-five patients were invited to participate of the study and three were exclude (declined the invitation), 62 first pregnancy women were evaluated, mean age was 24,9 ± 6,5 years, Body Mass Index (BMI) of 28,1± 7,8 kg/m2, mean daily voiding frequency 8,5 ± 3,5 and mean nocturia 2,2 ± 2,0 micturitions. The percentage of smokers was 8,2% and 5,1% used hygienic pads for urinary symptoms every day. There was no patient who had significant pelvic organ prolapse (POP-Q stage >1) and all pregnant women recognized the pelvic floor muscles in the digital exam. According to pelvic floor strenght scale of International Continence Society, 47,5% presented weak contractions, 40,7 % normal and 11,9 % presented strong contractions. The prevalence of UI in the studied group was 9,7%. In the univariate analysis, there was a tendency to significance for the tobacco as a risk factor for UI, 40,0% tobacco users vs 7,7% no-tobacco users (p= 0,07). There wasn’t statistic significance in relation of the others variables investigated. Between the patients with urinary losses, the mean ICIQ-SF score was 11,5 ± 5,2 (maximum score ICIQ-SF: 21) that characterizes moderate urinary incontinence, 50% shown stress incontinence, 33,3 % mixed incontinence and 17,7 shown urge incontinence. Fifth percent needs to use pads and 33,3% had the Empty Supine Stress Test (ESST) positive, compatible with severe UI.

The prevalence of UI in first pregnancy women in the first-trimester of pregnancy was 9,7%. From those whit incontinence, 33,3% exhibited severe UI according to ESST. Smoking was identified as a risk factor for this dysfunction, what is one more motive to discourage the habit in pregnancy.

This data demonstrate the necessary improvement of knowledge and treatment for this condition that can severely disturb the pregnant quality health. The inclusion of more patients in the study could help to enhance the data and found new information. Continuous follow-up of pregnants is necessary to identify UI that appears in the other periods of gestation, being the evaluation of treatments for UI during pregnancy the aims of future studies.