To evaluate the impact of breastfeeding on postpartum lower urinary tract, vaginal, and sexual function symptoms.  We hypothesized that breastfeeding women would have clinically and statistically significantly worse lower urinary tract symptoms as measured by the Urinary Distress Inventory-6 (UDI-6) at 3 months postpartum than non-breastfeeding women.  Vaginal symptoms and sexual function were evaluated as secondary outcomes.

After Institutional Review Board approval was obtained, 361 primiparous, postpartum women with singleton deliveries ≥34 weeks were surveyed regarding breastfeeding choices (breastfeeding vs non-breastfeeding) and genitourinary symptoms in this novel prospective cohort study. Validated instruments, including Urinary Distress Inventory-6 (UDI-6), Incontinence Impact Questionnaire-7 (IIQ-7), Most Bothersome Symptom questionnaire (MBS), and Pelvic Organ Prolapse Incontinence Sexual Questionnaire, IUGA-Revised (PISQ-IR), were utilized and, apart from for the paper-based baseline collection, were performed on-line. Questionnaires were completed at baseline, 6 weeks, 3 and 6 months postpartum, except the PISQ-IR, which was included at 3 and 6 months.  The primary outcome was comparing UDI-6 scores at 3 months postpartum between subjects primarily breastfeeding vs those not breastfeeding.  Secondary outcome measures included the IIQ-7, MBS and PISQ-IR scores. Two-sample t-tests and chi-square (or Fisher’s exact) tests were used for the bivariate analysis. Multivariable linear and logistic regression models were fitted to evaluate the group differences while controlling for potential confounding variables such as age, race, BMI, diabetes status, and infant weight at delivery. 74 participants were needed in each arm to achieve 80% power to detect a minimum important difference (11.6 points) in UDI-6 using a two-tailed t-test at a type I error rate of 0.05.

183 women (110 breastfeeding, 73 non-breastfeeding) met inclusion criteria. Overall the mean age of participants was 27.3±5.7, 53.6% were Caucasian, and 62.3% delivered vaginally. In bivariate analysis, UDI-6 scores at 3 months were not significantly different between the breastfeeding (5.6±11.8) and non-breastfeeding (7±12) groups, p=0.43.  Similarly, there was no difference at 6 months (5.9±9.5 breastfeeding, 8.1±13.5 non-breastfeeding, p=0.27).  IIQ-7 scores did not differ significantly between groups at 3 months (4.9±7.4 breastfeeding, 13±5 non-breastfeeding, p=0.07) or 6 months (6.9±11.6 breastfeeding, 6.7±16.1 non-breastfeeding, p=0.96). Multivariable analysis at 3 months (Table 1) revealed that breastfeeding participants who were not sexually active had significantly lower partner-related scores (β=-0.85, 95% CI=(-1.58,-0.12), p=0.024) than the non-breastfeeding group. Those in the breastfeeding group who were sexually active scored higher, however, in condition impact than those in the non-breastfeeding group (β=0.29, 95% CI=(0.11, 0.47), p=0.002). Results of the MBS revealed that breastfeeding women were almost three times more likely to experience vaginal dryness (OR=2.82, 95% CI=(1.19, 6.66), p=0.018) at 3 months.

Our primary hypothesis was that breastfeeding women would have worse lower urinary tract symptoms and impact; however, there was no difference in UDI-6 and IIQ-7 scores between women breastfeeding versus not breastfeeding at 3 and 6 months postpartum. More bothersome vaginal dryness and mixed impact on sexual function were noted in the breastfeeding group.

Breastfeeding impacts symptoms of vaginal dryness and sexual function but did not affect lower urinary tract symptoms at a clinically significant level.  These findings may lead to treatments impacting postpartum vaginal symptom improvement.