Pelvic Floor Support and Symptoms 1 Year Postpartum in Relation to Excess Body Habitus Before, During and After First Vaginal Birth.

Importance: Obesity may be a modifiable risk factor for pelvic floor disorders.

Objectives: The objective of this study is to determine associations between weight, weight changes, and cumulative exposure to excess body mass index (BMI) from prepregnancy to 1 year postpartum on pelvic floor support and symptoms 1 year after first vaginal birth.

Study design: In 645 primiparous women who gave birth vaginally, we assessed anatomic pelvic floor support, pelvic floor symptoms and BMI at the third trimester, 5 - 10 weeks, and 1 year postpartum; we also assessed BMI prepregnancy and predelivery. Using multivariable models, we determined associations between pelvic floor outcomes 1 year postpartum and BMI quartiles at different timepoints, gestational weight gain, and postpartum weight retention. We evaluated associations between stress urinary incontinence (SUI) and moderate/severe urinary incontinence (UI) 1 year postpartum and cumulative excess BMI from prepregnancy to 1-year postpartum (BMI1year).

Results: Body mass index was not associated with anatomic support, composite symptom burden, overactive bladder, anal incontinence, or constipation at any timepoint. Gestational weight gain and postpartum weight retention were not associated with any 1-year outcome. Body mass index at every timepoint was positively associated with SUI and moderate/severe UI; BMI1year was most predictive. Cumulative excess BMI was positively associated with SUI and moderate/severe UI but only slightly more predictive of these outcomes than BMI1year alone.

Conclusions: Body mass index over the pregnancy trajectory was not associated with outcomes other than UI. The small advantage of cumulative exposure to excess BMI over BMI1year in predicting SUI and moderate/severe UI suggests that BMI1year adequately captures risk of these 1-year outcomes.