Pelvic floor biometry during a first singleton pregnancy and the relationship with symptoms of pelvic floor disorders: a prospective observational study




To assess pelvic floor biometry during pregnancy and the correlation with symptoms of pelvic floor disorders in women.


A prospective observational study.


Antenatal clinic between August 2009 and May 2011.


Nulliparous women in their first pregnancy.


Pelvic floor was assessed by translabial ultrasound and symptoms of pelvic floor disorders were explored with a standardised questionnaire at each trimester.

Main outcome measures

Pelvic floor biometry during pregnancy.


A total of 405 (91.6%) women completed the study. As the pregnancy advanced, there was significant descent of the bladder neck (BN), cervix, and anorectal junction. The hiatal area (HA) was significantly enlarged, with a mean increase of 15.1 ± 24.8% at rest, and 24.7 ± 28.5% at Valsalva, at third trimester when compared with first trimester. Risk factors for stress urinary incontinence (SUI) were: descent of BN at Valsalva (OR 3.2, 95% CI 1.2–8.5), increase in HA at pelvic floor contraction (PFMC; OR 1.3, 95% CI 1.0–1.6), and increase in maternal age (OR 1.1, 95% CI 1.0–1.2), at first trimester; increase in HA at PFMC (OR 1.3, 95% CI 1.1–1.5) at second trimester; and descent of BN at rest (OR 2.3, 95% CI 1.1–4.9) and increase in maternal age (OR 1.1, 95% CI 1.02–1.2) at third trimester. Descent of anorectal junction (OR 1.5, 95% CI 1.1–1.9) and increase in HA at rest (OR 1.2, 95% CI 1.0–1.3) were factors for prolapse symptoms at second and third trimester, respectively.


Pelvic floor changes begin during pregnancy. There was significant descent of the BN, cervix, and anorectal junction, and enlargement of the hiatal area, as the pregnancy advanced. SUI was associated with descent of the BN, and prolapse symptoms were associated with an increase in the hiatal area.