A case–control study of clinical characteristics and risk factors of symptomatic postpartum pubic symphysis diastasis

Postpartum pubic symphysis diastasis (PPSD) refers to the separation of pubic symphysis after delivery. It is typically diagnosed based on clinical symptoms and radiologic findings. This study tried to assess clinical characteristics and risk factors of PPSD. This was a nested case–control study matched for year of delivery and gestational age at delivery using a retrospective cohort of women who delivered vaginally at a single institution. The incidence of PPSD was 0.156% (33/21,131). The incidence rate increased from 0.08% (7/9328) in 2000–2004 to 0.13% (9/7138) in 2005–2009 and to 0.36% (17/4665) in 2010–2016, simultaneously with an increase of maternal age (30.7 ± 3.5 years in 2000–2004 to 31.8 ± 3.8 years in 2005–2009 and 32.8 ± 3.8 years in 2010–2016). Nulliparity was associated with a higher incidence of PPSD (81.8% in cases vs. 57.6% in controls, p = 0.01). Other factors including pre-pregnancy body mass index, weight gain during pregnancy, gestational diabetes, induction of labor, duration of labor, epidural anesthesia, vacuum-assisted delivery, episiotomy, neonatal sex and birth weight failed to show difference between the two groups. In short, the incidence of PPSD increased with time along with an increase of maternal age. Nulliparity was the only significant risk factor for PPSD.