To investigate effects of macrosomia on the incidence of early pelvic floor dysfunction (PFD) in puerperae.

A total of 301 primiparae who had full-term pregnancy and vaginal delivery, and evaluated the pelvic floor function after 6-8 weeks postpartum from March to December 2014 in Affliated Hospital of Hubei University of Medicine, Xiangyang No.1 People′s Hospital, were chosen as research subjects. According to birth weight of newborns, they were divided into study group (n=145, macrosomia delivery, birth weight ≥4 000 g) and control group (n=156, normal weight fetus delivery, 3 000 g≤ birth weight<4 000 g). The general clinical data, the proportion of normal pelvic floor muscle strength, fatigue degree and vaginal dynamic pressure, incidence rates of postpartum stress urinary incontinence (SUI) and pelvic organ prolapse (POP), and the results of maternal perineal ultrasonography were all statistically compared between two groups of puerperae by independent-samples t test or chi-square test. The study protocol was approved by the Ethics Committee of Affliated Hospital of Hubei University of Medicine, Xiangyang No.1 People′s Hospital, and informed consents were obtained and signed by participants.

① There were no significant differences between two groups of puerperae in general clinical data such as maternal age, body mass index before pregnancy, incidence rates of prolonged labor and perineal episiotomy, family monthly income, etc. (P>0.05). ②The proportions of normal pelvic floor typeⅠ and Ⅱ muscle fibers strength of puerperae were 9.7% and 11.0% in study group, and 19.2% and 21.2% in control group, respectively; The proportions of normal pelvic floor type Ⅰ and Ⅱ muscle fibers fatigue degrees of puerperae were 15.9% and 11.7% in study group, and 30.8% and 26.3% in control group, respectively; The proportions of normal vaginal dynamic pressure of puerperae were 31.0% in study group and 81.4% in control group, respectively. The above mentioned proportions of indexes of puerperae in study group were all lower than those in control group, and all the differences were statistically significant (χ²=5.521, P=0.019; χ²=5.646, P=0.017; χ²=9.265, P=0.002; χ²=10.238, P=0.001; χ²=77.873, P<0.001). ③The incidence rates of SUI, anterior and posterior vaginal walls prolapse of puerperae in study group (9.0%, 27.6%, 25.5%) were all higher than those in control group (2.6%, 11.5%, 10.3%), and the differences were statistically significant (χ²=5.779, P=0.016; χ²=12.441, P<0.001; χ²=12.064, P=0.001). ④The results of perineal ultrasonography in 38 cases of puerperae in study group and 40 cases of puerperae in control group showed that incidence rates of POP, the distance of downward dislocation of bladder neck and urethral metastatic angle during Valsalva movement, and the levator ani muscle hole area during calm state, anal contraction and Valsalva movements in study group [68.4%, (28.4±5.8) mm, (46.2±16.3)°, (15.1±3.5) mm^2, (13.6±1.6) mm^2, (22.9±5.2) mm²] were all higher, wider or larger than those in control group [40.0%, (6.4±4.4) mm, (19.3±13.2)°, (12.9±3.4) mm^2, (11.1±2.3) mm², (14.3±2.8) mm²], and the differences were statistically significant (χ²=6.334, P=0.012; t=18.930, P<0.001; t=8.029, P<0.001; t=2.816, P=0.006; t=5.545, P<0.001; t=9.157, P<0.001).

Macrosomia can reduce pelvic floor muscle strength and vaginal dynamic pressure of puerperae, increase muscle fatigue degree, which resulting in SUI and POP in postpartum. Mild PFD and injuries of levator ani muscle should be detected by postpartum three dimensional ultrasonography.