The impact of maternal body mass index on the rate of obstetric anal sphincter injury in nulliparous women: A Victorian retrospective cohort study.

BACKGROUND: Maternal obesity is an important comorbidity in contemporary obstetrics practice and is associated with significantly increased perinatal complications. Obstetric anal sphincter injury (OASIS) sustained during labour can lead to faecal incontinence, chronic pain and effects on quality of life. Currently, it is unclear if maternal body mass index (BMI) influences the risk of sustaining OASIS. AIM: To investigate the impact of increased BMI on the rate of OASIS among nulliparous women. MATERIALS AND METHODS: A retrospective cohort study was conducted, which included nulliparous women with singleton, vaginal deliveries ≥37 weeks gestation at a Victorian regional centre between 2007 and 2017 (n = 3335). Logistic regression was performed to calculate unadjusted and adjusted odds ratios (aOR). Women were grouped by World Health Organization BMI categories, and the rates of OASIS were evaluated. RESULTS: Women with a BMI ≥ 25 were significantly less likely to develop OASIS compared to women with a BMI < 25 (aOR 0.60, 95% CI 0.41-0.89). Women with a BMI ≥ 35 had significantly decreased odds of OASIS compared to normal weight women (aOR 0.27, 0.10-0.78). While not statistically significant, the odds of OASIS decreased with each increase in BMI class. Other statistically significant risk factors were maternal age, birth weight, forceps delivery, non-smokers (aOR 4.03, 1.46-11.1) and diabetes mellitus (aOR 9.48, 2.1-41.4). CONCLUSION: Women with a BMI ≥ 25 were less likely to sustain OASIS compared to women with a BMI < 25. Furthermore, the odds of OASIS decreased for each increase in BMI category. These findings warrant further investigation into the mechanism of this protective effect.

Venous thromboembolism during pregnancy and the post-partum period: incidence and risk factors in a large Victorian health service.

BACKGROUND: There is a strong recommendation for post-partum thromboprophylaxis following emergency caesarean sections, particularly in overweight women, and following prolonged labour. AIMS: To analyse the incidence and epidemiological factors associated with antepartum and post-partum venous thromboembolism in a large Victorian health service. METHODS: A retrospective study of all 6987 women delivering at Ballarat Health Services between March 1999 and June 2006. Case notes of women with confirmed venous thromboembolism during this period were subjected to detailed analysis. The data were analysed for possible risk factors, the timing of thromboembolism in relation to the pregnancy and any correlation with thromboprophylaxis, if administered. RESULTS: The rate of venous thromboembolism was 1.14 per 1000 deliveries, with risk factors of age > 30 (100%), obesity (75%), previous history of thromboembolism (62.5%) and caesarean section (37.5%). Majority of cases were diagnosed in first trimester (62.5%), and in the right lower limb (75%). None of the patients had been given thromboprophylaxis. CONCLUSION: While the incidence and risk factors were similar to those generally quoted, a much higher incidence was found in early pregnancy, and in the right lower limb. The importance of meticulous screening for risk factors in early pregnancy cannot be overemphasised.