Third- and fourth-degree perineal tears among primiparous women in England between 2000 and 2012: time trends and risk factors.
Gurol-Urganci, I;
Cromwell, DA;
Edozien, LC;
Mahmood, TA;
Adams, EJ;
Richmond, DH;
Templeton, A;
van der Meulen, JH;
(2013)
Third- and fourth-degree perineal tears among primiparous women in England between 2000 and 2012: time trends and risk factors.
BJOG, 120 (12).
pp. 1516-1525.
ISSN 1470-0328
DOI: https://doi.org/10.1111/1471-0528.12363
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OBJECTIVE: To describe the trends of severe perineal tears in England and to investigate to what extent the changes in related risk factors could explain the observed trends. DESIGN: A retrospective cohort study of singleton deliveries from a national administrative database. SETTING: The English National Health Service between 1 April 2000 and 31 March 2012. POPULATION: A cohort of 1 035 253 primiparous women who had a singleton, term, cephalic, vaginal birth. METHODS: Multivariable logistic regression was used to estimate the impact of financial year of birth (labelled by starting year), adjusting for major risk factors. MAIN OUTCOME MEASURE: The rate of third-degree (anal sphincter is torn) or fourth-degree (anal sphincter as well as rectal mucosa are torn) perineal tears. RESULTS: The rate of reported third- or fourth-degree perineal tears tripled from 1.8 to 5.9% during the study period. The rate of episiotomy varied between 30 and 36%. An increasing proportion of ventouse deliveries (from 67.8 to 78.6%) and non-instrumental deliveries (from 15.1 to 19.1%) were assisted by an episiotomy. A higher risk of third- or fourth-degree perineal tears was associated with a maternal age above 25 years, instrumental delivery (forceps and ventouse), especially without episiotomy, Asian ethnicity, a more affluent socio-economic status, higher birthweight, and shoulder dystocia. CONCLUSIONS: Changes in major risk factors are unlikely explanations for the observed increase in the rate of third- or fourth-degree tears. The improved recognition of tears following the implementation of a standardised classification of perineal tears is the most likely explanation.