Open Access Highly Accessed Research article

Contribution of prepregnancy body mass index and gestational weight gain to caesarean birth in Canada

Susie Dzakpasu1*, John Fahey2, Russell S Kirby3, Suzanne C Tough4, Beverley Chalmers5, Maureen I Heaman6, Sharon Bartholomew1, Anne Biringer7, Elizabeth K Darling8, Lily S Lee9 and Sarah D McDonald10

Author Affiliations

1 Maternal and Infant Health Section, Surveillance and Analysis Division, Public Health Agency of Canada, 785 Carling Avenue, 6804A 4th Floor, Ottawa, ON K1A 0K9, Canada

2 Reproductive Care Program of Nova Scotia, Halifax Professional Centre, Suite 700, 5991 Spring Garden Road, Halifax, NS B3H 1Y6, Canada

3 Department of Community and Family Health, College of Public Health, University of South Florida, Bruce B. Downs Blvd. MDC 56, Tampa, FL 13201, USA

4 Departments of Paediatrics and Community Health Sciences, Faculty of Medicine, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada

5 Department of Obstetrics and Gynaecology, Ottawa Hospital Research Institute, University of Ottawa, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada

6 Faculty of Nursing, Helen Glass Centre for Nursing, University of Manitoba, 89 Curry Place, Winnipeg, MB R3T 2N2, Canada

7 Department of Family and Community Medicine, Mount Sinai Hospital, University of Toronto, Queen’s Park, Toronto, ON M5S 2C5, Canada

8 Midwifery Education Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada

9 Perinatal Services British Columbia, Provincial Health Services Authority, 3rd Floor West Tower, 555 West 12th Ave, Vancouver, BC V5Z 3X7, Canada

10 Departments of Obstetrics & Gynecology, Radiology, and Clinical Epidemiology & Biostatistics, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada

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BMC Pregnancy and Childbirth 2014, 14:106  doi:10.1186/1471-2393-14-106

Published: 18 March 2014



Overweight and obese women are known to be at increased risk of caesarean birth. This study estimates the contribution of prepregnancy body mass index (BMI) and gestational weight gain (GWG) to caesarean births in Canada.


We analyzed data from women in the Canadian Maternity Experiences Survey who had a singleton term live birth in 2005-2006. Adjusted odds ratios for caesarean birth across BMI and GWG groups were derived, separately for nulliparous women and parous women with and without a prior caesarean. Population attributable fractions of caesarean births associated with above normal BMI and excess GWG were calculated.


The overall caesarean birth rate was 25.7%. Among nulliparous and parous women without a previous caesarean birth, rates in obese women were 45.1% and 9.7% respectively, and rates in women who gained above their recommended GWG were 33.5% and 8.0% respectively. Caesarean birth was more strongly associated with BMI than with GWG. However, due to the high prevalence of excess GWG (48.8%), the proportion of caesareans associated with above normal BMI and excess GWG was similar [10.1% (95% CI: 9.9-10.2) and 10.9% (95% CI: 10.7-11.1) respectively]. Overall, one in five (20.2%, 95% CI: 20.0-20.4) caesarean births was associated with above normal BMI or excess GWG.


Overweight and obese BMI and above recommended GWG are significantly associated with caesarean birth in singleton term pregnancies in Canada. Strategies to reduce caesarean births must include measures to prevent overweight and obese BMI prior to conception and promote recommended weight gain throughout pregnancy.

Population attributable fractions; Maternal weight; Caesarean section