Experiences of violence before and during pregnancy and adverse pregnancy outcomes: an analysis of the Canadian Maternity Experiences Survey.

Background: Abuse and violence against women constitute a global public health problem and are particularly important among women of reproductive age. The literature is not conclusive regarding the impact of violence against pregnant women on adverse pregnancy outcomes, such as preterm birth, small for gestational age and postpartum depression. Most studies have been conducted on relatively small samples of high-risk women. Our objective was to investigate what dimensions of violence against pregnant women were associated with preterm birth, small for gestational age and postpartum depression in a nationally representative sample of Canadian women.

Methods: We analysed data of the Maternity Experiences Survey, a nationally representative survey of Canadian women giving birth in 2006. The comprehensive questionnaire included a 19-item section to collect information on different dimensions of abuse and violence, such as type, frequency, timing and perpetrator of violence. The survey design is a stratified simple random sample from the 2006 Canadian Census sampling frame. Participants were 6,421 biological mothers (78% response rate) 15 years and older who gave birth to a singleton live birth and lived with their infant at the time of the survey. Logistic regression was used to compute Odds Ratios. Survey weights were used to obtain point estimates and 95% confidence intervals were obtained with the jacknife method of variance estimation. Covariate control was informed by use of directed acyclic graphs.

Results: No statistically significant associations were found for preterm birth or small for gestational age, after adjustment. Most dimensions of violence were associated with postpartum depression, particularly the combination of threats and physical violence starting before and continuing during pregnancy (Adjusted Odds Ratio = 4.1, 95% confidence interval: 1.9, 8.9) and perpetrated by the partner (4.3: 2.1, 8.7).

Conclusions: Our findings provide weak evidence of an association between experiences of abuse before and during pregnancy and preterm birth and small for gestational age but they indicate that several dimensions of abuse and violence are consistently associated with postpartum depression.