Domestic violence by a partner or ex-partner during pregnancy increases the risk of preterm birth, low birth weight and small-for-gestational-age babies, finds a study in BJOG: An International Journal of Obstetrics and Gynaecology (BJOG).

Researchers from the University of Iowa analyzed 50 studies into the effects of domestic violence by a partner or ex-partner on risk of preterm birth, low birth weight (less than 2500g) and small-for-gestational-age babies. The combined results evaluated more than 5 million women from 17 countries, 15,000 of whom had experienced domestic violence.

Overall, the results found that domestic violence doubled the risk of preterm birth and low birth weight. This risk was increased further for women who experienced two or more types of domestic violence during their pregnancy.

There were fewer studies which looked into the effect of domestic violence by a partner or ex-partner on the baby being small-for-gestational-age, however the results indicated a small increased risk.

“Domestic violence by a partner or ex-partner is of particular concern during pregnancy when not one, but two lives are at risk,” says Audrey Saftlas, UI professor of epidemiology and lead author of the study.

“Although rates of domestic violence differ across the world, the detrimental effects of abuse on pregnant women are very clear and we must continue to establish effective interventions globally in order to prevent violence and to support women who report abuse,” Saftlas says.

Domestic violence by a partner or ex-partner is one of the most common forms of violence against women and includes physical, sexual, financial, psychological or emotional abuse.

Domestic violence by a partner or ex-partner can directly affect the growing fetus, through physical or sexual trauma, or indirectly due to increased maternal stress, inadequate nutrition and poor prenatal care.

“This is a strong study bringing together data from around the world,” says Professor John Thorp, deputy editor-in-chief of BJOG.

“While it provides robust evidence about the association between domestic violence by a partner or ex-partner, violence during pregnancy and adverse infant outcomes, further research is needed to understand the biological mechanism behind this link, as well as addressing the effectiveness of interventions to prevent domestic violence during pregnancy,” Thorp added.

In addition to Saftlas, the research team at the University of Iowa included first author Brittney Donovan, doctoral student in epidemiology, Cassie Spracklen and Kelli Ryckman from the Department of Epidemiology, and Marin Schweitzer from the Department of Internal Medicine.