Increasing maternal BMI linked to higher risk for postpartum infection

Key takeaways:

• Women with obesity had an increased endometritis risk after vaginal delivery and increased wound infection risk after cesarean delivery.
• Women with obesity had a lower breast abscess risk vs. normal weight.

Researchers observed a dose-dependent relationship between increasing maternal BMI and higher postpartum infection risk after different delivery modes, according to findings published in The Journal of Maternal-Fetal & Neonatal Medicine.

“The mode of delivery seems to be associated with different risks of postpartum infection. ... If the mode of delivery affects, not only the risk of mastitis, but also the risk of developing a postpartum breast abscess is more sparsely described,” Daniel Axelsson, MD, from the department of obstetrics and gynecology at Ryhov County Hospital and the department of biomedical and clinical sciences at Linköping University, Sweden, and colleagues wrote. “Furthermore, the impact of maternal body composition on the potential risk of breast abscess related to the mode of delivery is, to the best of our knowledge, not earlier described.”

Axelsson and colleagues conducted a large population-based observational study with data from 841,780 women who had singleton deliveries recorded in three Swedish Medical Birth Registers from 2005 to 2012. Researchers defined outcomes by ICD-10 codes given within 8 weeks postpartum.

Overall, 2.6% of women had an ICD-10 code suggestive of postpartum infection during the first 8 weeks postpartum: 1.5% had endometritis, 0.5% had wound infection and 0.7% had breast abscess. In addition, 9.3% of other deliveries were associated with either another infection diagnosis or a dispensed prescription drug with a code suggestive of infection. In the study, 11% of women had obesity class II and 3.3% had obesity class III.

Researchers observed a dose-dependent relationship between increasing maternal BMI and higher risks for postpartum infections. Compared with women with normal weight, those with obesity classes II and III had an increased endometritis risk following vaginal delivery (adjusted OR = 1.45; 95% CI, 1.29-1.63) and increased risk for wound infections after cesarean delivery (aOR = 3.83; 95% CI, 3.39-4.32). Researchers noted no difference in how maternal BMI affected associations between cesarean delivery and wound infection, regardless of planned or emergent delivery.

Women with obesity classes II and III had lower breast abscess risks compared with women with normal weight (aOR = 0.47; 95% CI, 0.38-0.58). Endometritis risk following labor induction and wound infection risk in women with an obstetrical sphincter injury decreased as maternal BMI increased.

According to the researchers, further studies on this subject should stratify for breastfeeding as those data were not available for this study group.

“This data could have made it possible to draw further conclusions on the effect of BMI on the risk of breast abscess after childbirth,” the researchers wrote.