Association between first-trimester non-obstetric surgery during pregnancy and adverse neonatal outcomes: A retrospective observational study using a Japanese claims database

Non-obstetric surgery is commonly performed during pregnancy; however, surgery during pregnancy, particularly in the first trimester, is generally recommended to be avoided whenever possible. The association between non-obstetric surgery during the first trimester of pregnancy and adverse neonatal outcomes, including miscarriage, stillbirth, preterm birth, major congenital malformations, and low birth weight, remains unclear, and available evidence is limited. We aimed to investigate the association between non-obstetric surgery during the first trimester of pregnancy and major congenital malformations, preterm birth, and low birth weight using a large administrative database in Japan. We conducted a retrospective observational study using the JMDC Claims Database (Tokyo, Japan) from 2005 to 2023. The study population included mothers and their live-born children. Adverse outcomes were compared between children born to mothers who underwent non-obstetric surgery during the first trimester (exposed group) and those born to mothers who did not undergo non-obstetric surgery during pregnancy (comparison group) using multivariable logistic regression analyses with multiple imputation for missing covariates. The outcomes of interest were major congenital malformations, preterm birth, and low birth weight. Among 228,881 children born from 226,249 pregnancies included in the final analysis, 286 children were born from 278 pregnancies in which mothers underwent non-obstetric surgery during the first trimester. Major congenital malformations occurred in 4.2% (12/286) and 4.3% (9,807/228,063) of the exposed and comparison groups, respectively (adjusted odds ratio [aOR] 0.85, 95% CI 0.48–1.53). Preterm birth occurred in 7.3% (21/286) and 4.0% (9,092/228,063) of the exposed and comparison groups, respectively (aOR 1.41, 95% CI 0.86–2.32), while low birth weight occurred in 9.1% (26/286) and 6.3% (14,306/228,063) of the exposed and comparison groups, respectively (aOR 1.08, 95% CI 0.69–1.70). In this Japanese study, non-obstetric surgery during the first trimester of pregnancy was not significantly associated with increased risks of major congenital malformations, preterm birth, or low birth weight. These results may support informed, shared decision-making and help minimize delays in accessing necessary medical care during pregnancy.