Gestational weight gain during pregnancy is the risk factor for Omicron infection: a retrospective case-control study.

Background: It remains unclear whether gestational weight gain (GWG) during pregnancy is associated with Omicron infection in pregnant women.

Objective: To investigate whether gestational weight gain during pregnancy is associated with an increased risk of Omicron infection.

Methods: This is a retrospective case-control study of pregnant women from The Third Affiliated Hospital of Sun Yat-sen University from December 1 to 31, 2022. Pregnant women infected with Omicron were compared to those uninfected using chi-square statistics for categorical variables and t-tests or ANOVA for continuous variables. Multivariable logistic regression, along with subgroup analyses, was used to investigate the association between gestational weight gain during pregnancy and Omicron infection.

Results: Our study included 369 pregnant women who met the eligibility criteria. The proportion of pregnant women in the term, infected and uninfected with Omicron was 113(30.6%) and 256(69.4%). Classified pregnant women according to GWG during pregnancy, GWG during pregnancy above IOM was significantly associated with an increased risk of Omicron infection (P = 0.006). After adjusting for demographic factors and pregnancy complications, this association was particularly notable (OR = 2.55, 95%CI = 1.35-4.85, P = 0.004). Classified pregnant women according to pregestational BMI, in normal-weight pregnant women, GWG during pregnancy above IOM was significantly associated with an increased risk of Omicron infection (P = 0.01). After adjusting for demographic factors and pregnancy complications, this association was particularly notable (OR = 2.56, 95%CI = 1.24-5.31, P = 0.01).

Conclusion: Among women with normal weight, gestational weight gain during pregnancy above IOM was an independent risk factor for Omicron infection.