Pregnancy Status Is Associated with Lower Hemoglobin A1c among Nondiabetes Women in the United States from NHANES 2005–2016

BACKGROUND: It has been verified that the incidence rate of diabetes mellitus (DM) is sharply increased in pregnant female adults. However, the relationship between pregnant status and hemoglobin A1c (HbA1c) in nondiabetes women remains unclear. METHODS: We conducted a cross-sectional study of 7762 participants in the National Health and Nutrition Examination Survey (NHANES) 2005–2016. Multivariable linear regression models were performed to evaluate the associations between pregnant status with HbA1c and serum glucose in nondiabetes women. RESULTS: HbA1c was significantly lower in the pregnant group than in the nonpregnant group. There was a negative association between urine pregnancy test and HbA1c in all three models (model 1: β = −0.23, 95% CI: (−0.18 to −0.27); model 2: β = −0.20, 95% CI: (−0.15 to −0.24); model 3: β = −0.24, 95% CI: (−0.20 to −0.29)). In the subgroup analysis stratified by age, this negative association existed in all age subgroups (age <20: β = −0.20, 95% CI: (−0.04 to −0.27); age ≥20, <35: β = −0.24, 95% CI: (−0.20 to −0.29); age ≥35: β = −0.28, 95% CI: (−0.17, −0.39)). In the subgroup analysis stratified by race, the negative associations steadily existed in different subgroups (Mexican American:β = −0.20, 95% CI:(-0.11 to -0.29); Other Hispanic:β = -0.31, 95% CI: (-0.16 to -0.46); Non-Hispanic White: β = −0.24, 95% CI: (−0.17 to −0.31); Non-Hispanic Black: β = −0.21, 95% CI: (−0.12 to −0.31); Other races:β = −0.22, 95% CI: (−0.08 to −0.35)). On the other hand, a negative association between self-reported pregnant status and HbA1c was also found (model 1: β = −0.22, 95% CI: (−0.18 to −0.27); model 2: β = −0.19, 95% CI: (−0.15 to −0.2); model 3: β = −0.23, 95% CI: (−0.19 to −0.28)). In the subgroup analysis stratified by age, this negative association also existed in all age subgroups. CONCLUSIONS: The study indicated that nondiabetes women with pregnant status had significantly lower HbA1c compared with those nonpregnant. Moreover, the negative associations between pregnant status and HbA1c steadily existed in subgroups stratified by age and gender.