Levels of Antibodies Against Tissue Transglutaminase During Pregnancy Are Associated With Reduced Fetal Weight and Birth Weight

BACKGROUND & AIMS: Celiac disease in pregnant women has been associated with poor growth of the fetus, but little is known about how the level of celiac disease affects fetal growth or birth outcomes. We assessed the associations between levels of antibodies against tissue transglutaminase (anti-tTG, a marker of celiac disease) and fetal growth and birth outcomes for pregnant women. METHODS: We performed a population-based prospective birth cohort study of 7046 pregnant women. Serum samples were collected during the second trimester of pregnancy and analyzed for levels of anti-tTG. Based on these levels, the women were categorized into 3 groups: negative anti-tTG (<= 0.79 U/mL; n = 6702), intermediate anti-tTG (0.8 to <= 6 U/mL; n = 308), or positive anti-tTG (>6 U/mL; n = 36). Data on fetal growth and birth outcomes were collected from ultrasound measurements and medical records. RESULTS: Fetuses of women in the positive anti-tTG group weighed 16 g less than those of women in the negative anti-tTG group (95% confidence interval [CI], -32 to -1 g) during the second trimester and weighed 74 g less (95% CI, -140 to -8 g) during the third trimester. Newborns of women in the intermediate and positive anti-tTG groups weighed 53 g (95% CI, -106 to -1 g) and 159 g (95% CI, -316 to -1 g) less at birth, respectively, than those of women in the negative anti-tTG group. The reduction in birth weight in offspring of mothers in the intermediate anti-tTG group was 2-fold greater among mothers who carried HLA-DQ2 or -DQ8 than among those without HLA-DQ2 or -DQ8. CONCLUSIONS: Levels of anti-tTG in pregnant women are inversely associated with fetal growth. Growth was reduced to the greatest extent in fetuses of women with the highest levels of anti-tTG (>6 U/mL). Birth weight was also reduced in women with intermediate levels of anti-tTG (0.8 to <= 6 U/mL) and further reduced in those carrying HLA-DQ2 and -DQ8.