Association between Maternal Body Mass Index and Fetal Acidosis in Term Twin Pregnancies: A Retrospective Cohort Study.

OBJECTIVE: Given the increased risk of fetal acidosis in singleton neonates born to pregnant people with an elevated body mass index (BMI), our objective was to evaluate the association between pre-pregnancy/first trimester BMI and fetal acidosis among term twin pregnancies.

METHODS: Retrospective study of pregnant people with twin gestation and their term infants admitted to our centre between 2014 and 2019. Using a generalized estimating equation, the association between maternal BMI and fetal acidosis was determined using odds ratios (OR) with 95% confidence intervals (CI). A two-sided P value < 0.05 was considered significant.

RESULTS: A total of 275 pregnant people and 550 infants were analyzed. The number (%) of pregnancies in each BMI class were 10 (4%) underweight, 155 (56%) normal weight, 66 (24%) overweight, 22 (8%) class I, 9 (3%) class II, and 13 (5%) class III. The prevalence of maternal diabetes and hypertension was highest in class III (31%) and class II (44%), respectively. Fetal acidosis was diagnosed in 35 (6%) infants. After adjusting for confounders (maternal age, diabetes, and hypertension), infants born to those with elevated BMI did not have increased odds of fetal acidosis compared to those born to underweight and normal weight group [OR of 1.29 (95% CI 0.38-4.41) for class I (P = 0.67) and OR of 2.80 (95% CI 0.62-12.62) for the combined classes II and III (P = 0.18)].

CONCLUSION: Maternal BMI was not associated with fetal acidosis in term twin pregnancies. Further research is required to corroborate study findings due to small sample size.