Endocrine Abstracts

Introduction

Vitamin B12 (vB12) deficiency has been associated with a plethora of hematologic, neurologic and metabolic abnormalities. In pregnant women, several studies have demonstrated an association with a greater maternal body mass index (BMI), maternal and offspring insulin resistance, gestational diabetes mellitus (GDM) and even later type 2 diabetes.

Aim of the study

Evaluation of maternal and fetal outcomes of pregnant women with GDM with and without vB12 deficiency.

Material and methods

Retrospective study based on data from 200 pregnant women with GDM evaluated between 2018 and 2019 that had B12 levels measured at the initial observation. It was considered vB12 deficiency if levels < 188 pg/ml.

Results

We considered two groups: Group 1 (n = 132) with vB12 within normal range; Group 2 (n = 68) with vB12 deficiency. Serum samples were collected at 27.6 ± 8 weeks of pregnancy. Mean vB12 level in Group 2 was 134 ± 106.2 pg/ml. GDM was diagnosticated in 46% vs 36.5% during the first trimester and in 54% vs 63.5% during the 2nd trimester. There was no statistical difference between groups in terms of age (33.3 ± 5.4 vs 33.5 ± 4.7years), initial HbA1c (5.4 ± 0.8% vs 5.3 ± 0.6%), HOMA-IR (3.1 vs 3.3), hemoglobin level (11.6 ± 1.6 vs 11.5 ± 2.1 g/l), percentile of fetal abdominal circumference in 3rd trimester (58 ± 19.5 vs 55 ± 22), gestational hypertension (3.7% vs 4.4%), pre-eclampsia (2.2% vs 1.4%), hydramnios (8.3% vs 8.8%) and pre-term delivery (4.5% vs 5.8%). All patients were already medicated with iron plus folic acid whereby deficiencies were not detected. The mean gestational age of delivery was 38 weeks without differences between groups. Group 2 had higher pregestational BMI (28.1 ± 7 vs 30.8 ± 5 kg/m²; P = 0.03), 3^rd trimester BMI (32.1 ± 3 vs 34 ± 6 kg/m²; P = 0.04), higher rate of infectious complications in the postpartum period (0.7% vs 6.3%; P = 0.04) and tendency for macrosomia (4.3% vs 7.3%; P = 0.06). Although the rate of cesarean section was similar between groups (40% vs 36.7%, P = ns) the need to perform emergent cesarean section was higher in Group 2 (13.6% vs 60%; P = 0.01). Regarding the neonatal morbidity, the incidence of phototherapy due to hyperbilirubinemia was similar. Concerning postpartum reclassification, no statistical significance was observed between groups (diabetes mellitus in 6% for Group 1 and 9.7% for Group 2).

Conclusions

Pregnant women with GDM and vB12 deficiency had higher prevalence of obesity, emergent cesarean section and maternal complications in the postpartum period. More studies with a larger number of participants are needed to validate these results and, eventually, to find new associations with vB12 deficiency.