After bariatric surgery, the intake and absorption of micronutrients is decreased. During pregnancy following bariatric surgery, the increased demand for micronutrients may lead to more pronounced nutrient deficiencies. Overall, low maternal concentrations of vitamins A, B12 and D, folic acid, iron, and zinc are frequently reported during pregnancy after surgery. Potential neonatal adverse effects that are associated with maternal deficiencies in pregnancy include preterm birth, foetal growth restriction, congenital malformations, and neurological and developmental impairment.

NEWBIE Study

The NEWBIE study (Nutritional status of prEgnant Women following BariatrIc surgEry) is a multicenter observational cohort study that was conducted from November 2018 until October 2022 at 3 general hospitals in the Netherlands (Rijnstate hospital, Arnhem; Máxima Medical Center, Veldhoven; Hospital Gelderse Vallei, Ede).

• All pregnant women older than 18 years with a medical history of bariatric surgery presenting at the bariatric or antenatal clinic were eligible for recruitment.
• The final population for data analysis consisted of 119 participants of which 80 had undergone Gastric Bypass (RYGB, 67%) and 39 Gastric Sleeve (SG, 33%).
• Data on supplement use and routine blood samples including haemoglobin, ferritin, folic acid, vitamins A, B1, B6, B12 and D, and calcium were analysed every trimester (T1;T2;T3).
• Participants were categorized as either users of WLS-multivitamins or users of sMVS. sMVS were defined as regular over-the-counter MVS or prenatal supplements.

Gastric Bypass Patients

During pregnancy following RYGB, more participants used WLS-multivitamins compared to sMVS (T1: 70% vs 30%; T2+T3: 75% vs 25%).

Users of WLS-multivitamins had higher levels of hemoglobin, ferritin and folic acid and lower serum levels of vitamin B6 during pregnancy compared to sMVS users.

With respect to folic acid, serum concentrations significantly decreased during pregnancy, but remained far above the lower reference limit in both MVS groups. Furthermore, the prevalence of folic acid deficiencies was low (± 6%) and did not differ between the groups.

In contrast, levels of hemoglobin and ferritin decreased within the lower range.

 

Iron

Iron is mainly crucial for red blood cell production and low iron status has been associated with maternal anemia, preterm delivery, and low neonatal birth weight. Overall, the prevalence of iron deficiency was lower in the WLS-MVS group compared to the sMVS group (29% vs 51%) during pregnancy following RYGB.

 

Vitamin B6 & Vitamin A

For vitamin B6, serum vitamin B6 concentrations were near the upper reference limit in both MVS groups. Although exposure to extremely high doses of vitamin B6 (>50 mg/day) did not appear to be associated with an increased risk for major malformations during pregnancy in previous research, attention on elevated levels is needed as they may cause maternal peripheral neuropathy. In the present study, elevated vitamin B6 levels were less prevalent in the WLS-MVS group compared to the sMVS group (19% vs 44%).

We also observed a trend towards higher serum vitamin A concentrations and less vitamin A deficiencies (17% vs 39%) in WLS-MVS users compared to sMVS users. Overall, only one participant in the WLS-MVS group presented with an elevated serum vitamin A level during pregnancy (T2: 3.71 µmol/L).

 

Beta-carotene

Although supplementation with beta-carotene is preferred over the use of retinol during regular pregnancy due to the well-documented risk of teratogenic malformations, most WLS-MVS contain about 600-800 µg retinol, which is far below the safe upper level of 3000 µg as indicated by the European Food Safety Authority. Besides, serum vitamin A concentrations significantly decreased within the lower range over the course of pregnancy and vitamin A deficiencies were prevalent during pregnancy after RYGB. Therefore, continuing the use of WLS-MVS during pregnancy after BS is considered safe and may even be preferred over the use of supplements containing beta-carotene because of its low conversion efficiency.

 

We did not find any differences in vitamin B12, vitamin B1, vitamin D and calcium status between the two MVS groups during pregnancy following RYGB.

Sleeve Gastrectomy Patients

During pregnancy following Sleeve Gastrectomy, the percentage of participants using WLS-MVS was comparable to those using sMVS (T1: 52% vs 48%, T2: 46% vs 54%, T3: 50% vs 50%).

• WLS-MVS users had higher serum levels of vitamin D, but lower serum levels of vitamin B1 than sMVS users.
• The lower vitamin B1 levels observed in the WLS-MVS group may be explained by the prevalence of hyperemesis gravidarum, which occurred in 3 women who all underwent SG and used WLS-MVS. Persistent vomiting is a risk factor for thiamine deficiency, which can ultimately result in Wernicke’s encephalopathy. Nevertheless, serum vitamin B1 concentrations were far above the lower reference limit in both groups and deficiencies during pregnancy were rare.

We did not find any differences in haemoglobin, ferritin, folic acid, vitamin B12, vitamin A, vitamin B6 andcalcium status between the two MVS groups. There were no participants with an elevated serum vitamin A level during pregnancy after Sleeve Gastrectomy.

Conclusion

Based on the findings of this study, we conclude that using specialized supplementation during pregnancy after bariatric surgery is preferred over using standard supplementation. Future research is needed to further optimize and individualize supplementation for this high-risk population, particularly after SG.

Click here to download Table1: General characteristics of the study population according to type of BS and Table2: Prevalence of serum levels below the lower reference limit during each trimester of pregnancy (T1, T2, T3) for WLS-MVS users versus sMVS users, stratified by type of BS.

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Source: Heusschen, L., Berendsen, A. A., van Bon, A. C., van Laar, J. O., Krabbendam, I., & Hazebroek, E. J. (2024). Nutrient status and supplement use during pregnancy following metabolic bariatric surgery: a multicenter observational cohort study. Obesity Surgery, 1-11.