Nutritional concerns during post-op pregnancy;Women who become pregnant after bariatric surgery are at high risk for low micro-nutrient levels, especially for vitamins A and B-1 and albumin, according to research published online at PlusOne.
The researchers from the University Hospitals Leuven, Leuven, Belgium, prospectively evaluated micronutrient levels during pregnancy and the effect of a standardised supplementation strategy in pregnant women who have undergone bariatric surgery.
The multi-centre prospective cohort study was conducted from April 2009 until January 2011 at the antenatal clinics of Obstetrics and Gynecology departments in five hospitals in Belgium. Fifty four patients were recruited into the study of which 20 (37%) underwent a restrictive procedure and 34 (63%) a malabsorptive or mixed procedure. One subject suffered a miscarriage and as a result the final analysis was performed on data from 49 women (91% of the originally recruited population).
All subjects were of West-European origin older than 18 years with a medical history of bariatric surgery presenting at the antenatal clinic before 15 weeks amenorrhea were eligible for recruitment.
During the first antenatal visit, all patients were recommended to use a standard prenatal multivitamin supplement. In case of observed micronutrient deficiencies during the first or second trimester and at delivery, the obstetrician provided a prescription for the required supplementation.
Both groups were comparable for age at inclusion, height, mean preoperative weight and the time interval between the surgery and conception. 39% of the women were nullipara and 25% smoked at inclusion. The postoperative weight loss was significantly different between both groups, with the highest weight loss in the malabsorptive group. This resulted in a significantly lower pre-pregnancy weight and body mass index of the malabsorptive group compared to the restrictive group.
The researchers found that during pregnancy there was a decline in mean vitamin A concentration was observed (p=0.037) and was comparable in both groups, but the concentration in the restrictive group was consistently lower than in the malabsorptive group (p = 0.034).
Another blood marker that declined significantly during pregnancy was vitamin B-1 (p=0.018), without a difference between groups. A significant time by group interaction (p=0.004) was noted for vitamin B-12: in the restrictive group the mean concentration decreased, whereas the mean concentration in the malabsorptive group increased.
Ferritin and hemoglobin levels declined significantly during pregnancy (p=0.001 and p=0.002 respectively). A last blood marker that declined during pregnancy was albumin (p = 0.001). The mean concentration of albumin also differed between groups with the lowest mean concentration in the restrictive group (p=0.004). No significant changes during pregnancy, group difference or time by group interactions were observed for folic acid, alanine aminotransferase levels and for vitamin D and vitamin E levels.
Table 1 summarizes the association between supplement intake and micronutrient deficiency across the different pregnancy trimesters. The majority of women who had a micronutrient deficiency in the first pregnancy trimester reported to already take a supplement at that time (n=37/40, 92.5%, p=0.380).
Of the 45 women with a micronutrient deficiency in the second pregnancy trimester, and with corresponding data on self-reported supplement intake in the first trimester, 41 women (n=41/45, 91.1%) was taken a supplement in trimester one of pregnancy (p=0.273). No association was found between micronutrient deficiency in trimester two and supplement intake in that same period (p=0.377).
Also no associations were seen between micronutrient deficiencies at birth and self-reported supplement intake during trimester one and two of pregnancy (p=0.668 and p=0.839) and at birth (p=0.545). Again, the majority of women with a micronutrient deficiency at birth reported to take a supplement during trimester one (n=38/43, 88.4%), trimester two (n=38/41, 92.6%) and around the moment of birth itself (n=33/41, 80.5%).
During the first trimester, almost 90% of the pregnant women reported to take a supplement (n=44). A multivitamin was taken by 28 (57.1%) women and an iron supplement by 10 women (20.4%). During the second trimester, multivitamins were taken by 10 (20.4%) women. Fourteen women (29.1%) took a vitamin B-12 supplement and 6 (12.5%) women an iron supplement. At delivery, a multivitamin, an iron supplement and a vitamin B-12 supplement were taken by respectively 4 (8.2%), 24 (50.0%) and 11 (22.9) women.
There was one case of pre-eclampsia and one of woman was diagnosed with gestational diabetes in the malabsorptive group. Two patients were diagnosed with PIH in the restrictive group and three in the malabsorptive group. Mean birth weight was significantly lower in the malabsorptive group (3.06±0.56) compared to the restrictive group (3.43±0.47) (p=0.024). There was one preterm birth (<37 weeks of gestation) in the restrictive group and four in the malabsorptive group (p=0.639). No low birth weight was detected in the restrictive and two in the malabsorptive group (p=0.526). Besides the miscarriage and the termination of pregnancy due to the diagnosis of neural tube defect mentioned earlier, two more relevant adverse events occurred. Two patients of the malabsorptive group were diagnosed with a small bowel obstruction (Table 2).
Table 2: Maternal and neonatal outcomes.
Most micronutrients were depleted and declined significantly during pregnancy.
The proportion of women with low vitamin A and B-1 levels increased to respectively 58 and 17% at delivery (p=0.005 and 0.002). The proportion of women with vitamin D deficiency decreased from 14% at trimester 1 to 6% at delivery (p=0.030).
Mild anaemia was found in respectively 22 and 40% of the women at trimester one and delivery. In the first trimester, most women took a multivitamin (57.1%). In the second and third trimester, the majority took additional supplements (69.4 and 73.5%). No associations were found between supplement intake and micronutrient deficiencies.
“We show that women undertaking pregnancy after bariatric surgery are at high risk for low micronutrient levels, especially for vitamins A and B-1 and albumin,” the authors note. “Our results need to be carefully interpreted in the light of both the physiological pregnancy changes in absorption and metabolism, as well as the specific alternations due to obesity surgery.”