Pregnancy following bariatric surgery: maternal considerations
Creators: name: Kanu, Chidimma
Publisher: name: Imperial College London
Year: 2021

description: Background The mechanism behind the perinatal complications associated with obesity in pregnancy is not fully understood. There is convincing evidence that pregnancies following bariatric surgery have a lower incidence of gestational diabetes (GDM), pre-eclampsia (PE), large for gestational age (LGA) neonates, higher incidence of small for gestational age (SGA) neonates and moderately preterm birth. The mechanism for this is also unknown, however, could be related to changes in maternal insulin resistance and other metabolic pathways involved in glucose and fat metabolism. Aims 1. To investigate the effects of bariatric surgery on maternal insulin resistance, waist to hip ratio (WHR), blood pressure and components of fat and glucose metabolism such as adipokines, pro-inflammatory hormones, incretins and metabolites. 2. To compare the lipoprotein profile of obese women and women with a normal BMI in the third trimester, without previous bariatric surgery. Method We conducted a prospective, longitudinal study comparing pregnant women with previous bariatric surgery to those without surgery. The following were assessed: 1. Insulin, glucose, glycosylated haemoglobin (HbA1c), Homeostasis Model Assessment of insulin resistance (HOMA-IR) and the Matsuda Index were measured using fasting blood samples collected at 28 weeks gestation. 2. Maternal weight, height, waist to hip ratio (WHR) and blood pressure were measured at all antenatal visits. 3. Fasting blood samples at 28+0-30+0 weeks’ gestation were used to measure peptide hormones, adipokines, pro-inflammatory hormones and incretins. 4. Untargeted metabolomics with proton Nuclear Magnetic Resonance (H1 NMR) was performed on samples obtained at six time points: 11+0-14+0 (T1), 20+0-24+0 (T2), 28+0-30+0 (T3), 30+0-33+0 (T4) and 35+0-37+6 (T5) weeks’ gestation, and within 72 hours of delivery (T6). H1 NMR lipoprotein profiling was performed for pregnant women recruited without previous bariatric surgery at 28+0-30+0 weeks’ gestation. Results were compared between women with normal BMI and women who were obese (BMI ≥ 30kg/m2). Results The no surgery group had higher median insulin resistance (IR), [2.20 (IQR 1.53-3.38)] compared to the post bariatric surgery group [1.15 (IQR 1.04 -2.07); p &lt;0.05] and post malabsorptive bariatric surgery group, [1.08 (0.99 – 1.23; p &lt;0.05]. Pregnant women with previous bariatric surgery had significantly lower leptin levels at 28-30 weeks [13.3ng/ml (IQR 9.71-15.36)] compared to women with no surgery [20.84ng/ml (IQR 18.12-24.1); p&lt;0.05]. Maternal adiponectin levels at 28-30 weeks of gestation were higher in the post bariatric women [4.9µg/ml (IQR 2.9-6.7)] compared to no surgery women [2.43 µg/ml (IQR 1.8-3.2); p &lt;0.05]. Pregnant women with previous malabsorptive bariatric surgery had an altered serum metabolome by T4 (30-33 weeks) and T5 (35-37 weeks) compared to those without bariatric surgery (p=0.027 and p=0.006, respectively). There is a lower serum level of unsaturated lipids, isobutyrate, leucine, isoleucine and N-acetyl glycoprotein and higher level of glutamine and D-ß-hydroxybutyrate. The lipoprotein profile of women at 28 weeks gestation without surgery showed that, compared to women with normal BMI, obese women have higher levels of HDL4 Triglyceride (p=0.02) VLDL1 Phospholipid (p=0.023) and VLDL1 Cholesterol (p=0.02) and lower levels of HDL, HDL1 cholesterol (p=0.02, 0.02), LDL2, LDL3 cholesterol (p=0.03, 0.02) and HDL1 phospholipid (p=0.03). Conclusion The study has demonstrated that women with previous bariatric surgery have a reduction in insulin resistance, especially post malabsorptive surgery. In the third trimester, they have a lower leptin and higher adiponectin level. These findings may explain the reduced incidence of GDM and LGA babies seen in this group.