Whilst bariatric and metabolic surgery (BMS) can reduce obesity-related pregnancy complications, it can inadvertently result in an increase in potential risks that may result in adverse outcomes for both mothers and babies, according to a study led by researchers from Hamad Medical Corporation, Doha, Qatar. These risks include nutritional deficiencies, anaemia, changes in maternal glucose metabolism, and the possibility of having children who are small for gestational age. The findings were reported in the paper, ‘Maternal and neonatal risks and outcomes after bariatric surgery: a comparative population based study across BMI categories in Qatar’, published in Scientific Reports.
The study authors noted that there are limited studies on perinatal outcomes other than the size for gestational age and preterm birth. Therefore, they designed a study to to assess the medical risk factors, and pregnancy and neonatal outcomes of pregnant women who have undergone BMS in comparison to pregnant women without a history of BMS in Qatar.
The study used electronic medical record registry data from the PEARL-Peristat Study at HMC and included 6,212 singleton births with available data on post-BMS and BMI. Among these, 315 (5.07%) women had undergone BMS. To form a comparison group, they included pregnancies in women without a history of BMS, categorised as women living with obesity (n=1,918; 30.87%), overweight (n=1,953; 31.44%) and normal weight controls (n=2,026; 32.61%).
Outcomes
The researchers found significant differences were observed between these two groups - data availability was higher among older mothers (≥ 35 years) vs. younger mothers (22.5% vs. 18.1%; p<0.001) and hypertension was more prevalent amongst women who were included in the study (1.8% vs. 0.9%; p<0.001).
The mode of delivery also differed significantly, with caesarean delivery being more common among those with available data (32.5% vs. 28.4%; p<0.001). Induced labour was more frequently reported in the data-available group (17.8% vs. 14.3%; p<0.001), as was gestational diabetes mellitus (30.6% vs. 22.9%; p<0.001). Elective Caesarean Section (CS) rates were higher among those with available data (52.5% vs. 48.3%; p<0.01). In addition, the prevalence of Diabetes Mellitus (DM) was significantly greater in the data-available group (5.5% vs. 1.8%; p<0.001). There were no significant differences in relation to the rest of the demographic and clinical factors.
Pregnant women aged ≥ 35 years were more likely to give birth to babies with low birth weight (< 2,500g) and have low Apgar score at 5min. Women with obesity had a higher prevalence of gestational diabetes mellitus (GDM), chronic/essential hypertension, induction of labour, NICU admission and caesarean delivery vs. other groups. Pregnant women with obesity are also more likely to be aged ≥ 35 years compared to the non-surgery BMI groups. Preterm birth was found to be more likely amongst women with obesity, overweight and post-BMS groups compared to normal.
Qatari women, aged 35 years and above, DM, parity (higher than 1) and Essential Hypertension (EHTN) were significantly more likely to be from the obesity group vs. the normal weight group even after adjustment for other significant factors from the univariate analysis. The same results were found for the overweight pregnant women (except for EHTN) and post-BS (except for DM).
Post-BMS were significantly more likely to be Qataris and to have EHTN before and after adjustment. On the other hand, pregnant women with obesity in comparison to overweight were more likely to have multiple births (1–4 and > 5), DM and EHTN even after adjustment for other significant factors from the univariate analysis. Post-BMS pregnant women were significantly more likely to be Qataris and less likely to be DM vs. pregnant women with obesity even after adjustment for other significant factors from the univariate analysis.
Univariate and multivariate regression analyses indicated that all groups, including post-BS, patients living with obesity and overweight women, had significantly higher likelihoods of caesarean delivery vs. women with normal weight, even after adjusting for the significant risk factors from the univariate analysis at stage one.
Post-BMS women were significantly more likely to have preterm, low birthweight (< 2,500g) or stillbirth babies vs. normal weight women, and were more likely to have low birthweight babies (including term low birth weight) vs. overweight and women with obesity, even after adjusting for the significant risk factors from the univariate analysis at stage one.
Pregnant women with obesity were also more likely to have preeclampsia and induced labour vs. women with normal weigh, and induced labour was a significant outcome for obesity versus overweight women as well even after adjusting for the significant risk factors from the univariate analysis at stage one.
Overweight women were more likely to have assisted births and extremely premature babies vs. women with obesity, even after adjusting for the significant risk factors from the univariate analysis at stage one. Both women with obesity and overweight had significantly higher odds of GDM vs. normal weight and post-BS women, with women with obesity being more likely to have GDM than overweight women even after adjusting for the significant risk factors from the univariate analysis at stage one.
The researchers stated that these findings contribute not only to the Qatari context but also provide a valuable benchmark for global discussions on the impact of obesity on pregnancy outcomes
“As obesity rates surge, our study highlights the inextricable link between obesity in women of childbearing age and adverse health conditions, particularly during pregnancy...” the authors concluded. “These must be addressed proactively, ideally during preconception counselling. The identified gaps in literature call for further research to elucidate the correlation between nutritional deficits and newborn weight, thereby enhancing the holistic understanding of pregnancy outcomes in this unique demographic. Future studies should consider the interaction of genetic and environmental factors, utilising a precision medicine approach along with population health analyses.”
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