WLS and Pregnancy: A Trade-Off of Risks

One of the ways that Weight Loss Surgery (WLS) is marketed to "obese" women of childbearing age is by preying on their desire to have children and their fears of complications.  WLS is marketed as a sure way to decrease the risks around pregnancy and obesity and to increase the chances for a healthy baby.

And to be fair, research does seem to show that WLS decreases the rate of some complications like gestational diabetes. However, does this come at a price?

One risk that tends to be vastly underemphasized in the WLS research literature is the risk for fetal undergrowth, that is, undersized babies (usually called "Small-for-Gestational-Age" or SGA babies).

Although WLS doctors tend to shrug off this risk, research shows that SGA babies tend to be more at risk for later health problems and do more poorly at birth.

Are doctors trading off one risk for another, more lifelong risk instead?



References

Obstet Gynecol. 2012 Mar;119(3):547-54. Pregnancy outcomes in women after bariatric surgery compared with obese and morbidly obese controls. Lesko J, Peaceman A.   PMID: 22353952

OBJECTIVE: To estimate the rates of pregnancy outcomes of women after bariatric surgery relative to women in a control groups. METHODS: The study was a chart review. Presurgery and prepregnancy body mass index (BMI) were calculated for 70 patients who had undergone bariatric surgery and who had a subsequent singleton pregnancy. Four control patients were then randomly selected for each case patient: two with a BMI within 6 points of the average presurgery BMI and two with a BMI within 6 points of the average prepregnancy BMI. The primary outcomes were the rates of gestational diabetes or hypertensive disorders of pregnancy. RESULTS: There was a significant decrease in rate of gestational diabetes in bariatric surgery patients (0.0%) as compared with both control groups (morbidly obese 16.4%, obese 9.3%; corrected odds ratio (OR) morbidly obese 0.04, with a 95% confidence interval [CI] 0.00-0.62, P<.01; corrected OR obese 0.07, CI 0.00-1.20, P=.01). There was no significant difference in the rate of hypertensive disorders of pregnancy with bariatric surgery. Additionally, neonates were significantly more likely to be small for gestational age (SGA) in the bariatric surgery group (17.4%) than the morbidly obese group (5.0%) (OR 3.94, CI 1.47-10.53, P<.01). CONCLUSION: Bariatric surgery is associated with reduction in gestational diabetes in a subsequent pregnancy, but possibly at the expense of an increase in SGA neonates.

Diabet Med. 2003 May;20(5):339-48. Is birth weight related to later glucose and insulin metabolism?--A systematic review. Newsome CA, et al.  PMID: 12752481

AIM: To determine the relationship of birth weight to later glucose and insulin metabolism. METHODS: Systematic review of the published literature. Data sources were Medline and Embase. Included studies were papers reporting the relationship of birth weight with a measure of glucose or insulin metabolism after 1 year of age, including the prevalence of Type 2 diabetes mellitus(DM). Three reviewers abstracted information from each paper according to specified criteria. RESULTS: Forty-eight papers fulfilled the criteria for inclusion, mostly of adults in developed countries. Most studies reported an inverse relationship between birth weight and fasting plasma glucose concentrations (15 of 25 papers), fasting plasma insulin concentrations (20 of 26), plasma glucose concentrations 2 h after a glucose load (20 of 25), the prevalence of Type 2 DM (13 of 16), measures of insulin resistance (17 of 22), and measures of insulin secretion (16 of 24). The predominance of these inverse relationships and the demonstration in a minority of studies of other directions of the relationships could not generally be explained by differences between studies in the sex, age, or current size of the subjects. However, the relationship of birth weight with insulin secretion was inconsistent in studies of adults. CONCLUSIONS: The published literature shows that, generally, people who were light at birth have an adverse profile of later glucose and insulin metabolism. This is related to higher insulin resistance, but the relationship to insulin secretion in adults is less clear.

Diabetes Care. 1999 Jun;22(6):944-50. Birth weight, type 2 diabetes, and insulin resistance in Pima Indian children and young adults. Dabelea D, et al.   PMID: 10372247

OBJECTIVE: To investigate the mechanisms underlying the association between birth weight and type 2 diabetes in a population-based study of 3,061 Pima Indians aged 5-29 years. RESEARCH DESIGN AND METHODS: Glucose and insulin concentrations were measured during a 75-g oral glucose tolerance test, and insulin resistance was estimated according to the homeostatic model (homeostasis model assessment-insulin resistance [HOMA-IR]). Relationships between birth weight, height, weight, fasting and postload concentrations of glucose and insulin, and HOMA-IR were examined with multiple regression analyses. RESULTS: Birth weight was positively related to current weight and height (P < 0.0001, controlled for age and sex, in each age-group). The 2-h glucose concentrations showed a U-shaped relationship with birth weight in subjects > 10 years of age, and this relation was independent of current body size. In 2,272 nondiabetic subjects, after adjustment for weight and height, fasting and 2-h insulin concentrations and HOMA-IR were negatively correlated with birth weight. CONCLUSIONS: Low-birth-weight Pimas are thinner at ages 5-29 years, yet they are more insulin resistant relative to their body size than those of normal birth weight. By contrast, those with high birth weight are more obese but less insulin resistant relative to their body size. The insulin resistance of low-birth-weight Pima Indians may explain their increased risk for type 2 diabetes.