Guest Post: Everything You Must Know About Pregnancy and Weight Gain
Today’s post is from Zach Ferraro, PhD, a former CON-SNP National Executive member (2008-12), CON Boot Camper (2008) and Inaugural recipient of CON Rising Star Award (2012). Currently, Zach is a clinical research associate in the Division of Maternal-Fetal Medicine at the Ottawa General Hospital and PT Professor in Human Kinetics at the University of Ottawa. He is also a member of the CON 5 As for pregnancy working group. Regular readers of these pages will recall that the intrauterine environment plays a vital role in healthy neonatal development and is directly influenced by maternal nutrition, physical activity, xenobiotics and pregnancy weight gain. This interaction is commonly referred to as ‘fetal programming’ or more appropriately termed fetal plasticity. That is, the ability of the developing fetus to grow and respond to external stimuli whether intrauterine or environmental. Thus, all prenatal exposures, positive and negative, have the potential to affect the short- and long-term health of the child. It is now well-established that excess gestational weight gain (GWG) is an independent predictor of large for gestational age (LGA) neonates and postpartum weight retention (PPWR) in the mother. Simply, moms who gain greater than the recommended amount of weight, according to their pre-pregnancy BMI, subsequently carry this excess weight forward into the next pregnancy causing a rightward shift in their BMI after delivery. In addition, babies born large (LGA) tend to track their excess weight throughout life and are at greater risk of becoming obese as adults. Although the mechanisms explaining these associations are far from unraveled, both LGA and PPWR exacerbate what is referred to as the intergenerational cycle of obesity. So what can care providers do to help minimize the ill-effects of excessive GWG? Several lifestyle interventions during pregnancy are reported in the literature and have yielded mixed results. This is largely due to heterogeneity in intervention type (diet or physical activity or psychological support or all the above) and intensity (intensive clinical intervention vs. hands off approach). We, in addition to others, have also reported that knowledge transfer between patients and providers may be partially responsible for the limited treatment effects seen in some interventions. Nonetheless, in the absence of any between group differences in GWG guideline adherence and maternal-fetal outcomes between lifestyle intervention and standard care, it is important to remember that healthy living behaviours were not harmful and may have resulted in increased fitness and/or alterations in… Read More »
No Easy Path To Dropping Pounds After Pregnancy
Gaining excessive weight during pregnancy and retaining much of it after delivery is ones of the most common drivers of adult obesity in women. Emerging evidence supports the notion that both may well be detrimental to the health of mothers (and their kids). Unfortunately, it appears that behavioural intervention during pregnancy to reduce long-term weight retention is a lot more challenging that one may expect. This is the rather disappointing outcome of a randomised controlled trial by Suzanne Phelan and colleagues, published in the American Journal of Clinical Nutrition. The trial included 400 US Women, half of who were overweight or obese, randomly assigned to a behavioural intervention or control group beginning around the 13th week into their pregnancy. The intervention (Fit for Delivery) consisted of one face-to-face visit with an interventionist at the onset of treatment, the provision of body-weight scales, food records, and pedometers to promote adherence to daily self-monitoring, weekly postcards prompting healthy eating and exercise habits, personalized graphs of their weight gain with feedback, and supportive phone calls from the dietitian during the intervention. This intervention continued till delivery. Four out of five of the participants completed the 12-mo assessment. Overall the intervention did not increase the participants’ chances of achieving their prepregnancy weights. Even the completer analysis showed non-significant trends at best – this despite women in the intervention group reporting higher levels of dietary restraint and more frequent self-monitoring of body weight. Thus, this level if intervention, which far exceeds usual care during pregnancy for most women, does not appear to effectively reduce post-pregnancy weight retention. Incidentally, the only predictors of excessive weight retention were pre-pregnancy BMI and excessive gestational weight gain. Breastfeeding, age, parity, and delivery weeks were not. Thus, although excessive pregnancy weight gain and post-pregnancy weight retention are common problems with significant negative health impacts on both mother and child, it will apparently take far more than an additional visit with a dietitian and exercise counsellor or postcards and telephone reminders to impact body weight. I wonder if anyone else is not all too surprised by these findings? @DrSharma Edmonton, AB Phelan S, Phipps MG, Abrams B, Darroch F, Grantham K, Schaffner A, & Wing RR (2014). Does behavioral intervention in pregnancy reduce postpartum weight retention? Twelve-month outcomes of the Fit for Delivery randomized trial. The American journal of clinical nutrition, 99 (2), 302-11 PMID: 24284438 .
Newborns of obese parents have altered DNA methylation patterns at imprinted genes
Regular readers will be well aware of the accumulating data on the role of maternal (and perhaps paternal) obesity on the developing fetus that can result in a lifelong predisposition for obesity in the offspring. Now a study by Soubry and colleagues form the University of Leuven, Belgium, published in the International Journal of Obesity, provides evidence of epigenetic modification on key genes involved in human development in the offspring of obese parents. The study examined parental preconceptional obesity in relation to DNA methylation profiles in newborns at multiple human imprinted genes important in normal growth and development (MEG3, MEST, PEG3, PLAGL1, SGCE/PEG10, and NNAT). After adjusting for potential confounders and cluster effects, paternal obesity was significantly associated with lower methylation levels at the MEST, PEG3, and NNAT genes. From these studies, the authors conclude that, altered methylation may occur at multiple imprint regulatory regions in children born to obese parents, compared to children born to non-obese parents. Thus, their data suggests a preconceptional influence of parental life-style or overnutrition on the reprogramming of imprint marks during gametogenesis. Interestingly enough, their data also suggests that developing sperm may well be susceptible to environmental insults (in this case weight gain). These findings are of considerable importance as other evidence suggests that the acquired imprint instability may be carried on to the next generation and increase the risk for chronic diseases such as obesity in adulthood. @DrSharma Montreal, QC Soubry A, Murphy SK, Wang F, Huang Z, Vidal AC, Fuemmeler BF, Kurtzberg J, Murtha A, Jirtle RL, Schildkraut JM, & Hoyo C (2013). Newborns of obese parents have altered DNA methylation patterns at imprinted genes. International journal of obesity (2005) PMID: 24158121 .
Transgenerational Metabolic Effects of Maternal Food Intake in Fruit Flies
Regular readers will be well aware of the accumulating epidemiological, clinical and experimental data showing that maternal dietary habits before and during pregnancy can “permanently” modify their offspring’s metabolism and risk for condition like obesity through epigenetic “reprogramming”. The major implication of these findings are that much of the childhood obesity epidemic can perhaps be explained by the increasing adiposity and older age of present day mothers – a trend that has been well underway for decades. This ability to genetically reprogram metabolism within the space of a single generation appears to be firmly engrained in our biology and dates back to the earliest developmental characteristics of even the most genetically distant species. Thus, a paper by Luciano Matzkin and colleagues, published in PLOS One, shows that peradult parental diet can affect offspring development and metabolism even in the fruit fly (drosophila melanogaster). In their study, the researchers not only found that adult fruit flies emerging from larvae reared on isocaloric diets differing in their amounts of protein relative to sugar show differences in development times and metabolism, but that these alterations are passed on to their offspring, even when these are eating a normal diet. Interestingly, there appeared to be additional genetic effects on how much of these epigenetic changes were transferred to the offspring, suggesting another level of complexity in this relationship. Be that as it may, the evidence is clear that trans-generational metabolic reprogramming can occur within a single generation thus challenging the common view that genes cannot possibly play a role in the current obesity epidemic. Anyone arguing that it would take 100s or 1000s of years for our genes to have changed enough to explain the onset of the obesity epidemic over the past few decades, is simply underestimating both the speed and impact of genetic changes that can occur within a single generation. On a positive side, there is now at least some data suggesting that such changes may be avoided through interventions that promote healthier diets, exercise and limit excess weight gain during pregnancy. This may yet be our best bet in reducing the incidence of childhood obesity. @DrSharma Edmonton, AB Matzkin LM, Johnson S, Paight C, & Markow TA (2013). Preadult parental diet affects offspring development and metabolism in Drosophila melanogaster. PloS one, 8 (3) PMID: 23555695 .
Is Childhood Obesity Largely Driven by Maternal BMI and Smoking Behaviour?
Countless factors have been implicated in the increase in childhood obesity that has occurred in the past decades. These include increasing sedentariness and overconsumption of calories. However, data on this is far less consistent or convincing that one would assume. Lately, considerable interest has focussed on biological factors directly related to fetal and early prenatal development that may set the stage for subsequent weight due to “metabolic programming”. This notion finds further support in a study by Sheila Williams and colleagues from the University of Otago, Dunedin, New Zealand, published in Pediatric Obesity. The researchers analysed data from two cohort studies: the Dunedin Multidisciplinary Health and Development Study (DMHDS), that included 974 kids born in 1972–1973 and the Family Lifestyle, Activity, Movement and Eating Study (FLAME), that included 241 kids born in 2001–2002. Over the 29 years that lie betweeen the two cohorts, kids became significantly heavier as did their moms, whereby the increased BMI of the mothers “accounted” for a substantial proportion of the increase in kids’ weights. Similarly, although overall rates of maternal smoking reduced by about 15%, kids of mothers who smoked during pregnancy were heavier by age 7 than the kids of moms who didn’t. Thus, maternal BMI and smoking behaviours turned out to be the most significant predictors of childhood weight gain (while changes in behavioural factors, including sleep and television viewing, appeared to have little effect). But, as the authors hasten to point out, such studies cannot prove or disprove causal relationships. Nevertheless, these findings are certainly consistent with the notion that maternal influences during fetal development or in early childhood may well predispose offspring to greater weight gain, thereby accounting for a substantial proportion of the childhood obesity epidemic. @DrSharma Edmonton, AB Williams SM, Taylor RW, & Taylor BJ (2013). Secular changes in BMI and the associations between risk factors and BMI in children born 29 years apart. Pediatric obesity, 8 (1), 21-30 PMID: 23001951 .
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