Objectives: To systematically review the evidence from prospective and retrospective cohort studies on the association between gestational weight gain (GWG) and offspring’s body weight.
Methods: Electronic databases PubMed, Web of Science, CINAHL, and Academic Search Premiere were searched from inception through March 18, 2013. Included studies (n=23) were English articles that examined the independent associations of GWG with body mass index (BMI) and/or overweight status in the offspring aged 2 to 18.9 years. Two authors independently extracted the data and assessed methodological quality of the included studies.
Results: Evidence from cohort studies supports that total GWG and exceeding the Institute of Medicine maternal weight gain recommendation were associated with higher BMI z-score and elevated risk of overweight or obesity in offspring. The evidence of high rate of GWG during early- and mid-pregnancy is suggestive. Additionally, the evidence on inadequate GWG and net GWG in relation to body weight outcomes in offspring is insufficient to draw conclusions.
Conclusions: These findings suggest that GWG is a potential risk factor for childhood obesity. However, findings should be interpreted with caution due to measurement issues of GWG and potential confounding effects of shared familial characteristics (i.e., genetics and maternal and child’s lifestyle factors).
Alex’s Notes: Maternal gestational weight gain (GWG) is the amount of weight that a woman gains during her pregnancy. The seemingly inevitable food cravings and fat gain during pregnancy are necessary to ensure adequate nutrition for the developing offspring, but like all things in America, if some is good more must be better. I mean, about 46% of the pregnant women in the U.S. between 1997 and 2007 gained more weight than the Institute of Medicine (IOM) recommends (about 15 lbs). I personally know people who think that getting fat during pregnancy is normal, and honestly I think they simply use the pregnancy as an excuse to do nothing and stuff their face. From an evolutionary perspective, clearly that makes sense (note the sarcasm). But enough with the mini-rant; let’s see what connection GWG has with offspring obesity.
The current systemic review included 23 articles, most of which utilized over one-thousand subjects. Total GWG was defined as the difference between the mother’s weight at delivery and her pregnancy weight, and most studies received this data via self-reporting or medical records. Overall, it was found that every kilogram (2.2 lbs) of GWG led to a 3-23% increased risk of the offspring being overweight or obese after adjustments for confounding variables. Now, when looking to the studies involved it appears that the 23% was in children 3-years of age, while all others aged 4-14 years had a risk of 3-8%. Okay, clearly not very “wow” factor, but consider the IOM’s 7 kg recommendation. Even at the lowest risk percent, hitting the recommended weight gain puts the child at 21% increased risk of becoming overweight or obese. Now consider that many women gain more than that. It starts to add up.
On this note, when looking specifically to the results for GWG above the IOM’s recommendation we see that the risk for overweight and obese offspring was between 40-73% in mothers who gained too much weight, and one of the studies comparing the effects of excessive GWG and non-excessive GWG (adequate GWG plus inadequate GWG) on offspring’s risk of being overweight between 5 and 8 years of age found a 73% higher risk in the excessive GWG children. Regarding not gaining enough weight, no study found a risk. In fact, five studies found no association and three studies found an inverse association.
Also, there was a consistent demonstration that the GWG in early- and mid-pregnancy was associated with offspring weight status, while weight gain in late pregnancy showed no such association. For non-overweight women, GWG in the early- and mid-pregnancy phases is primarily fat in the hips, back, and upper thighs which serve as a caloric reservoir for lactation after birth. This alone should demonstrate that your body is primed to lose the fat it gained while you breastfeed. Regardless, mid-pregnancy is also a critical time in offspring development and excessive fat deposition could increase the transmission of fatty acids from the mother to the fetus, not to mention that the excessive fat could and reduce the mother’s insulin sensitivity and glucose tolerance.
So how much weight should I gain?
One of the studies reviewed categorized total GWG into <10, 10–14, 15–19, 20–29, 30–39, and ≥40 lbs. Their findings indicated a U-shape association between total GWG and offspring’s weight status. Using mothers who gained the recommended 15–19 lbs as a reference group, the risk of being overweight at age 18 significantly increased by 51% in the offspring of mothers who gained <10 lbs, by 56% in the offspring of mothers who gained 10–14 lbs, and by 68% in those who gained ≥40 lbs. Thus, it appears that 15-40 lbs of weight gain is a safe bet, but when taken in the context of the other studies it becomes prudent to stay closer to 15 lbs.