A study analysing the weight gain during pregnancy of mothers with more than one child shows that pregnant women who put on more weight are much more likely to have heavier babies. Given the association of birthweight with adult weight, the authors of this new work say that obesity prevention efforts targeted at women during pregnancy could have beneficial effects for their children. The Article, published Online First in The Lancet, is written by Dr David S Ludwig, Children’s Hospital, Boston, MA, USA, and Dr Janet Currie, Columbia University, New York, USA.
While other work has shown that excessive weight gain during pregnancy seems to increase birthweight (and the offspring’s risk of obesity later in life), this association might be confounded by genetic and other shared effects. Thus in this study, the authors analysed multiple single pregnancies in the same mother, so that the genetic element could be excluded. The authors used US-state-based birth registry data that allowed this comparison. All known births in Michigan and New Jersey, USA, between Jan 1, 1989, and Dec 31, 2003, were studied. From the sample of women selected, the following exclusions were made: gestation less than 37 weeks or 41 weeks or more; maternal diabetes; birthweight less than 500 g or more than 7000 g; and missing data for pregnancy weight gain.
The final analysis included 513 501 women and their 1 164 750 offspring. A consistent association between pregnancy weight gain and birthweight was shown, with each kg gained by the mother in pregnancy increasing the baby’s birthweight by 7.35 g. Infants of women who gained more than 24 kg during pregnancy were around 150g heavier at birth than were infants of women who gained 8-10 kg. Women who gained more than 24 kg during pregnancy were more than twice as likely to give birth to a child weighing 4 kg or more compared with women who gained 8-10 kg.
The authors conclude:
Because high birthweight predicts BMI later in life, these findings suggest that excessive weight gain during pregnancy could raise the long-term risk of obesity-related disease in offspring. High birthweight might also increase risk of other diseases later in life, including asthma, atopy, and cancer.
In a linked Comment, Dr Neal Halfon and Dr Michael C Lu, Center for Healthier Children Families Communities, University of California, Los Angeles, CA, USA, say:
Although a better understanding of the effect of gestational weight gain on the developing fetus and metabolic functioning of the newborn child is important, research is urgently needed into how to help women of reproductive age attain and maintain a healthy weight before and during pregnancy. With a growing focus on preconceptional health, there is an opportunity to develop effective interventions to help women conceive at a healthier weight. More effective population-based strategies are needed to produce healthier life-long weight trajectories, and to interrupt the cross-generational cycle of excessive weight gain.
“The association between pregnancy weight gain and birthweight: a within-family comparison”
David S Ludwig, Janet Currie
The Lancet August 5, 2010. DOI:10.1016/S0140-6736(10)60751-9
Source: The Lancet
