NIH-funded research finds reduced risk of complications for mother and baby
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Mr. Barrett Whitener: It's normal for most women to gain weight during pregnancy, but gaining too much weight can pose serious health risks for mother and baby. Now researchers funded in part by the National Institutes of Health have found that an integrated program offering support and nutrition counseling succeeds where the traditional approaches failed and helps keep women from adding too much weight during pregnancy.
From the National Institutes of Health, I'm Barrett Whitener. This is "Research Developments," a podcast from the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development, the NICHD.
With me today is study author Kim Vesco of the Kaiser Permanente Center for Health Research in Portland, Oregon.
Risk of complications from weight gain during pregnancy are greater for women who are already obese when they get pregnant. For the mother, excessive weight gain during pregnancy is linked to a serious condition called preeclampsia, which can cause dangerously high blood pressure. Gaining too much weight can also lead to gestational diabetes.
Babies born to women who gain too much weight during pregnancy are more likely to have shoulder dystocia, a condition in which the shoulders are wider than the head. This can make natural birth more difficult and may require a caesarean delivery. Also, babies born with extensive body fat are themselves at risk for obesity later in life, as well as for such complications of obesity as heart disease and diabetes. Thank you for joining us today, Dr. Vesco.
Dr. Kim Vesco: Thank you for inviting me.
Mr. Whitener: How much weight gain is usually considered healthy versus unhealthy for obese women who are pregnant?
Dr. Vesco: For obese women who are pregnant, the weight gain recommended for pregnancy is 11 to 20 pounds. That is the weight gain recommended by the Institute of Medicine. There are also weight gain recommendations for women who are considered normal or overweight, and they differ from those for women who are obese. For women who are overweight, it's 15 to 25 pounds, and for women who are normal weight, it's 25 to 35 pounds.
Mr. Whitener: Can you tell us why you thought the approach you used might help the obese women in your study avoid gaining an unhealthy amount of weight?
Dr. Vesco: I think there were several techniques that we used in our intervention that helped women limit their weight gain. In our study, we asked the women to follow a healthy diet based on the DASH eating pattern, which is high in fruits and vegetables and includes lean meats, lean proteins like chicken, fish, and low-fat beef, and then whole grains. We also ask women to reduce their consumption of sweets and sweetened drinks.
And then we gave them techniques to track their dietary intake, so we asked that they keep daily food records, which helps them be accountable to their dietary goals and keep an idea of what they've eaten through the day as they go through the day.
We also ask them to show those food records to the interventionist or the women who led the weekly meetings that they attended during their pregnancy. And then as part of those weekly meetings, the women in this study were weighed every week. So they had an idea, on a regular basis, of how much weight they'd gained to help them stay within their goal of minimizing their weight gain and literally shooting for weight maintenance.
Mr. Whitener: And I believe, as you note in the study, that it had been found in previous work that for non-pregnant adults, this kind of approach was helpful in aiding them in losing weight and also helpful for obese, non-diabetic pregnant women.
Dr. Vesco: Yes, the studies in the non-pregnant adults suggest that the weekly group meetings with the accountabilities and keeping food records can help with weight loss and weight maintenance. I think the accountability part is very important, because then women can set goals—whether they're pregnant or non-pregnant—set goals. In our study, it was to not gain weight. In someone who is not pregnant, it might be to lose weight.
But they set that weight gain goal and dietary goals, and then they have accountability to themselves with their food records, and also to other people in their group by doing weekly weight checks, and sharing their food records, and sharing their progress toward the goals that they set.
Mr. Whitener: Now, I mentioned in the introduction that this approach could possibly also help to reduce the proportion of babies born to these women who are large for their gestational age, as you put it in the study. Can you help us understand what it means to say a baby is large for its gestational age?
Dr. Vesco: For a baby that's large for gestational age, it means it's bigger than 90 percent of the babies at the same gestational age and gender. So, for example, a baby boy born at 40 weeks would be considered large for his gestational age if he weighed more than 9 pounds 3 ounces. And that's important because larger babies are more at risk for having delivery complications, getting stuck in the birth canal, you mentioned earlier shoulder dystocia, which is a consequence of the head coming out but the shoulders, the upper body, being too large to easily come out once the head delivers.
These larger babies are also more at risk for having low blood sugar after delivery and needing to have medical therapies to raise their blood sugar. And then larger babies are also at risk later in life for obesity and the complications of obesity, as you mentioned earlier, such as diabetes.
Mr. Whitener: Now, there was a comparison group that you also studied, or a control group. What steps did that group take to reduce their weight gain during pregnancy?
Dr. Vesco: So for our control group, they met with our study dietitian one time, and went over food records, and received general advice about healthy eating in pregnancy, and then the rest of their pregnancy was advice that they would obtain from their OB care provider. So we did not provide any additional advice or weight monitoring for women in the control group.
Mr. Whitener: And there was also none of the group interaction or shared experiences with the control group?
Dr. Vesco: Right. So they would not have participated in the weekly group meetings as the women in the intervention group did.
Mr. Whitener: So what differences did you find between the two groups during the study and at the end?
Dr. Vesco: So we followed the women during their pregnancy and asked them to come back late in their pregnancy, around 34 weeks gestation, to check their weight gain. And then we asked them to come back after delivery, around two to three weeks post partum, to weigh them and to measure and weigh their babies.
We found that women in the intervention group gained an average of 11 pounds by 34 weeks gestation, compared to 18 pounds for women in the control group. So there was significantly less weight gain in the women in the intervention group.
And then after delivery, at two to three weeks after delivery, women in the intervention group weighed about six pounds less than they did when they entered the study, compared to women in the control group, who weighed about three pounds more than they did when they entered the study. And that difference was significant.
One thing I do want to point out, though, is both groups of women, by joining the study, were probably fairly motivated to have healthier weight gain. So the average weight gain for both groups was within the Institute of Medicine guidelines at 34 weeks gestation.
Mr. Whitener: Were there any differences overall between the babies that were delivered in each group?
Dr. Vesco: There was no difference in the average birth weight between the babies in the two groups; however, the women in the intervention group were less likely to have a large-for-gestational-age baby. That means a baby that's bigger than 90 percent of other babies of its gender and gestational age.
So the women in the intervention group, about 9 percent of them, had a baby that was large for gestational age, compared to 26 percent of women in the control group.
Mr. Whitener: Where does this research go next?
Dr. Vesco: I think some of the next steps would be first doing larger studies like ours to confirm the health benefits of limiting weight gain for obese women, and also to confirm that there aren't any risks to this approach.
Also, I think it's important to work within our health care system to try to figure out how to implement these effective strategies to help, really, all pregnant women keep their weight gain within recommended range.
While our study focused on obese women, excessive weight gain is really a problem for normal and overweight women as well. While we wouldn't potentially—while we wouldn't ask those women to limit their weight gain to weight maintenance, we would like them to have healthy weight gain within the Institute of Medicine recommendations. And several of the techniques that we use with the women in our study would be helpful for women who are normal weight and overweight as well.
Mr. Whitener: I've been speaking with Dr. Kim Vesco, lead author of the study, "Efficacy of a Group-Based Dietary Intervention for Limiting Gestational Weight Gain Among Obese Women: A Randomized Trial," which was published in the journal Obesity.
Dr. Vesco, thanks so much for joining us.
Dr. Vesco: Thank you.
About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute's website at http://www.nichd.nih.gov/.