Influence of Pregnancy Weight on Maternal and Child Health: Workshop Report (2007)

Workshop participants focused explicitly on insights from interventions to promote appropriate maternal weight during pregnancy and postpartum. Such interventions include individual approaches to change behaviors related to appropriate weight, psychosocial factors that affect weight, community approaches to promote weight management, and practices and policies for clinicians and health systems. The presenters focused their review on interventions to control excessive gestational weight gain. This focus is a reflection of the recent research efforts in this area. In addition to the presentations on determinants of gestational weight gain summarized in Chapter 3, the approaches described in this chapter may help guide Title V maternal and child health programs to assist women of childbearing age to achieve and maintain recommended weight before, during, and after pregnancy.

Rena Wing presented an overview of strategies to encourage appropriate weight gain during pregnancy. The key times for intervention efforts are during pregnancy, to prevent excessive weight gain during pregnancy, and the postpartum period.

Researchers and practitioners know a great deal about weight management: in order to change their weight, people need to change their energy

balance through a combination of caloric restriction and physical activity. Physical activity, although very important for the maintenance of weight loss, actually has a smaller impact on actual production of weight loss. In studies looking at the role of physical activity alone or in combination with diet, physical activity is responsible for only a 2 to 4 lbs. weight change. To lose weight, many individuals need help to change their behaviors, by using such techniques as goal-setting, receiving feedback on the changes, self-monitoring or writing down information, stimulus control (changing the environment they live in), and problem solving. Merely educating individuals about how much to eat and how much to exercise is not sufficient.

Olson and Strawderman (2003) surveyed 458 pregnant women and asked about changes in their diet and exercise behaviors during their pregnancy. This prospective cohort study followed women from early pregnancy until two years postpartum. Of these women, 41 percent exceeded the 1990 Institute of Medicine (IOM) recommendations for weight gain. Individuals who reported eating much more food during pregnancy than before had a more than twofold risk of exceeding the weight recommendations, and those who reported less physical activity than before pregnancy had a 1.75 relative risk of exceeding the IOM recommendations.

In the study of Icelandic women by Olafsdottir et al. (2006), 34 percent of the women exceeded the IOM recommendations. One of the strongest predictors of doing so was their self-reported caloric intake; women who exceeded IOM recommendations reported consuming 2,186 calories per day, about 300 calories more per day than those with optimal gestational weight gain. This study also reported that increased intake of sugar and fat was related to increased risk of excessive gestational weight gain.

Several studies found that caloric intake and caloric expenditure are related to postpartum weight retention. In Olson and Strawderman’s data (2003), 25 percent of the women retained 10 lbs. or more. Individuals who reported increasing food intake during the second 6 months had a more than threefold risk of greater weight retention at the end of the year, and those who reported exercising often actually had a decreased risk of high postpartum weight retention. These studies suggest that the key behaviors to focus on both during pregnancy and afterward are eating and physical activity behaviors that have an impact on energy balance.

Polley et al. (2002) conducted a randomized control trial to prevent excessive gestational weight gain with 120 women with low-risk pregnancies. The women were enrolled at less than 20 weeks gestation, with body mass index (BMI) greater than 19.8. The control group received the usual care during their pregnancy, while the intervention group received written and oral information about appropriate gestational weight gain, exercise, and healthy eating during pregnancy. They received biweekly newsletters emphasizing these three messages. Both the control and intervention groups include black (39 percent) and non-Hispanic white (61 percent) women who were considered of normal weight (54 percent) or overweight or obese (46 percent). All women in the intervention received goal-setting assistance and feedback. If women continued to exceed the gestational weight gain goal, they received either face-to-face counseling at their clinic visits or phone-based counseling. They also received increasingly structured behavioral goals, both for physical activity and for diet. The study was statistically effective for the normal-weight women; in the control group, 58 percent of the women exceeded the IOM recommendations versus 33 percent in the intervention group. In the overweight group, there was no statistically significant difference.

This intervention during pregnancy showed effectiveness at preventing excessive weight gain in normal-weight women. There was a strong correlation between weight gain during pregnancy and weight retention 1-year postpartum in normal-weight women, arguing for interventions during the pregnancy period to prevent weight retention 1-year postpartum.

There are advantages and disadvantages to intervening during pregnancy. One major advantage of intervening at this time is that excessive weight gain during pregnancy is one of the strongest predictors of subsequent obesity and problems with postpartum weight retention. The major disadvantage to intervening at this time involves psychological concerns about the mother as well as concerns about the developing baby. Interventions to control weight during pregnancy must avoid any potential for harm to the fetus.

Another strategy is to intervene in the postpartum period, allowing the woman to gain what she wants and then dealing with it later. Leermakers et al. (1998) performed a small study of reducing postpartum weight retention. The researchers developed a correspondence intervention targeted at

women (97 percent non-Hispanic white) who had delivered within the past 3 to 7 months and who were exceeding their prepregnancy weight by 15 lbs. with a BMI greater than 22 (on average they were exceeding by 27 lbs.).

The women were randomly assigned to a 6-month behavioral treatment through correspondence or a no-treatment control. The correspondence program began with two face-to-face group meetings and continued with 16 weeks of correspondence intervention: behavioral lessons were sent to the women, they completed homework, and they received telephone contact to reinforce progress. The women also followed a 1,000 to 1,500 calorie/day diet. They were encouraged to be physically active and to increase their activity by walking two miles a day five days a week. The no-treatment control group received only informational brochures.

On average the women in the correspondence group lost 17 lbs. over the 6 months compared with 10 lbs. in the control group, a statistically significant difference. About a third of the women in the intervention group returned to their prepregnancy weight, compared with about 11 percent of the controls.

Intervening during the postpartum period can be intensive and involve strict diet and more physical activity. This is an advantage that interventions during pregnancy do not have. There are generally fewer concerns about safety, especially for the child. A disadvantage of postpartum interventions is that it is clearly a burden for new mothers; there was a 31 percent attrition rate in the Leermakers et al. (1998) study. In another study of postpartum weight retention interventions (e.g., O’Toole et al., 2003), only 23 of the 40 women finished the program.

Wing observed that opportunities for interventions exist before pregnancy, during pregnancy, and postpartum, although the literature reviewed included only interventions during pregnancy and postpartum. Setting goals for weight, eating, and activity in addition to feedback for meeting these goals are key components of this type of intervention. Exercise alone and changing the quality of the diet alone do not show an effect of weight loss postpartum.

Lorraine Walker presented research on psychosocial factors that could affect appropriate weight during pregnancy and postpartum. According to Kramer et al. (2000), psychosocial variables may be mediators of psychosocial disparities in a society, and they may also be antecedents of pathways for changes in physical activity and diet. Although many psychosocial fac-

tors may play a role in gestational weight gain, four seem especially important: stress, social support, depression, and attitude. Another factor, infant feeding practices (reviewed in Chapter 4), includes duration of breastfeeding and postpartum weight retention. The literature in these areas is predominantly observational research, often exploratory, rather than theory- or hypothesis-driven.

High stress can have an adverse effect on gestational weight gain, either through behavioral pathways that often are not fully specified or biological pathways leading to inadequate or excessive gestational weight gain. The relationship between stress and BMI is curvilinear, not linear. The literature suggests that stress has different kinds of effects depending on a person’s response, an effect also seen with respect to depression. For stress in relation to gestational weight gain, the findings are mixed; different subgroups had positive, negative, or no effects. A few studies indicated that stress was associated with lower gestational weight gain (Brawarsky et al., 2005; Campbell et al., 1999; DiPietro et al., 2003; Hickey et al., 1995; Johnson et al., 2002; Orr et al., 1996; Parker et al., 1994; Picone et al., 1982; Siega-Riz and Hobel, 1997; Stevens-Simon and McAnarney, 1992, 1994; Wells et al., 2006). Stress in these studies includes stressful life events, chronic stress, hassles, or perceived stress in addition to physical or sexual abuse during pregnancy. The lack of consensus on the stress measures challenges comparability of the studies.

Social support is typically seen as having a beneficial effect, although the behavioral or biological pathways are not clearly articulated. Social support may have a buffering effect, in that it may cancel the effects of stress on gestational weight gain. However, studies on social support show mixed results, depending on the analysis (DiPietro et al., 2003; Hickey et al., 1995; Olson and Strawderman, 2003; Siega-Riz and Hobel, 1997; Stevens-Simon and McAnarney, 1992). Social support was measured in a variety of ways, including total support, partner support, emotional support, financial support, and network size. None of these studies looked at the possible interaction of social support and stress, although an early study done by Nuckolls et al. (1972) found that women with high stress and low social support had less favorable pregnancy outcomes.

Maternal depression is usually assessed by an interview administered by a health professional using diagnostic criteria. Most epidemiological studies use a questionnaire that has a cutoff score, such as the Edinburgh Postnatal Depression Scale or the Center for Epidemiologic Studies Depression Scale. Depression is hypothesized to have an adverse effect on gestational weight gain through behavioral or biological pathways, which may lead either to inadequate or excessive gestational weight gain.

About half of the studies looking at a relationship between depression and pregnancy outcomes reported no effect; the remainder indicated mixed effects for subgroups or different associations between high and low gestational weight gain (Brawarsky et al., 2005; DiPietro et al., 2003; Hickey et al., 1995; Siega-Riz and Hobel, 1997; Stevens-Simon and McAnarnery, 1992; Walker and Kim, 2002; Zuckerman et al., 1989). None of the studies looked at the curvilinear relationship between depression and gestational weight gain.

Attitudes are another factor that has been studied in relation to gestational weight gain. Attitudes may relate to either an increase or a decrease in health-promoting or health risk behaviors and may lead to excessive or inadequate gestational weight gain. These factors include attitudes toward pregnancy or weight gain during pregnancy, self-efficacy, motherhood, and career. The results of these studies on attitudes affecting gestational weight gain are mixed; the effects may be seen in one subgroup but not in another (Copper et al., 1995; DiPietro et al., 2003; Olson and Strawderman, 2003; Palmer et al., 1985; Stevens-Simon et al., 1993). One study found that more positive attitudes were related to higher gestational weight gain, but further testing on a more diverse sample showed that negative attitudes toward gestational weight gain were related to more weight gain as well. A critical shortcoming in this area is measurement.

Data available in some state service models (e.g., California, Colorado) are potential sources of information on the efficacy of psychosocial interventions on promoting appropriate gestational weight gain (Ricketts et al., 2005; Zimmer-Gembeck and Helfand, 1996). In these models, the researchers examined whether or not someone has actually received a psychosocial intervention, whether or not that psychosocial problem has been resolved, and the outcome. Many of those studies may not have gestational weight gain as one of their outcomes.

The relationship of psychosocial factors and postpartum weight retention was studied. Studies on psychosocial factors and postpartum weight retention are limited to exploratory (rather than theory-driven), primarily observational, studies. Four studies have addressed the area of stress, social support, depression, and their relationship to postpartum weight retention (Walker, 1996, 1997; Walker and Freeland-Graves, 1998; Walker et al., 2004). The studies found no support for the relationship between stress and a high retained weight postpartum. There was some evidence of a relationship between social support and a decrease in retained weight postpartum. The data were split (one study finding a relationship of high retained weight and one finding no effect) regarding the relationship of depressive symptoms and retained weight. In addition, four studies have addressed the effect of attitudes on postpartum weight retention (Walker, 1996; Walker and Grobe, 1999; Walker and Freeland-Graves, 1998; Walker et al., 2004). The attitude variables included weight-related distress (an attitude of dissatisfaction toward one’s body image), the pros and cons of weight loss, and the locus of control. Looking at these studies, locus of control was unrelated to postpartum weight retention, and weight-related distress was positively related to a higher gestational weight gain.

Although the evidence on how psychosocial factors relate to weight both during pregnancy and postpartum is inconsistent, the impact of psychosocial factors may be underestimated because of measurement and data analytic issues. Future research could provide a better foundation for examining psychosocial factors, with model-driven tests of the impact of psychosocial factors on gestational weight gain and postpartum weight retention, which could build in some of the behavioral components.

Christine Olson presented data from a few studies on the effects of community or multilevel interventions to promote appropriate weight during pregnancy and postpartum. Peterson et al. (2002) describe important features of community interventions addressing multiple levels of influence on diet, physical activity, and weight loss in postpartum women. Their design included a sustained, multiple-component intervention with home visits by a mentor, who targets awareness of weight issues and nutrition, motivation, skill building, and building social support; group classes that reinforce the project messages by teaching and demonstrating

some skills as well as fostering social interactions; and telephone counseling. Only two studies are available to provide insight into the effects of these interventions.¹

The first published community intervention study (Gray-Donald et al., 2000) focused on reducing weight gain in pregnancy as a way to prevent gestational diabetes in indigenous communities in Canada. This prospective study, with an 8-month control period followed by a 9-month intervention period, was implemented in four Cree communities in Quebec. The intervention was offered by nutritionists and native health workers. Its design was based on social learning theory and included modeling of the behavior change, skill training, contracting, and self-monitoring. The types of activities the investigators carried out in the community include radio broadcasts, information pamphlets, supermarket tours and cooking demonstrations, exercise walking groups, and individualized nutrition counseling.

The study results indicated no statistically significant differences between the control and intervention groups in such outcomes as weight gain during pregnancy, plasma glucose, and weight and weight retention at 6 weeks postpartum. The results of this study could be confounded with cultural norms of Cree communities; physical activity is not considered appropriate during pregnancy, and being plump is normal.

The second intervention study, Staying in the Range, sought to decrease weight retention at 1-year postpartum by promoting appropriate gestational weight gain in a health care system in Cooperstown, New York (Olson et al., 2004). The goal was to decrease (by 50 percent) the proportion of normal and overweight BMI women who exceeded the upper limit of the 1990 IOM gestational weight gain recommendations (Institute of Medicine, 1990). This prospective cohort study included a historical control group from an observational study with usual care in pregnancy and an intervention group. The intervention group was followed from early pregnancy through a postpartum period with measures of gestational weight gain and weight retained at 1-year postpartum. The design of the intervention included health care providers monitoring weight gain using adapted IOM gestational weight gain grids. The pregnant women received five motivational action-promoting newsletters and postcards focusing on their gestational weight gain, diet, and physical activity, and they also received a

health checkbook for goal-setting and self-monitoring. The process evaluation indicated most women engaged with the postcards, setting appropriate gestational weight gain goals.

Based on the data collected, the intervention had a statistically significant effect on decreasing excessive gestational weight gain in the low-income women only. A three-way interaction among income, treatment, and BMI was found on postpartum weight retention. In addition, reduced weight retention was seen at 1-year postpartum for the overweight low-income women.

Laura Riley highlighted factors of health care and of the health care system that could promote or hinder the compliance of recommended gestational weight guidelines prior to, during, and after pregnancy. There is scant literature on this topic. Riley focused on the recommended practices and policies that are available for clinicians in promoting appropriate weight prior to, during, and after pregnancy. She closed her presentation with personal clinical experiences.

The American College of Obstetrics and Gynecology (ACOG) issues short committee reports with specific recommendations as well as the underlying science and data. Reports from the OB Practice Group and the GYN Practice Group give guidelines on addressing obesity in pregnancy for obstetricians, gynecologists, and other health professionals or paraprofessionals, and highlight the role of the obstetrician and gynecologist in the assessment and management of obesity.

The OB Practice Group (American College of Obstetricians and Gynecologists, 2005) presented a strong argument that obstetricians should provide preconception counseling and education about the complications that may be faced by obese patients and encourage these patients to undertake a weight reduction program before attempting pregnancy. Suggestions include recording patients’ height and weight; offering nutrition counseling; and screening for gestational diabetes earlier in pregnancy than the standard 28 weeks gestation.

Other parts of the ACOG guidelines include anesthesia consultation, which is important for obese women, who have higher rates of cesarean delivery and other complications. The report also includes discussion on antibiotic prophylaxis; postoperative complications specific to the obese

population; and fetal monitoring challenges. Finally, since more women are having bariatric surgery prior to pregnancy, ACOG guides obstetricians on the differences in their pregnancies.

Another ACOG report, issued by the GYN Practice Group, is equally important for the topic of this workshop. The GYN Practice Group issued guidelines on the assessment and management of obesity in nonpregnant women, which is important to clinicians who provide preconception care (American College of Obstetricians and Gynecologists Committee on Gynecologic Practice, 2005). It stresses calculating BMI and then offering overweight patients appropriate interventions or referrals to promote healthy weight and lifestyle. The report also provided information about patients who may benefit from pharmacotherapy or for whom a consultation about surgery should be considered.

Another ACOG committee on adolescent health care has decided to review issues specific to overweight adolescents. They are pulling together data concerning prevention, treatment, and obstetric as well as gynecological implications. This will provide preconception information for young women as well as for those who experience unintended pregnancies.

The Guidelines for Perinatal Care (5th edition) addresses some of the issues with obesity and includes the IOM recommendations for weight gain during pregnancy (American Academy of Pediatrics and American College of Obstetricians and Gynecologists, 2002). The 6th edition will include an expanded discussion about appropriate weight gain and the potential implications of obesity in pregnancy. Guidelines for Women’s Health Care (2nd edition) includes a discussion about weight gain, healthy lifestyle, and healthy eating (American College of Obstetricians and Gynecologists, 2002).

Other professional organizations are providing similar guidance. The American Academy for Family Physicians does not have specific documents similar to the ACOG committee reports; however, its web site provides information for members about screening and advises physicians to screen all adult patients for obesity and to offer intensive counseling and behavioral interventions to promote sustained weight loss for obese adults.

The American College of Midwives expresses interest in the topic. Although they do not currently have resources to produce their own document, they encourage the use of the IOM recommendations and reprint them in various places. They have conducted two major educational series that included the topic of obesity through lectures at their annual meetings, one of which was published in their journal.

Do these professional efforts make a difference in terms of how providers treat their patients? ACOG administered a survey to a random sample of practitioners one year before its committee reports were issued (prior to 2004) to test practitioner knowledge about obesity, as well as to determine practice patterns before the committee reports were released. A second, one-year postcommittee opinion survey has been distributed, but data are not yet available.

Following the OB Practice Group’s report on obesity in pregnancy, Riley investigated the obstetrician patient population of Massachusetts General Hospital. Although the ACOG reports target individual practice, large health care systems can also change their practice based on these guidelines. A preliminary review of 3,500 obstetric patients through electronic medical records revealed that 40 percent of the patient population was overweight or obese at the time of their first prenatal visit. Hispanic and black women had the highest rates of obesity and overweight. A total of 54 percent of the population was overweight or had obesity at their postpartum visit, which is generally 6 to 8 weeks postpartum. About 25 percent of women gained more than 35 lbs. during their pregnancy.

All providers received a paper about the impact of obesity on health that focused on pregnancy and issues surrounding childbirth, including both maternal and fetal complications. This information was most helpful to the nurses, who do a fair amount of patient education. Massachusetts General is planning to conduct focus groups to learn more about obesity and pregnancy. They want to understand the relevance to the clinicians’ practice, how to understand the patients’ perception of the problem, what interventions would work best in each particular group, and how to support patients as well as clinicians.

From a practice perspective, a number of practical considerations arise in moving toward implementation of the ACOG recommendations. Concerns include availability and cost of nutrition counseling; the number of obese women who will seek preconception counseling; and payment for preconception counseling. The practice pattern of internal medicine physicians concerning preconception counseling for obese women needs to be understood. Finally, there is a need for more research on the effectiveness of intervention efforts for this specific population.

Interventions to promote appropriate weight during pregnancy and postpartum include individual (behavior), psychosocial, community, and health care and health care system approaches. Studies on the design or impact of interventions delivered before pregnancy to promote appropriate weight gain during pregnancy are not available. The presenters focused their review on interventions to control excessive gestational weight gain, consistent with recent research efforts in this area.

Individual approaches to change behavior are based on achieving an energy balance between diet and physical exercise. Studies have focused on interventions to limit excess weight gain during pregnancy and weight retention in the postpartum period. Behavioral strategies include goal-setting, feedback, self-monitoring, stimulus control, and problem solving. Psychosocial factors may affect appropriate weight during pregnancy and postpartum as well. These factors include stress, social support, depression, attitudes, and infant feeding practices. The studies that investigate the effect of these factors on pregnancy-related weight are inconsistent in their findings; all are observational studies with methodological problems that make it difficult to interpret them.

A community-based intervention is based on a multilevel sustained approach to promote appropriate gestational weight gain and reduce postpartum weight retention. The study design can include home visits, social support, group classes, goal-setting, skill training, self-monitoring, and feedback. Compared with individualized approaches, community-based programs may be a less expensive approach with low clinician burden. Finally, no studies exist on clinician or health care and health care system–based interventions to improve pregnancy-related weight gain. Practice guidelines available for obstetricians and gynecologists include assessment and management of obesity and pregnancy, as well as interventions for women with a history of bariatric surgery. However, the guidelines are not likely to be implemented in isolation; evidence on the effectiveness of behavioral interventions suggests that behavioral modification components will be necessary to add to the guidelines so that health providers can offer more comprehensive or additional support to women during prepregnancy and perinatal periods.

It is important that approaches to achieve and maintain recommended weight before, during, after, and between pregnancies are investigated. The appropriate approach may vary by subgroup. Studies on interactions of variables, prepregnancy BMI and gestational weight gain, race/ethnicity and gestational weight gain, and socioeconomic status and gestational weight gain are needed. A combination of these approaches, at the individual and the environmental levels, may be required for women to achieve

and maintain recommended weight before, during, and after pregnancy. Indeed, integration of weight management into a healthy lifestyle is a critical goal.

In addition to these approaches (individual, psychosocial, community, and clinician and health system), the presentations on determinants of gestational weight gain in Chapter 3 offer insight for Title V maternal and child health programs to help women of childbearing age to achieve and maintain recommended weight before, during, and after pregnancy.

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