Women who gain more fat during pregnancy may not have bigger babies: implications for recommended weight gain during pregnancy

Rate of gestational weight gain trajectory is associated with adverse pregnancy outcomes

OBJECTIVE

To examine the gestational weight gain (GWG) trajectory and its possible association with pregnancy outcomes.

DESIGN

GWG trajectories were identified using the latent class growth model. Binary logistic regression was performed to examine the associations between adverse pregnancy outcomes and these trajectories.

SETTING

Negeri Sembilan, Malaysia.

PARTICIPANTS

Two thousand one hundred ninety-three pregnant women.

RESULTS

Three GWG trajectories were identified: 'Group 1 - slow initial GWG but followed by drastic GWG', 'Group 2 - maintaining rate of GWG at 0·58 kg/week' and 'Group 3 - maintaining rate of GWG at 0·38 kg/week'. Group 1 had higher risk of postpartum weight retention (PWR) (adjusted OR (AOR) 1·02, 95 % CI 1·01, 1·04), caesarean delivery (AOR 1·03, 95 % CI 1·01, 1·04) and having low birth weight (AOR 1·04, 95 % CI 1·02, 1·05) compared with group 3. Group 2 was at higher risk of PWR (AOR 1·18, 95 % CI 1·16, 1·21), preterm delivery (AOR 1·03, 95 % CI 1·01, 1·05) and caesarean delivery (AOR 1·02, 95 % CI 1·01, 1·03), but at lower risk of having small-for-gestational-age infants (AOR 0·97, 95 % CI 0·96, 0·99) compared with group 3. The significant associations between group 1 and PWR were observed among non-overweight/obese women; between group 1 and caesarean delivery among overweight/obese women; group 2 with preterm delivery and caesarean delivery were only found among overweight/obese women.

CONCLUSIONS

Higher GWG as well as increasing GWG trajectories was associated with higher risk of adverse pregnancy outcomes. Promoting GWG within the recommended range should be emphasised in antenatal care to prevent the risk of adverse pregnancy outcomes.

The relationship between gestational weight gain and fetal growth: time to take stock?

The aim of this article is to review the current evidence on gestational weight gain (GWG). Maternal obesity has emerged as one of the great challenges in modern obstetrics as it is becoming increasingly common and is associated with increased maternal and fetal complications. There has been an upsurge of interest in GWG with an emphasis on the relationship between excessive GWG and increased fetal growth. Recent recommendations from the Institute of Medicine in the USA have revised downwards the weight gain recommendations in pregnancy for obese mothers. We believe that it is time to take stock again about the advice that pregnant women are given about GWG and their lifestyle before, during, and after pregnancy. The epidemiological links between excessive GWG and aberrant fetal growth are weak, particularly in obese women. There is little evidence that intervention studies decrease excessive GWG or improve intrauterine fetal growth. Indeed, there is a potential risk that inappropriate interventions during the course of pregnancy may lead to fetal malnutrition that may have adverse clinical consequences, both in the short- and long-term. It may be more appropriate to shift the focus of attention from monitoring maternal weight to increasing physical activity levels and improving nutritional intakes.

Factors Influencing Desired Postnatal Weight Loss in Women after Birth

PURPOSE

The purpose of this study was to identify factors influencing desired postnatal weight loss in women after birth.

METHODS

With correlational survey design, 191women of the study participants completed questionnaires on their desired postnatal weight loss and related factors, and body and health concerns during their hospitalization after birth. Data were collected from February to May, 2011. Data were analyzed using t-test, ANOVA, Pearson correlation coefficients, and multiple linear regression.

RESULTS

The women's gestational weight gain, pre-pregnant BMI, body concerns, expected time to reach the desired weight after birth and health concerns were identified as factors influencing desired postnatal weight loss in women after birth. The model explained 68% of the variance.

CONCLUSION

Results suggest that nurses in women's health care should consider women's gestational weight, pre-pregnant BMI and their body concerns, health concerns and expected time to reach the desired weight after birth when developing weight management program for women after birth.

Influence of dietary intake during gestation on postpartum weight retention

OBJECTIVE

To evaluate the influence of dietary intake during gestation on postpartum weight retention.

METHODS

A total of 82 healthy pregnant women who began prenatal care at public healthcare services in the Municipality of São Paulo (Southeastern Brazil) between April and June 2005 were followed up. Weight and height were measured in the first interview (up to 16 weeks of gestation) and the weight measure was repeated during a household visit 15 days after delivery. The 24-Hour Dietary Recall method was employed to evaluate dietary intake at the three trimesters of gestation. The mean ingestion of saturated fat, fibers, added sugar, soft drinks, processed foods, fruits and vegetables, as well as the dietary energy density were calculated. Weight retention was estimated by the difference between the measure of the postpartum weight and the first measured weight. The influence of dietary intake on postpartum weight retention was assessed by multiple linear regression analysis and the linear trend test was performed. The variables used to adjust the model were: body mass index at the beginning of gestation, height, per capita family income, smoking, age, and level of schooling.

RESULTS

The mean body mass index at the beginning of gestation was 24 kg/m² and the mean weight retention was 1.9 kg. The increase in saturated fat intake (p=0.005) and processed foods ingestion (p=0.014) significantly increased postpartum weight retention, after adjustment by the control variables. The other dietary intake variables did not present a significant relationship to the outcome variable.

CONCLUSIONS

The increased intake of unhealthy food, such as processed foods, and of saturated fat influences the increment of postpartum weight retention.

Pre-pregnancy and pregnancy predictors of obesity

Obesity has progressively become a global epidemic that constitutes one of the biggest current health problems worldwide. Pregnancy is a risk factor for excessive weight gain. Factors that may predict development of obesity in later life mainly include gestational weight gain, pre-pregnancy nutritional status, age, parity and race. Change in lifestyle factors, such as eating habits, enrollment in physical activity, smoking and duration of lactation, in addition to the above factors, may also contribute to the development of obesity but are still not fully understood. Women who retain more body weight after pregnancy have, in general, larger pregnancy body weight gain, higher pre-pregnancy body mass index, marked weight changes in previous pregnancies, lactate slightly less and stop smoking during pregnancy to a larger extent. In addition, irregular eating habits and decreased leisure time activity after delivery influence postpartum weight retention. Taking into consideration the epidemic of obesity, with all its adverse long-term consequences, there is an increasing need to promote counseling before, during and after pregnancy on the role of diet and physical activity in reproductive health.

Pre-pregnancy body mass index among pregnant adolescents: gestational weight gain and long-term post partum weight retention

STUDY OBJECTIVE

To determine the relationship between adolescents' pre-pregnancy body mass index (BMI), and gestational weight gain and postpartum weight retention.

DESIGN

We review the medical records of adolescents participating in a prospective cohort study on comprehensive health care and parenting education to determine pre-pregnancy BMI, gestational weight gain, and postpartum weight retention at one year.

SETTING

Urban academic hospital clinic.

PARTICIPANTS

102 pregnant adolescents aged 15-21 years.

MAIN OUTCOMES

Gestational weight gain and weight retention at one year postpartum.

RESULTS AND CONCLUSIONS

Fifty-two (51%) adolescent women had normal pre-pregnancy BMI according to the Institute of Medicine classification. Adolescent women with normal (36.5%) and high pre-pregnancy BMI (66.5%) were more likely than women with low pre-pregnancy BMI (26.5%) to exceed recommended gestational weight gain. Adolescent women who exceeded recommended weight gain retained significantly more weight at 1 year postpartum than women with weight gain within or below the recommendation. In a linear regression model that controlled for age, smoking, pregnancy complication, and post partum contraceptive use, pre-pregnancy BMI and gestational weight gain were the strongest predictors of postpartum weight retention at 1 year. A normal to high pre-pregnancy BMI and excessive gestational weight gain are important predictors of postpartum weight retention in adolescents. These two predictors must be monitored systematically with the aim of preventing postpartum obesity and its associated diseases among this population.

Assessment of weight changes during and after pregnancy: practical approaches

The usefulness of routine prenatal weight measurements in predicting pregnancy outcomes is still a controversial issue. Comparisons among studies and the interpretation of research findings are complicated due to the variety of indicators applied to express maternal weight changes during and after pregnancy. A review of literature was conducted to clarify the definitions and examine the strengths and limitations of methods for measuring gestational weight gain (WG) and postpartum weight changes. The reasons for weak correlations or non-significant associations between gestational WG and maternal and neonatal outcomes were probably owing to poor quality of obstetrics records and selection of wrong indicators to compute gestational WG. The choice of an indicator depends on clinical and research purpose, availability and reliability of data and cost. Considering the health implication of gestational WG, it is necessary to take into account the measurements used as initial and final weight, accuracy of gestational age estimation and the inclusion of fetal weight as part of maternal WG. Regardless of the indicators used to compute the weight changes after delivery, attention is drawn to the approach for designating prepregnancy weight, the time frame of postpartum weight measurements and the use of overlapping variables, which results in bias (part-whole correlation). It is necessary to address criticisms on the accuracy of prenatal weight measurements and the way of expressing the maternal weight changes during and after pregnancy in order to have reliable results from research.

Do the changes in energy balance that occur during pregnancy predispose parous women to obesity?

The aim of this review was to re-assess whether the changes in energy balance that accompany pregnancy predispose parous women to obesity. A number of cross-sectional studies have sought to answer this question by examining the relationship between parity and maternal body weight. However, these studies were unable to control for the large number of sociobehavioural confounders that might be responsible for the apparent effect of parity on body weight. Longitudinal studies that examine changes in maternal body weight before and after regnancy avoid these problems by using each mother as her own control. Nevertheless, these studies have to overcome three methodological constraints: They must obtain an accurate measure of prepregnant body weight, they must give each mother sufficient time to lose any weight retained following delivery, and they must take into account the effect of ageing on maternal weight gain during pregnancy and the follow-up period. More than 90% of the studies reviewed found body weight to be greater after pregnancy than it was before (by 0.2–10.6kg). and previous researchers who have examined the evidence for pregnancy-related weight gains suggest that body weight increases by an average of 04–4.8kg following pregnancy. However, only three of the 71 longitudinal studies examined in the present review complied with the three methodological criteria. These studies concluded that mothers gain, on average, 0.9–3.3kg more weight following pregnancy than nonpregnant controls, and that mean body weight remained 0.4–3.0kg higher, even after controlling for a number of sociobehavioural confounders. This apparently modest increase in mean maternal body weight for women having one or two children conceals the fact that some mothers experience a substantial increase in body weight and become obese following pregnancy. It remains unclear whether these increases are simply the result of changes in energy metabolism during pregnancy and lactation, or whether they are influenced by inherent changes in lifestyle that accompany pregnancy and motherhood. Understanding the relative importance of these alternatives might help to explain the aetiology of maternal obesity.

“Clover was a stout motherly mare approaching middle life, who had never quite got her figure back after her fourth foal”

George Well (1945) Animal Farm. London: Secker and Warburg.

Trajectory of weight changes in the first 6 weeks postpartum

OBJECTIVE

To determine the trajectory of postpartum weight changes and to examine associations between weight change in the first 6 weeks postpartum and demographic, clinical, psychosocial, and behavioral variables.

DESIGN

Prospective, longitudinal design.

SETTING

Community hospital and university research setting.

PARTICIPANTS

26 low-income women (9 White, 8 Black, and 9 Hispanic) with uncomplicated term pregnancies.

MAIN OUTCOME MEASURE

Body mass index measured weekly.

RESULTS

Among White women, body mass index decreased significantly for the first 3 weeks of the postpartum period. Black women experienced a significant reduction in body mass index for only the first 2 postpartum weeks. Similarly, the postpartum body mass index decreased for the first 2 weeks for Hispanic women. Prepregnancy body mass index and gestational weight gain each had a significant positive effect on postpartum body mass index. Perception of social support at 4 weeks had a significant positive effect on postpartum body mass index in Black women.

CONCLUSIONS

The trajectory of weight change was nonlinear with large initial weight losses during the first 2 to 3 weeks postpartum followed by weight plateaus for the remainder of the first 6 weeks postpartum.

Retention of Pregnancy-Related Weight in the Early Postpartum Period: Implications for Women’s Health Services

OBJECTIVE

To examine the proportion of women who reached their prepregnant weight at 6 weeks postpartum and the average amount of weight retained or lost by this time; to determine predictors of early (6 week) postpartum weight retention; and to propose related implications for women's health care and services.

DATA SOURCES

The literature review was based on a search of Medline for the years 1986 to 2004 using the keywords postpartum weight with inclusion of additional articles known to the authors that did not appear in the electronic search.

STUDY SELECTION

The resulting 83 articles were scrutinized to identify those that reported data on weight retention at 6 weeks postpartum (range, delivery to 3 months) and associated anthropometric, social, obstetric, or behavioral predictors. A total of 12 articles met inclusion criteria for the review.

DATA EXTRACTION

Data were extracted related to the proportion of women achieving their postpartum weight at 6 weeks postpartum, the amount of weight retained or lost up to 6 weeks postpartum, and predictors of amount of weight retained or lost.

DATA SYNTHESIS

On average, at 6 weeks postpartum, women retain 3 to 7 kg of the weight gained during pregnancy, with at least two thirds exceeding their prepregnant weights. Gestational weight gain is the most significant predictor of weight retention.

CONCLUSIONS

Women vulnerable to obesity and weight gain need weight-related health care and improved access to such care to promote weight loss after 6 weeks postpartum.

Weight and behavioral and psychosocial factors among ethnically diverse, low-income women after childbirth: II. Trends and correlates

OBJECTIVE

This paper presents a longitudinal analysis of behavioral and psychosocial correlates of weight trends during the first postpartum year. Data are derived from the Austin New Mothers Study (ANMS), a longitudinal study of a low-income, tri-ethnic sample of postpartum women that incorporated serial assessment of weight and behavioral and psychosocial variables.

METHOD

Postpartum body mass index (BMI) was measured prospectively (post-delivery, 6 weeks, and 3, 6, and 12 months postpartum). The analytic sample consisted of 382 White, African American, and Hispanic women receiving maternity care funded by Medicaid who had at least three measured postpartum weights. Behavioral and psychosocial variables included energy intakes, fat intakes, physical activity, health related lifestyle, smoking, breastfeeding, contraception, depressive symptoms, emotional eating, body image, and weight-related distress.

RESULTS

Using hierarchical linear modeling to incorporate baseline only and time-varying effects, significant associations with postpartum BMI were found for the following variables: ethnicity (p = .001), time of weight measurement (p < .001), the interaction of ethnicity and time (p = .005), pre-pregnant BMI (p < .001), gestational weight gain (p < .001), weight-related distress (p < .001), and energy intakes (p = .005). After adjusting for covariates, ethnic groups displayed differing trends in postpartum BMI resulting in White women having significantly lower BMIs at 12 months postpartum compared to ethnic minority women (p's < .01).

CONCLUSION

Behavioral and psychosocial variables contribute to a fuller understanding of BMI status of low-income women during the first postpartum year.

Weight and behavioral and psychosocial factors among ethnically diverse, low-income women after childbirth: I. Methods and context

OBJECTIVE

In this paper, we present the background, hypotheses, methods, and descriptive findings from the Austin New Mothers Study, a longitudinal series measuring weight and contextual variables across the first postpartum year. Among the distinguishing features of this study are its tri-ethnic sample of low-income women and its serial measurement of the behavioral and psychosocial context of postpartum weight changes post-delivery and at 6 weeks, and 3, 6, and 12 months postpartum.

METHOD

A prospective longitudinal design was used to assess body mass index (BMI), energy intake, fat intake, physical activity, health-related lifestyle, depressive symptoms, body image, and weight-related distress at each observation.

SAMPLE

The analytic sample consisted of 382 White, African American, and Hispanic women.

FINDINGS

For BMI, effects for ethnicity (p < .001), time (p < .001), and their interaction (p = .005) were significant. All ethnic groups had significant declines in BMI from delivery to 6 weeks postpartum. Thereafter, BMIs of White women declined during the second 6 months, whereas those of Hispanic and African American women either displayed small gains or plateaus between adjacent observations. Time-related effects were significant for behavioral and psychosocial variables except for body image and weight-related distress, whereas effects for ethnicity were significant on fat intake, depressive symptoms, and body image. Despite declines in depressive symptoms, women remained at risk of depression across the first postpartum year.

CONCLUSIONS

Low-income ethnic minority women have a higher vulnerability to postpartum weight gains or plateaus. High depressive symptoms occurred in all ethnic groups examined.

Comparative and evolutionary dimensions of the energetics of human pregnancy and lactation

The purpose of this article is to compare the energetics of reproduction for human and other primates in order to evaluate the extent to which human reproductive energetics are distinct from other primates and other large-bodied placental mammals. The article also evaluates the energetics of human and primate gestation and lactation using data from a variety of different populations living under different environmental circumstances. Energetics refers to energy intake and expenditure, and changes in body fat stores. Human and nonhuman primates have longer periods of gestation and lactation and slower prenatal and postnatal growth than other mammals of similar size. This reduces daily maternal energy costs. The development of sizable fat stores is not unique to humans, but fat stores are typically greater in human females and may play a greater role in reproduction. The strategies used to meet the energy costs of pregnancy vary among populations of humans and nonhuman primates and among humans interindividual variability is high. In pregnancy, some increase energy intake but others apparently do not. Increases in metabolic efficiency are evident in some human populations, whereas decreases in physical activity occur, but are not seen in all human or primate populations. Lactation is more energetically costly on a daily basis among humans and nonhuman primates, but has not been as well studied. It appears that both nonhuman and human primates tend to increase energy intake to meet in part the cost of lactation. They also use other strategies such as relying on body tissue stores, reductions in physical activity, and/or increases in metabolic efficiency to meet the remainder of the cost. It is also clear that human females in different populations and different women in the same population use a different combination of strategies to meet the cost of lactation.

Psychosocial thriving during late pregnancy: relationship to ethnicity, gestational weight gain, and birth weight

OBJECTIVE

To test the relationships between psychosocial thriving (depressive symptoms, health-related lifestyle) and gestational weight gain and birth weight. To test the influences of ethnicity on the relationships between psychosocial thriving and gestational weight gain and birth weight.

DESIGN

Baseline data taken from the Austin New Mothers Study.

SETTING

A community hospital in Texas.

PARTICIPANTS

305 low-risk African American, Hispanic, and White women with full-term pregnancies, singleton births, and Medicaid coverage.

MAIN MEASURES

Center for Epidemiologic Studies Depression Scale, Self Care Inventory, Food Habits Questionnaire, gestational weight gain, and birth weight.

RESULTS

Newborns of African American women had lower birth weights (3,240 g) than newborns of Hispanic (3,422 g) or White women (3,472 g), even though no ethnic differences were found among the mothers on psychosocial variables. Late in pregnancy, women had high levels and prevalence (> 70%) of depressive symptoms regardless of ethnicity, and 50% exceeded recommended gestational weight gains. In full regression models, psychosocial variables were not significant predictors of gestational weight gain or birth weight. Ethnicity also was not a significant moderator of weight outcomes.

CONCLUSIONS

Psychosocial thriving late in pregnancy was unrelated to gestational weight gain or birth weight. Ethnicity did not moderate psychosocial-weight relationships. Although ethnic differences were not found on psychosocial variables, high levels of depressive symptoms and greater than recommended gestational weight gains were prevalent. These findings have implications for maternal health during and beyond pregnancy.

Avaliação antropométrica do estado nutricional da gestante: visão retrospectiva e prospectiva

Os autores analisam os fundamentos teóricos, critérios e modelos técnicos utilizados nos últimos 40 anos na avaliação antropométrica do estado nutricional durante a gravidez. Propõem que novos estudos objetivando uma solução metodológica para o problema da avaliação somatométrica da gestante devem ser desvinculados da condição "peso ao nascer" como referencial dominante na avaliação do método, considerando este requisito como um apriorismo sem consistência com os resultados observados.

Maternal body fat and water during pregnancy: do they raise infant birth weight?

OBJECTIVE

Our purpose was to determine the relation to infant birth weight of maternal fat and lean tissue during early and late pregnancy.

DESIGN

Total and net maternal pregnancy weight, fat, and water were determined from measurements of total body water, body density, and bone mineral mass in 200 women, with the use of a multicompartment model for body fat estimation in early and late pregnancy. Regression modeling was used to determine the relation of maternal body composition to birth weight, with control for maternal age, height, parity, and race and for infant gestational age and sex.

RESULTS

Maternal weight and body water at term were significantly associated with infant birth weight, but maternal body fat at term was not. These relations remained when maternal net values were used for weight, fat, and water to eliminate the contribution of the conceptus to these components.

CONCLUSION

In well-nourished women delivering at term, maternal body fat near term does not contribute significantly to infant birth weight, but maternal body water does.

The views of women of above average weight about appropriate weight gain in pregnancy

OBJECTIVE

To examine the beliefs of women of above average weight about appropriate levels of weight gain in pregnancy.

DESIGN

An in-depth qualitative study of 37 women.

SETTING

Women recruited from a city hospital, a rural hospital and by community midwives in the south of England.

PARTICIPANTS

Women were identified via hospital notes or by community midwives. Over a one-year period all women identified who attained the weight of 90 kg by the 30th week of pregnancy were eligible to participate. The sample comprised 37 women. The sample was varied in terms of age, social class, household composition and number of children.

MEASUREMENT

Two in-depth interviews were carried out with each interviewee: during late pregnancy and six weeks following childbirth.

FINDINGS

Interviewees were concerned not to weigh more after pregnancy than before. Their perceived ability to control weight gain during pregnancy was varied. In the perceived absence of specific advice from health professionals, they constructed their own views about appropriate levels of weight gain. These were informed by their desire to minimise weight gain and to provide adequate nourishment for the growth and development of their baby. Comments and advice from health professionals were interpreted within the women's own understandings of appropriate levels of weight gain.

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

(1) the desire to return to their pre-pregnancy weight was a strong motivating factor among pregnant women of above average weight, but some women lacked confidence in their ability to control weight gain; (2) the health and well-being of their unborn baby is often a central concern in women's decisions about appropriate weight gain; (3) health professionals need to explore the beliefs of women of above average weight about appropriate weight gain in pregnancy; and (4) written information about weight gain may assist women of above average weight in understanding what might be an appropriate level of weight gain during pregnancy.

The relationship between weight gain in pregnancy, birth-weight and postpartum weight retention

A total of 292 middle class, nonsmoking Chinese patients with known prepregnant weight who subsequently had uncomplicated singleton pregnancies delivering after 36 weeks' gestation were recruited to assess their serial antenatal weight gain, weight at 6 weeks and 3 months postpartum. The average prepregnant body mass index in the whole group was 20.4 kg/m2 (SD 2.19), and the total pregnancy weight gain was 14 kg (SD 3.75). Those with weight gain over 17.83 kg (one SD above the mean) (n=58) had higher weight gain in all 3 trimesters taken separately, as well as higher weight retention at 6 weeks and 3 months postpartum (p <0.001). Similar differences were noted for those with total weight gain over 2 standard deviations above the mean. The average weight retained at 3 months postpartum was 3.64 kg (SD 2.75). Those with weight retention over 9.14 kg (2 SD above the mean) (n=8) had a significantly higher second and third trimester weight gain (p <0.01) compared to the rest. These data suggest that excessive weight gain during pregnancy for women with prepregnant BMI in the normal range occurred most significantly after the mid-trimester, and was associated with higher postpartum weight retention without significant increase in birth-weight.

Weight-related distress in the early months after childbirth

The purpose of this study was to assess the extent of weight-related distress reported by new mothers and to explore associations of anthropometric and psychosocial variables with feelings about weight. New mothers' (N = 227) written descriptions of feelings about their weight were categorized using content analysis. More than 40% were somewhat satisfied with their weight, another 40% were mildly dissatisfied, and 8% experienced weight-related distress. Higher prepregnancy body mass index, larger gestational weight gain, higher current postpartum body mass index, less healthy lifestyle, and greater body image dissatisfaction were associated significantly with more dissatisfied/distressed feelings about weight. Results support the need for greater attention to the psychosocial significance of weight after childbirth.

Gestational weight gain as a predictor of birth and placenta weight according to pre-pregnancy body mass index

OBJECTIVE

To study the association between gestational weight gain and different birth weight indicators considering the pre-pregnancy body mass index. It was hypothesized that a high body mass index (BMI) would modify the effect of gestational weight gain and support the advice of keeping gestational weight gain at a moderate level in case of obesity.

STUDY DESIGN

A follow-up study of consecutively recruited women in two well defined geographical areas in Denmark. The recruitment lasted from 1984 to 1987 and 11,850 pregnant women and newborns were included in the study. The remaining analyses were restricted to non-diabetic women who gave birth between weeks 37 and 42 of gestation for whom weight gain was reported-altogether 7,122 women.

RESULTS

Birth and placenta weight were associated with gestational weight gain but with lower regression coefficients at higher BMI. The proportion of newborns with a birth weight of 4,500 grams or more increased with increasing gestational weight gain, especially in women with a BMI above 26.

CONCLUSION

The potential benefit of a high gestational weight gain in obese patients should be balanced by the higher risk of giving birth to babies with a birth weight of more than 4,500 grams and the risk of exaggerating a pre-existing state of obesity.

Unexpected relationship between fat mass and basal metabolic rate in pregnant women

We investigated the relationships between BMR, fat-free mass (FFM) and fat mass in pregnancy. BMR was measured by indirect calorimetry and body composition was assessed by densitometry in seventeen non-pregnant women (79.9 (SD 26.3, range 50.5-151.4) kg) and sixteen pregnant women (75.7 (SD 20.6, range 54.5-115.9) kg). The pregnant women were evaluated during weeks 31-35 of gestation. Multiple regression analysis of BMR with FFM and fat mass in the non-pregnant women showed that FFM was a highly significant predictor of BMR (P < 0.0001), but fat mass was not (P = 0.09). In contrast, in the pregnant women, multiple regression analysis revealed that fat mass was a highly significant predictor (P < 0.001), while FFM was not (P = 0.69). Evaluation of the interaction terms in the combined data set confirmed that the relationships of BMR with FFM and fat mass differ significantly in non-pregnant and pregnant women. It is proposed that pregnancy represents a unique condition during which BMR is regulated by maternal adipose reserves. An augmented BMR in overweight pregnant women may be protective, given that excessive weight gain may be detrimental to neonatal and maternal health.