The effect of lactation and other factors on post-partum changes in body-weight and triceps skinfold thickness

Breastfeeding Beyond 12 Months: Is There Evidence for Health Impacts?

Because breastfeeding provides optimal nutrition and other benefits for infants (e.g., lower risk of infectious disease) and benefits for mothers (e.g., less postpartum bleeding), health organizations recommend that healthy infants be exclusively breastfed for 4 to 6 months in the United States and 6 months internationally. Recommendations related to how long breastfeeding should continue, however, are inconsistent. The objective of this article is to review the literature related to evidence for benefits of breastfeeding beyond 1 year for mothers and infants. In summary, human milk represents a good source of nutrients and immune components beyond 1 year. Some studies point toward lower infant mortality in undernourished children breastfed for >1 year, and prolonged breastfeeding increases interbirth intervals. Data on other outcomes (e.g., growth, diarrhea, obesity, and maternal weight loss) are inconsistent, often lacking sufficient control for confounding variables. There is a substantial need for rigorous, prospective, mixed-methods, cross-cultural research on this topic. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Food insecurity, but not HIV-infection status, is associated with adverse changes in body composition during lactation in Ugandan women of mixed HIV status

BACKGROUND

Body composition is an important indicator of nutritional status and health. How body composition changes during 12 mo of breastfeeding in HIV-infected women receiving antiretroviral therapy (ART) is unknown.

OBJECTIVE

We assessed whether HIV or food insecurity was associated with adverse postpartum body-composition changes in Ugandan women.

DESIGN

A cohort of 246 women [36.5% of whom were HIV positive (HIV+) and were receiving ART] were followed to 12 mo postpartum. Repeated measures included weight, fat mass, fat-free mass, midupper arm circumference, triceps skinfold thickness [which allowed for the derivation of arm muscle area (AMA) and arm fat area (AFA)], breastfeeding, and individual food insecurity. Longitudinal regression models were constructed to assess associations between HIV and food insecurity and changes in body composition over time.

RESULTS

At baseline, HIV+ women compared with HIV-negative women had a higher mean ± SD food-insecurity score (11.3 ± 5.5 compared with 8.6 ± 5.5, respectively; P < 0.001) and lower AMA (40.6 ± 5.7 compared with 42.9 ± 6.9 cm³, respectively; P = 0.03). Participants were thin at 1 wk postpartum [body mass index (BMI; in kg/m²): 22.9 ± 2.9]. From 1 wk to 12 mo, the weight change was -1.4 ± 4.4 kg. In longitudinal models of body-composition outcomes, HIV was not associated with body composition (all P > 0.05), whereas food insecurity was inversely associated with body weight and BMI at 6, 9, and 12 mo and with AFA at 6 and 12 mo (all P < 0.05). At 6 mo, every 1-unit increase in the food-insecurity score was associated with a 0.13-kg lower body weight (P < 0.001) and a 0.26-cm³ lower AFA (P < 0.01).

CONCLUSIONS

Body-composition changes are minimal during lactation. HIV is not associated with body composition; however, food insecurity is associated with changes in body composition during lactation. This trial was registered at clinicaltrials.gov as NCT02922829 and NCT02925429.

The Associations of Maternal Weight Change with Breastfeeding, Diet and Physical Activity During the Postpartum Period

OBJECTIVE

To determine the association between breastfeeding practices, diet and physical activity and maternal postpartum weight.

METHODS

This was a secondary data analysis of a randomized community trial on beneficiaries of the Programa de Desarrollo Humano Oportunidades, recently renamed Prospera (n = 314 pregnant women), without any diseases that could affect body weight. Generalized estimating equations were used to determine the association between postpartum weight change and changes in diet, physical activity and type of breastfeeding.

RESULTS

The mean postpartum weight change from the first to the third month was 0.6 ± 2.2 kg. Women who breastfed exclusively for 3 months had a 4.1 (SE = 1.9) kg weight reduction in comparison with women who did not provide exclusive breastfeeding or who discontinued breastfeeding before 3 months (p = 0.04). There was no association between postpartum weight change and physical activity (p = 0.24) or energy intake (p = 0.06).

CONCLUSIONS

Exclusive breastfeeding was associated with maternal postpartum weight reduction. These results reinforce the World Health Organization recommendation of exclusive breastfeeding during the first 6 months of life in order to reduce the risk of weight retention or weight gain in postpartum women. It has been well established that exclusive breastfeeding is beneficial for both infants and mothers, but promoting breastfeeding as a strategy to promote postpartum weight loss is of paramount importance, especially in countries like Mexico where excessive weight in women of reproductive age is a public health problem.

Breast-feeding and postpartum weight retention: a systematic review and meta-analysis

OBJECTIVE

Weight gained during pregnancy and postpartum weight retention might contribute to obesity in women of childbearing age. Whether breast-feeding (BF) may decrease postpartum weight retention (PPWR) is still controversial. The purpose of our systematic review and meta-analysis was to investigate the relationship between BF and PPWR.

DESIGN

Three databases were systematically reviewed and the reference lists of relevant articles were checked. Meta-analysis was performed to quantify the pooled standardized mean differences (SMD) of BF on PPWR by using a random-effect model. Heterogeneity was tested using the χ 2 test and I 2 statistics. Publication bias was estimated from Egger's test (linear regression method) or Begg's test (rank correlation method).

RESULTS

Among 349 search hits, eleven studies met the inclusion criteria for the meta-analysis. Seven studies were conducted in the USA, one in Brazil, one in France, one in Georgia and one in Croatia. Compared with formula-feeding, BF for 3 to ≤6 months seemed to have a negative influence on PPWR and if BF continued for >6 months had little or no influence on PPWR. In a subgroup meta-analysis, the results did not change substantially after the analysis had been classified by available confounding factors. There was no indication of a publication bias from the result of either Egger's test or Begg's test.

CONCLUSIONS

Although the available evidence held belief that BF decreases PPWR, more robust studies are needed to reliably assess the impact of patterns and duration of BF on PPWR.

Effect of lactation on maternal postpartum cardiac function and adiposity: a murine model

OBJECTIVE

Lactation is associated with reduction in maternal metabolic disease and hypertension later in life; however, findings in humans may be confounded by socioeconomic factors. We sought to determine the independent contribution of lactation on cardiovascular parameters and adiposity in a murine model.

STUDY DESIGN

Following delivery, CD-1 female mice were randomly divided into 2 groups: lactated (L; nursed pups for 3 weeks, n = 10), and nonlactated (NL; pups were removed after birth, n = 12). Blood pressure (BP) was assessed prepregnancy and at 1 and 2 months' postpartum. Visceral and subcutaneous adipose tissue determined by computed tomography and left ventricular ejection fraction, cardiac output, and the E/A ratio determined by microultrasound were evaluated at 1 and 2 months' postpartum. The results were analyzed using a Student t test (significance at P < .05).

RESULTS

We observed a significantly different maternal BP at 2 months' postpartum with relatively greater BP in NL (systolic BP: NL, 122.2 ± 7.2 vs L, 96.8 ± 9.8 mm Hg; P = .04; diastolic BP: NL, 87.0 ± 6.8 vs L, 65.9 ± 6.2 mm Hg; P = .04). Visceral adipose tissue was significantly increased in NL mice at 1 (22.0 ± 4.1% vs 10.7 ± 1.8%, P = .04) and 2 months' postpartum (22.9 ± 3.5% vs 11.2 ± 2.2%, P = .02), whereas subcutaneous adipose tissue did not differ between the groups. At 2 months' postpartum, ejection fraction (51.8 ± 1.5% vs 60.5 ± 3.8%; P = .04), cardiac output (14.2 ± 1.0 vs 18.0 ± 1.3 mL/min; P = .02) and mitral valve E/A ratio (1.38 ± 0.06 vs 1.82 ± 0.13; P = .04) were significantly lower in NL mice than L mice.

CONCLUSION

Our data provide evidence that interruption of lactation adversely affects postpartum maternal cardiovascular function and adiposity.

Predictors of post-partum weight retention in a prospective longitudinal study

Post-partum weight retention (WR) occurs in 60-80% of women with some retaining ≥10 kg with contributing factors reported as pre-pregnancy body mass index (BMI), gestational weight gain (GWG) and breastfeeding. A longitudinal study of pregnancy, with 12-month post-partum follow-up was conducted to determine factors associated with WR. Pregnant women (n = 152) were recruited from the John Hunter Hospital antenatal clinic in New South Wales, Australia. Pre-pregnancy weight was self-reported; weight was measured four times during pregnancy (for GWG) and in the first 12 months post-partum. Infant feeding data were obtained via questionnaires. Breastfeeding was categorised as exclusive, predominant, complementary or not breastfeeding. Linear mixed models tested the predictors of WR, with and without adjustment for potential confounders. Compared with pre-pregnancy weight, 68% of women retained weight at 12 months, median (interquartile range) [4.5 kg (2.1-8.9)]. After adjustment, GWG was positively associated with WR (P < 0.01), but pre-pregnancy weight did not predict WR. For each additional week of any breastfeeding, 0.04 kg less weight was retained. Compared with women who retained weight, those women who did retain had higher rates of exclusive breastfeeding at three months (P < 0.05), but the number of weeks of exclusive breastfeeding failed to predict WR for all women. WR following childbirth is common and associated with GWG, while the number of weeks of 'any' breastfeeding contributed to post-partum weight loss. Whether these factors are modifiable strategies to optimise the weight status of women at this life stage requires further research.

Duration of lactation, maternal metabolic profile, and body composition in the Norwegian EBBA I-study

OBJECTIVE

There is conflicting evidence as to whether duration of lactation may decrease the risk of subsequent development of an unfavorable maternal metabolic profile, including overweight and obesity. We hypothesized that duration of lactation is associated with a more favorable metabolic profile and healthier anthropometric measurements.

SUBJECTS AND METHODS

Ninety-eight parous women were studied from the Norwegian EBBAI-study (Energy Balance and Breast cancer Aspects-study), a cross-sectional study of healthy premenopausal women 25-35 years old. Historical lactation data were collected, anthropometric measurements were taken, fasting blood samples (for serum glucose, triglycerides, total cholesterol, and high-density lipoprotein cholesterol) were drawn, and women were asked to fill in a precoded food diary.

RESULTS

Mean time since last birth was 4.7 years, mean number of children was 1.9, mean total duration of lactation was 19 months, and average length of lactation per child was 10.3 months. Women who on average lactated for less than 10 months per child had higher mean levels of fasting serum glucose (5.2 mmol/L vs. 5.0 mmol/L, p=0.04), serum triglyceride (0.91 mmol/L vs. 0.66 mmol/L, p=0.001), and serum cholesterol (4.78 mmol/L vs. 4.32 mmol/L, p=0.004) and a higher waist-to-hip ratio (0.81 vs. 0.77, p=0.001) than women who lactated for 10 months or more per child. The inverse association between average length of lactation per child and waist-to-hip ratio persisted after adjustment for potential confounders.

CONCLUSIONS

These results support the hypothesis that duration of lactation may be associated with a healthier metabolic profile and healthier anthropometric measurements, especially lipid levels and waist-to-hip ratio, even years after weaning.

Associations of Body Mass and Body Fat Distribution with Parity Among African-American and Caucasian Women: The CARDIA Study

Associations of parity with body fat and its distribution are poorly understood; therefore, we examined the relationships between parity and obesity in young adult women. Body mass index (BMI), skin-folds, and waist-hip ratio were compared in 1452 African-American and 1268 Caucasian nonpregnant women aged 18 to 30, adjusting for age (where no age-parity interactions were present), education, physical activity (assessed by questionnaire) and fitness (assessed by graded exercise test), dietary fat intake, alcohol and smoking. Adjusted mean BMI was significantly higher in African-American women aged 25-30 years with three or more children (28.5 kg/m2) than in those with two (27.0 kg/m2), one (26.2 kg/m2), or no children (26.3 kg/m2). Similar trends were found in Caucasians (BMI = 23.3, 23.4, 23.7, 25.0 kg/m2 for parity = 0, 1, 2, > or = 3, respectively), but the mean BMI was significantly higher in African Americans in each parity group. The association between BMI and parity was not present among women 18-24 years of age. Skinfolds were directly associated with parity in African Americans only. Waist-hip ratios were generally lower among nulliparous than parous women in both ethnic groups; race differences were present only among nulliparas. In conclusion, parity was associated with BMI in women aged 25 to 30 years but did not explain ethnicity-related differences in body mass.

Lactation and cardiovascular risk factors in mothers in a population-based study: the HUNT-study

Background

Lactation has beneficial short term effects on maternal metabolic health, but the long term effects are less well known.

Methods

We studied the association between lifetime duration of lactation and cardiovascular risk factors in mothers later in life among 21,368 parous women aged 20 to 85 years attending the second Nord-Trøndelag Health Study (HUNT2) in 1995–1997, Norway, a cross-sectional population-based study. General linear modelling was used to calculate mean values of known cardiovascular risk factor levels in five categories of lifetime duration of lactation. Logistic regression was conducted to estimate odds ratios of hypertension, obesity and diabetes.

Results

Among women aged 50 years or younger, lifetime duration of lactation was significantly and inversely associated with body mass index (P-trend, < 0.001), waist circumference (P-trend, < 0.001), systolic and diastolic blood pressure (both P-trends, < 0.001), and serum levels of triglycerides, total cholesterol and low density lipoprotein cholesterol (all P-trends, < 0.001) after adjustment for covariates. Parous women aged 50 years or younger who had never lactated had higher prevalence of hypertension, obesity and diabetes. In this age group, compared to women who had lactated for 24 months or more, parous women who had never lactated had an OR for hypertension of 1.88 (95% CI 1.41, 2.51), an OR for obesity of 3.37 (95% CI 2.51, 4.51) and an OR for diabetes of 5.87 (95% CI 2.25, 15.3). Among women older than 50 years there were no clear associations.

Conclusion

Lifetime duration of lactation was associated with long term reduced cardiovascular risk levels in mothers aged 50 years or younger.

Maternal visceral adiposity by consistency of lactation

The purpose of this study was to examine the assocation between lactation and maternal visceral adiposity among US women who were on average 7 years postpartum. This cross-sectional analysis included 89 women who gave birth between 1997 and 2002, who did not have preeclampsia, prepregnancy hypertension or prepregnancy diabetes, and enrolled in The Women and Infant Study of Healthy Hearts (WISH). Computed tomography was used to assess abdominal adiposity. History of lactation was self-reported. Visceral adiposity was greater by 36.96 cm(2) (95% CI: 20.92,53.01) among mothers who never breastfed than mothers who breastfed for ≥3 months after every birth, even after adjustment for age, parity, years since last birth, site, socioeconomic, lifestyle, psychological, and family history variables, early adult BMI, and current BMI. Similarly, in fully adjusted models, mothers who breastfed any of their children for less than 3 months had 20.38 cm(2) (95% CI: 2.70, 38.06) greater visceral adiposity than mothers who consistently breastfed all their children for 3 or more months. This study found that 7 years postpartum visceral fat depots are significantly greater among mothers who lactated for less than 3 months after the birth of each of their children. These results provide a potential physiologic basis for prior findings that women who do not consistently breastfeed are at an increased risk of diabetes, cardiovascular disease, and the metabolic syndrome.

Breastfeeding and subsequent maternal visceral adiposity

Women gain visceral fat during pregnancy. Studies examining the impact of breastfeeding on maternal body composition are inconclusive. We examined the extent to which breastfeeding was associated with visceral adiposity in a sample of US women. This was a cross-sectional analysis of 351 women aged 45-58 years, who were free of clinical cardiovascular disease and had not used oral contraceptives or hormone replacement therapy in the 3 months prior to enrollment in the Study of Women's Health Across the Nation (SWAN)-Heart Study (2001-2003). History of breastfeeding was self-reported. Computed tomography was used to assess abdominal adiposity. Among premenopausal/early-peri-menopausal mothers, those who never breastfed had 28% greater visceral adiposity (95% confidence interval (CI): 11-49, P = 0.001), 4.7% greater waist-hip ratio (95% CI: 1.9-7.4, P < 0.001), and 6.49 cm greater waist circumference (95% CI: 3.71-9.26, P < 0.001) than mothers who breastfed all of their children for ≥3 months in models adjusting for study site; age; parity; years since last birth; socioeconomic, lifestyle, and family history variables; early adult BMI; and current BMI. In comparison to women who were nulliparous, mothers who breastfed all of their children for ≥3 months had similar amounts of visceral fat (P > 0.05). In contrast, premenopausal/early-peri-menopausal mothers who had never breastfed had significantly greater visceral adiposity (42% (95% CI: 17-70), P < 0.001), waist circumference (6.15 cm (95% CI: 2.75-9.56), P < 0.001), and waist-hip ratio (3.7% (95% CI: 0.69-6.8), P = 0.02) than nulliparous women. No significant relationships were observed among late peri-menopausal/postmenopausal women. In conclusion, until menopause, mothers who did not breastfeed all of their children for ≥3 months exhibit significantly greater amounts of metabolically active visceral fat than mothers who had breastfed all of their children for ≥3 months.

Prolonged breast-feeding protects mothers from later-life obesity and related cardio-metabolic disorders

Objective

To investigate the long-term effects of duration of postpartum lactation on maternal body composition and risk for cardio-metabolic disorders in later life.

Design

Retrospective study. Body composition was measured using dual-energy X-ray absorptiometry and serum glucose, insulin and lipids were analysed using enzymatic photometric methods 16–20 years after the last pregnancy. Medical history and lifestyle factors were collected via a self-administered questionnaire. Detailed information regarding weight change patterns during each pregnancy was obtained from personal maternity tracking records.

Setting

City of Jyväskylä and surroundings in Central Finland.

Subjects

Two hundred and twelve women (mean age 48, range 36–60 years).

Results

At 16–20 years after their last pregnancy, women who had breast-fed for less than 6 months had higher total body fat mass and fat mass percentage, particularly in the android region (46·5 (sd8·2) %) than mothers who had breast-fed for longer than 6 months (39·0 (sd10·2) %) or for longer than 10 months (38·4 (sd10·9) %,P< 0·01). These differences were independent of pre-pregnancy weight and BMI, menopausal status, smoking status, level of education, participation in past and present leisure-time physical activity, and current dietary energy intake. Higher body fat mass was also associated with higher fasting serum glucose concentration and insulin resistance, TAG, LDL cholesterol and total cholesterol concentrations, as well as higher systolic and diastolic blood pressure (P< 0·05 for all).

Conclusions

Short duration of breast-feeding may induce weight retention and fat mass accumulation, resulting in increased risk of cardio-metabolic disorders in later life.

Sociodemographic, perinatal, behavioral, and psychosocial predictors of weight retention at 3 and 12 months postpartum

Postpartum weight retention plays an important role in the pathway leading to obesity among women of childbearing age. The objective of this study was to examine predictors of moderate (1-10 pounds) and high (>10 pounds) postpartum weight retention using data from a prospective pregnancy cohort that followed women into the postpartum period; n = 688 and 550 women at 3 and 12 months, respectively. Analysis included descriptive statistics and predictive modeling using log-binomial techniques. The average weight retained at 3 and 12 months postpartum in this population was 9.4 lb (s.d. = 11.4) and 5.7 lb (s.d. = 13.2), respectively. At 3 months postpartum, prepregnancy weight, gestational weight gain, and hours slept during the night were associated with moderate or high weight retention, whereas having an infant hospitalized after going home and scoring in the upper 75th percentile of the Eating Attitudes Test (EAT) were associated only with high weight retention. At 12 months postpartum, prepregnancy weight, gestational weight gain, and maternal education were associated with moderate weight retention; and gestational weight gain, maternal age, race, employment status, and having an infant hospitalized at birth were associated with high weight retention. The results of this study illustrate the importance of prepregnancy weight and gestational weight gain in predicting postpartum weight retention. Furthermore, given the lack of successful intervention studies that exist to date to help women lose weight in the postpartum period, the results of this study may help to inform future interventions that focus on such aspects as hours of sleep, dealing with stress associated with a hospitalized infant, and nonclinical eating disorder symptomatology.

Effect of breast-feeding on weight retention at 3 and 6 months postpartum: data from the North Carolina WIC Programme

OBJECTIVE

Pregnancy-related weight retention can contribute to obesity, and breast-feeding may facilitate postpartum weight loss. We investigated the effect of breast-feeding on postpartum weight retention.

DESIGN

A retrospective follow-up study of weight retention, compared in women who were fully breast-feeding, combining breast-feeding with formula-feeding (mixed feeding), or formula-feeding at 3 months (n 14 330) or 6 months (n 4922) postpartum, controlling for demographic and weight-related covariates using multiple linear regression.

SETTING

The North Carolina Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).

SUBJECTS

Participants in the North Carolina WIC Programme who delivered a baby between 1996 and 2004.

RESULTS

In covariate-adjusted analyses, there was no association between breast-feeding and weight retention at 3 months postpartum. At 6 months postpartum, as compared to formula-feeders, mean weight retention was 0·84 kg lower in mixed feeders (95 % CI 0·39, 1·29; P = 0·0002) and 1·38 kg lower in full breast-feeders (95 % CI 0·89, 1·87; P ≤ 0·0001).

CONCLUSIONS

Breast-feeding was inversely associated with weight retention at 6 months postpartum in this large, racially diverse sample of low-income women. Further, full breast-feeding had a larger protective effect than did breast-feeding combined with formula-feeding.

Health effects of breast feeding for mothers: a critical review

Lactation results in a number of physiological adaptations which exert direct effects on maternal health, some of which may confer both short and long term advantages for breast feeding mothers. Breast feeding in the early postpartum period promotes a more rapid return of the uterus to its prepregnant state through the actions of oxytocin. Breast feeding may also lead to a more rapid return to prepregnancy weight. Among studies that had good data on duration and intensity of lactation, the majority show a significant association between lactation and weight loss. However, there is no evidence that lactation prevents obesity. Lactation also affects glucose and lipid metabolism. The long term effects of these adaptations are unknown but may have implications for preventing subsequent development of diabetes and heart disease. Lactation delays the return of ovulation and significantly reduces fertility during the period of lactational amenorrhoea. This process is linked with feeding patterns and may therefore be affected by practices such as scheduled feedings and the timing of introduction of complementary foods. While the evidence from epidemiologic studies is mixed, several large studies have shown that extended lactation is associated with reduced risk of premenopausal breast, ovarian and endometrial cancers. Although bone mineralization declines during lactation, repletion takes place after weaning. As a result, breast feeding does not appear to cause long term depletion of bone nor does it increase risk of osteoporosis. Many of the physiological effects of lactation are dependent on the stimulation of the hypothalamic-pituitary axis and milk removal and thus may vary with infant feeding practices. Well controlled studies are needed that include detailed information regarding infant feeding practices in addition to the total duration of any breast feeding. Future feeding recommendations should reflect careful consideration of how such practices affect both infant and maternal health.

Effect of infant feeding on maternal body composition

BACKGROUND

Women gain total body weight and accrue body fat during pregnancy. Breastfeeding has been suggested as an efficient means of promoting postpartum weight loss due to its high energy cost. We investigated the effect of infant feeding mode on maternal body composition.

METHODS

This study evaluated maternal weight and percent body fat changes in exclusively breastfeeding versus mixed feeding mothers during the first 12 weeks postpartum using the BOD POD. Twenty four mothers aged 19 - 42 years were studied. Participants were recruited from Athens-Clarke County and surrounding areas of the State of Georgia, USA. The study was conducted between November 2005 and December 2006.

RESULTS

Prepregnancy weight was higher in mixed feeding mothers than in exclusively breastfeeding mothers (68.4 kg vs. 61.4 kg) but the difference was not statistically significant. At 12 weeks postpartum, exclusively breastfeeding mothers had lost more total body weight than mixed feeding mothers (4.41 +/- 4.10 kg versus 2.79 +/- 3.09 kg; p = 0.072). There was no significant difference in fat weight change between the two groups (4.38 +/- 2.06 kg versus 4.17 +/- 2.63 kg). However, mixed feeding mothers lost slightly more percent body fat than exclusively breastfeeding mothers (1.90 +/- 4.18 kg versus 1.71 +/- 3.48 kg), but the difference was not statistically significant. The trend in percent body fat loss was significant among exclusively breastfeeding mothers (p = 0.034) but not mixed feeding mothers (p = 0.081). Exclusively breastfeeding mothers consumed more calories than mixed feeding mothers (1980 +/- 618 kcal versus 1541 +/- 196 kcal p = 0.08). Physical activity levels were, however, higher in mixed feeding mothers than exclusively breastfeeding mothers.

CONCLUSION

Our results provide further evidence that exclusive breastfeeding promotes greater weight loss than mixed feeding among mothers even in the early postpartum period. This suggests that there is the need to encourage mothers to exclusively breastfeed as a means of overweight and obesity prevention.

Duration of breast-feeding and the incidence of type 2 diabetes mellitus in the Shanghai Women's Health Study

AIMS/HYPOTHESIS

The aim of this study was to examine the association between lifetime breast-feeding and the incidence of type 2 diabetes mellitus in a large population-based cohort study of middle-aged women.

METHODS

This was a prospective study of 62,095 middle-aged parous women in Shanghai, China, who had no prior history of type 2 diabetes mellitus, cancer or cardiovascular disease at study recruitment. Breast-feeding history, dietary intake, physical activity and anthropometric measurements were assessed by in-person interviews. The Cox regression model was employed to evaluate the association between breast-feeding and the risk of type 2 diabetes mellitus.

RESULTS

After 4.6 years of follow-up, 1,561 women were diagnosed with type 2 diabetes mellitus. Women who had breastfed their children tended to have a lower risk of diabetes mellitus than those who had never breastfed [relative risk (RR)=0.88; 95% CI, 0.76-1.02; p=0.08]. Increasing duration of breast-feeding was associated with a reduced risk of type 2 diabetes mellitus. The fully adjusted RRs for lifetime breast-feeding duration were 1.00, 0.88, 0.89, 0.88, 0.75 and 0.68 (p trend=0.01) for 0, >0 to 0.99, >0.99 to 1.99, >1.99 to 2.99, >2.99 to 3.99 and >or=4 years in analyses adjusted for age, daily energy intake, BMI, WHR, smoking, alcohol intake, physical activity, occupation, income level, education level, number of live births and presence of hypertension at baseline.

CONCLUSIONS/INTERPRETATION

Breast-feeding may protect parous women from developing type 2 diabetes mellitus later in life.

Diet, energy expenditure, and body composition of lactating Ribeirinha women in the Brazilian Amazon

Lactation is the most energetically demanding part of human reproduction; yet, compared with pregnancy, we know little about the strategies women in different settings employ to cope with these increased energy demands. This paper takes a biocultural approach and reports longitudinal data on the anthropometry, dietary intakes and energy expenditure of a sample of 23 rural, lactating Ribeirinha women living in subsistence-based communities in the eastern Amazon. The dietary intakes of these lactating women were insufficient to meet their lactating energy needs and were least sufficient during resguardo, a 40-day period in the immediate postpartum when the women observed a series of food taboos and work restrictions. Instead, the women in this study met the increased energy demands of lactation by drawing on their energy reserves and reducing their energy expenditure in physical activity. The women showed a significant reduction in weight (P<0.001), BMI (P<0.001) and in circumferences (hip, P=0.01; waist, P=0.03) and skinfolds (thigh, P=0.03) in the gluteal femoral region. Total daily energy expenditure (TDEE) was lowest during resguardo and increased as lactation progressed (P=0.01). While the practice of resguardo reduced maternal energy expenditure and allowed women more time to spend with their newborn infants, it came at a cost (low dietary intake), which appears to be related to the loss of the adult woman from subsistence activities. By taking a biocultural approach this study illustrates the role the social environment plays in shaping the experience of lactating women.

Fatores associados com a retenção e o ganho de peso pós-parto: uma revisão sistemática

INTRODUÇÃO: A retenção de peso após o parto é um dos determinantes da obesidade em mulheres. Seu desenvolvimento está relacionado com o ganho de peso gestacional, paridade, idade, situação marital, consumo energético, atividade física e lactação, mas as associações encontradas têm se mostrado inconclusivas e contraditórias. Objetivos: Avaliar estudos que identificaram fatores preditores da retenção e ganho de peso após o parto. MATERIAL E MÉTODOS: Foi realizada uma revisão de literatura na Base de Dados LILACS e MEDLINE, referente aos anos de 1993 a 2003. RESULTADOS: Vinte e oito artigos foram identificados, sendo 23 estudos de coorte, quatro estudos transversais e um estudo caso-controle. A maioria dos estudos foi realizada nos EUA e o tempo de acompanhamento após o parto ocorreu principalmente entre seis semanas e 24 meses. Cerca de 25% dos estudos apresentaram perdas superiores a 30%, 61% incluíram adolescentes na amostra e 75% não aferiram o peso pré-gestacional. Sete estudos foram considerados de melhor qualidade, pois utilizaram o peso pré-gestacional medido, incluíram grupo de comparação, excluíram adolescentes, apresentaram perdas de seguimento inferiores a 30% e controlaram para variáveis de confundimento. CONCLUSÃO: Ganho de peso gestacional, raça negra e paridade estão associados positivamente com a retenção de peso pós-parto. As evidências são contraditórias para a variável lactação e insuficientes para as variáveis consumo alimentar e atividade física. São necessários estudos cuidadosamente desenhados para esclarecer estas questões.

Breastfeeding and postpartum weight retention in a cohort of Brazilian women

BACKGROUND

The relation between postpartum weight retention and breastfeeding practices is controversial.

OBJECTIVE

Defining breastfeeding as the period when a child is exclusively or predominantly breastfed, we studied the association between breastfeeding duration and postpartum weight retention.

DESIGN

We followed 405 women aged 18-45 y who were assessed at 0.5, 2, 6, and 9 mo postpartum. The outcome variable, postpartum weight retention, was expressed as the difference between the observed weight at each follow-up and the reported prepregnancy weight. The main statistical procedure used was the longitudinal mixed-effects model.

RESULTS

Mean postpartum weight retention at the end of the study was 3.1 kg. Single women aged > or = 30 y retained more weight than did younger single women or married women. The combined effect of breastfeeding duration and percentage of body fat at baseline was significant only for women with < 30% body fat. According to the model's prediction, when women who had 22% body fat and breastfed for 180 d were compared with those who had 22% body fat and breastfed for only 30 d, each month of breastfeeding contributed -0.44 kg to postpartum weight retention. When only the percentage of body fat was varied, the total effect was 3.0, 1.7, 1.2, and 0.04 kg in women with 18%, 25%, 28%, and 35% body fat, respectively.

CONCLUSIONS

These results support the hypothesis of an association between breastfeeding and postpartum weight retention and suggest that encouraging prolonged breastfeeding might contribute to decreases in postpartum weight retention.

Weight development over time in parous women--the SPAWN study--15 years follow-up

BACKGROUND

Weight gain is common after pregnancy. Most studies suggest that weight gain associated with a pregnancy is between 0.5 and 3.8 kg up to 2.5 y of follow-up. However, 73% of the female patients at our obesity clinic identified pregnancy as an important trigger for marked weight retention. The majority retained more than 10 kg after each pregnancy. The aim of this study was to examine long-term weight development after pregnancy in a 15 y follow-up of women who took part in the Stockholm Pregnancy And Women's Nutrition (SPAWN) study.

METHOD AND SUBJECTS

The SPAWN study is a long-term follow-up study of women who delivered children in 1984-85 in Stockholm (n=2342). A total of 1423 participants (response rate=61%) completed questionnaires, which covered eating behaviour and exercise, demographic information including social situation and status and details of the pregnancy before, during and up to 1 y after pregnancy. After 15 y, these women were invited to take part in the follow-up study. Anthropometric measurements and the same questionnaire data were collected from the 563 women who participated (response rate=40%). The sample was divided into two main groups: those who were normal weight before pregnancy and remained normal weight, and those who were normal weight before pregnancy and had become overweight at 15 y follow-up.

RESULTS

Those women who became overweight had a higher pre-pregnant body mass index (BMI) (22.3+/-1.5 vs 20.5+/-1.6 kg/m(2), P<0.001), gained more weight during pregnancy (16.3+/-4.3 vs 13.6+/-3.7 kg, P<0.001) and had retained more at 1 y follow-up. The women who became overweight had a steeper weight trajectory gaining more from 1 y follow-up to 15 y follow-up (11.1+/-6.5 vs 4.5+/-6.5 kg, P<0.001), with a higher BMI at 15 y follow-up of 27.5+/-2.6 vs 22.5+/-2.3 5 kg/m(2) (P<0.001). However, differences between those who became overweight and those who did not could not be explained by age, number of children and various socioeconomic factors. Features of pregnancy that did differ between the two groups were breastfeeding and smoking cessation. However, women who became overweight had lower lactation scores than women who remained normal weight. Relatively more subjects of the group that became overweight stopped smoking during pregnancy.

DISCUSSION

Pregnancy is a vulnerability factor for some women to become overweight. This study attempted to identify those factors that place initially normal weight women on a steeper weight trajectory as a result of pregnancy. Demographic, behavioural, physical and psychological characteristics only partly explain the weight gain observed at 15 y follow-up. Further research is required to investigate the relative role of these characteristics in predicting postpregnancy weight development.

Impact of Breastfeeding on Maternal Nutritional Status

This review covers the impact of breastfeeding on maternal postpartum weight loss and micronutrient status. Results regarding the impact on weight loss have been conflicting. This may be due to differences in study quality. Of six observational studies in which postpartum weight change was estimated (rather than measured directly), only one showed an association with breastfeeding. By contrast, six of the seven studies in which postpartum weight change was measured showed greater weight or fat loss in women who breastfed longer, particularly at 3 to 6 months postpartum. The results of the higher quality studies are consistent with two experimental studies conducted in Honduras, which demonstrated that the degree of breastfeeding affects the rate of weight loss. Thus, it appears that breastfeeding does enhance the rate of weight loss postpartum, but the effect is relatively small and may not be detectable in studies that lack adequate statistical power, have imprecise data on postpartum weight change, or do not account for the exclusivity and/or duration of breastfeeding. There is very little information with regard to micronutrient status during lactation. Nutrient requirements for vitamins A, B6, and C, and for iodine and zinc are increased by more than 50%, but lactation may actually be protective against maternal iron deficiency. More research is needed on the effects of lactation on maternal nutritional status and on strategies for optimizing nutrient intake to meet the needs of both the mother and her infant.

Impact of breastfeeding on anthropometric changes in peri-urban Toba women (Argentina)

We present an analysis of the effect of lactation on average maternal anthropometric and body composition measures in a population of Toba women in Formosa, Argentina. This indigenous population is undergoing a continuing transition from a seminomadic hunter-gatherer lifestyle to a sedentary, peri-urban one. Using a mixed-longitudinal design, we measured monthly maternal body mass index (BMI), body fat percentage, and triceps and subscapular skinfold thickness between birth and the 18th month postpartum in 113 breastfeeding women. The pattern of change in postpartum body composition varied with maternal age. Adult women (20 years old and older) did not show significant changes in any of the anthropometric measures during the entire study. Older adult women (30 years old and older) consistently had the highest values in measures of BMI and percentage fat, and tended to retain weight postpartum. Adolescent subjects (19 years old and younger) tended to lose weight during the first 6 months postpartum but regain their prepregnancy weight by 12 months postpartum. The same patterns were observed for changes in body fat percentage and in skinfold thickness. We conclude that in this population the energetic stress of lactation does not pose a serious challenge to the maintenance of long-term maternal energy balance or to short-term energy balance in women over 20 years of age. From a public health perspective, postpartum weight retention in older women may represent a more serious health threat. The low level of energetic stress associated with lactation may also contribute to the relatively short duration of lactational amenorrhea in this population despite a cultural pattern of intensive breastfeeding. Am. J. Hum. Biol. 15:717-724, 2003.

Effect of lactation on maternal body weight: a systematic review

The impact of lactation on maternal weight after delivery remains unclear. To address this question, we performed a systematic review of the literature. We searched PubMed, POPLINE, EMBASE, and LILACS computerized databases for relevant articles and classified the evidence using the U.S. Preventive Services Task Force rating system. We found 42 studies, of which 28 contained relevant information: 15 prospective cohort studies, 1 retrospective cohort study, 1 cross-sectional study, and 11 case-series reports. The methods used in these studies varied widely, thus precluding aggregation of results. Level II-2 and III evidence supports a class "C" recommendation: insufficient evidence exists to support an effect of lactation on maternal weight after delivery. Better longitudinal studies with a clear definition of breast-feeding; clear, specific outcome measures; study periods extending 1 or 2 years after delivery; and better control of potentially confounding factors will be needed to resolve this question.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to compile the literature on the effect of lactation on maternal weight, to compare the various studies, and to summarize the data on the effect of lactation on maternal weight gain.

Obesity and weight change related to parity and breast-feeding among parous women in Brazil

OBJECTIVE

Studies on the independent role of parity in long-term body weight change in economically developing countries are scarce and inconclusive, and only a few studies have taken into account patterns of breast-feeding. This association was examined in a national cross-sectional survey representative of Brazilian parous women.

DESIGN AND SETTING

The survey conducted in 1996 measured women's height and weight in the household and data on weight prior to the first pregnancy, parity and breast-feeding were recalled.

SUBJECTS

A sample of 2338 parous women, 15 to 49 years of age, 29 months after last delivery on average, had current body mass index (BMI, in kg m(-2)) modelled through hierarchical multiple linear regression analysis. Explanatory variables included parity, days of predominant breast-feeding, BMI pre-pregnancy, socio-economic, geographic, demographic and other reproductive variables.

RESULTS

Prevalences of overweight (BMI = 25.0-29.9 kg m(-2)) and obesity (BMI > or = 30.0 kg m(-2)) were 25.2% and 9.3%. The overall mean weight gain per year after the first pregnancy was 0.90 kg for an average time since first pregnancy of eight years. BMI pre-pregnancy modified the association between current BMI and parity. Therefore, weight change attributed to parity calculated for a woman of average height (1.56 m) was 0.60 kg greater for primiparous women with a BMI pre-pregnancy of 30 kg m(-2), compared with women with BMI pre-pregnancy of 25 kg m(-2). This greater weight retention among obese women was 1.21 kg for women with two children and 1.82 kg for women with three or more children. Parity reduced the effect of weight loss associated with lactation (1.75 kg for six months of lactation among primiparous women and 0.87 kg among women with three or more children). For the sub-sample of 793 primiparous women, a weight decrease of 300 g was associated with each month of predominant breast-feeding for all prior BMI levels.

CONCLUSIONS

In this study, weight change associated to reproduction was highly dependent on BMI previous to pregnancy and the effects of parity and lactation were small.

Breast-feeding has a limited long-term effect on anthropometry and body composition of Brazilian mothers

The effect of lactation on maternal nutrition is controversial. Some studies have shown that breast-feeding reduces maternal weight, whereas some have not. All studies have been restricted to the first 2 y after delivery. We investigated the effect of lactation on maternal nutrition 5 y after delivery. All mothers giving birth in the city of Pelotas, Brazil, in 1993 were interviewed and weighed soon after delivery; information was also obtained on prepregnancy weight. In 1994, information on breast-feeding duration and pattern was collected for a 20% subsample. They were seen again in 1998, and those eligible (nonsmokers, no subsequent pregnancy, last birth weight > or = 2500 g) underwent measurements for weight, height, waist, hip and arm circumferences, triceps and subscapular skinfolds. The following indices were calculated in 312 women: body mass index, waist/hip ratio, arm fat area, the percentage of body fat assessed through skinfolds, and weight and body mass index change since before conception. The percentage of body fat was also measured through bioimpedance for half of the sample. After adjustment for confounding, all outcomes generally showed a similar pattern, i.e., mothers who breast-fed for 6-11.9 mo had lower measurements than those with shorter or longer durations. However, only the association with bioimpedance was significant (P < 0.03), and that for arm fat area tended to be significant (P = 0.06). Exclusive or predominant breastfeeding at 4 mo was associated with lower waist circumference (P = 0.05) and the percentage of body fat measured through skinfolds (P = 0.04). This study suggests that the relationship between breast-feeding and long-term changes in maternal weight is complex and, in this population, not particularly strong.

Association of the maternal experience and changes in adiposity measured by BMI, waist:hip ratio and percentage body fat in urban Brazilian women

The aim of the present study was to determine the association between the maternal experience and changes in adiposity measured by BMI, percentage body fat (PBF) and waist:hip ratio (WHR). In a cross-sectional study, 203 women were recruited at health care and educational facilities in Brasilia, Brazil. These women were divided into three groups: fifty-three nulliparous (no full-term pregnancy); sixty-three primiparous (one full-term pregnancy); eighty-seven multiparous (two or more full-term pregnancies). Socio-economic, behavioural, reproductive and dietary data were collected. All the women were measured for weight, height, skinfold thicknesses and waist and hip circumferences. Analysis of covariance was used to measure the differences among the three groups in relation to BMI, PBF, and WHR, controlling for the following covariates: age; socio-economic status; use of oral contraceptives; smoking; energy intake level; cooking oil intake; physical activity level; lactation score; parity. The three groups of women differed significantly for BMI (P = 0.04), PBF (P = 0.0008), and WHR (P = 0.0001). Multiparous women presented higher BMI (P = 0.01) and PBF (P = 0.03) compared with primi- and nulliparous groups. PBF was also associated with age and high socio-economic status. Primi- and multiparous women showed a higher WHR than nulliparous women (P < 0.0001). Age and smoking habit were also factors associated with higher WHR.

Postpartum body composition changes in lactating and non-lactating primiparas

The objective of this study is to evaluate the postpartum body composition changes in lactating versus non-lactating or formula-feeding primiparas during the first 12 wk. Twenty primiparous females (age range 17-35 y) who decided to nurse or formula feed their infant were studied. The non-lactating mothers (n = 6) were younger (21 versus 29 y) and had a lower prepregnancy weight (55 kg versus 63 kg) than the lactating mothers (n = 14). Body weight, height, waist and hip measurements, 3-d dietary and activity records, skin-fold thickness from triceps, suprailiac, midthigh, and midupper arm circumference, and total body composition were evaluated at three time periods (at delivery, at 6 wk, and at 12 wk postpartum). Total body composition for bone mineral, lean, and fat mass was measured by dual energy x-ray absorptiometry. At delivery and 6 wk postpartum, the weights and heights were similar between the two groups. By 12 wk postpartum, the formula-feeding group had a weight loss that was different from delivery, 66 +/- 10 kg to 59 +/- 8 kg, P < 0.03. There was no significant weight change in the lactating group during the study. The weight loss consisted of more lean mass than fat mass. The total body bone mineral content did not differ between the two groups during the study. Both groups had reduction in their waist size from delivery to 12 wk postpartum. But only the non-lactating mothers had reductions in their hip and midthigh measurements. There were no changes between the two groups in the skin-fold measurements. Lactating mothers had a higher total daily calories (1974 +/- 318 versus 1464 +/- 178 calories, P < 0.002) and fat intake (63 +/- 14 versus 47 +/- 9 g, P < 0.02) than the non-lactating mothers. The energy expenditure was similar between both groups. In conclusion, during the first 12 wk postpartum, non-lactating mothers who were younger and weighed less prepregnancy lost body weight and had more waist, hip, and midthigh size reductions compared to lactating mothers.

Body composition changes during lactation are highly variable among women

Changes in body weight and composition in response to the metabolic load imposed by lactation are highly variable among and within diverse populations. In most reports, rates of weight loss did not differ between lactating and nonlactating women. Despite differences in the hormonal milieu between lactating and nonlactating women, only subtle short-term differences were observed in postpartum changes in body composition. Regional patterns of fat deposition and mobilization did not differ between lactating and nonlactating women in most studies. Changes in body composition during lactation are responses to a sequence of complex neuroendocrine and biochemical stimuli that may be significantly modified by environmental factors. Gestational weight gain was the strongest determinant of postpartum weight and fat mass change, which supports the premise that biological mechanisms are aimed at restoring prepregnancy body weight and composition.

The effects of lactation on the mother

Undernourished mothers are likely to have limited fat reserves to draw on during lactation. In order to supply nutrition to her child the mother may therefore become more malnourished and suffer from bone resorption. Repeated or overlapping pregnancies with lactation are likely to compound the issue. Little research has been carried out into the health of mothers while breast feeding, or subsequently. There are theoretical reasons to think that the malnourished mother in the developing world may be particularly vulnerable, but no studies appear to have been undertaken. Investigations in the developed world have concentrated on cancers of the reproductive organs and shown consistent evidence in large case-control studies for a reduced risk of pre-menopausal breast cancer in mothers with a history of prolonged breast feeding. In contrast there have been a number of studies in the developed world concerned with emotional well-being with some indications that mothers who breast feed are more likely to be depressed and are less likely to be positive about their baby.

Factors related to body weight changes during and after pregnancy: the Stockholm Pregnancy and Weight Development Study

The Stockholm Pregnancy and Weight Development Study is a prospective study of body weight changes in women, whose maternity unit charts were reviewed and who were then invited for a 1-year follow-up, including weigh-in sessions and questionnaires on dietary habits, physical activity and socio-demographic factors. Total weight gain during pregnancy was related to weight gain already during the first trimester. Women reporting previous weight cycling had slightly higher weight gain during pregnancy. Successful return towards pre-pregnancy weight was found more often in women with regular breakfast and lunch habits. Lactation had only a small effect on weight loss after delivery, independent of eating habits. Lack of physical activity was more common in women who had low lactation scores. Twenty-eight percent reported an increased interest in sweets during pregnancy; these women increased 1 to 2 kg more than others in weight during pregnancy. Postpartum weight retention was more affected by lifestyle changes during and after pregnancy than by factors before pregnancy.

Maternal nutritional status may be stressed by seasonal fluctuations in food availability: evidence from rural women in Kenya

The effect of seasonal changes in household food availability on the dietary intakes and the nutritional status of 24 lactating women from smallholder rural households in Nakuru district Kenya, were investigated over a 15-month period in 1992/93 agricultural cycle. Dietary intakes and body weights were measured on monthly basis. Significant seasonal differences were found in intakes of calcium, vitamin A, vitamin C, riboflavin, and niacin respectively (P < 0.01), as well as in the intake of protein, iron, and thiamin (P < 0.05), but not with energy and fat intake. Large interseasonal weight losses of 5.6 kg (about 9%) at the rate of 1.1 kg/month, were observed between baseline measurements and the peak of the lean months when the energy intakes were 36.7 kcal/kg/day and protein at 1.1 g/kg/day. About 50% of the lost weight (2.8 kg) were recovered during the harvest months of January and February, when energy intakes improved to 41.0 kcal/kg/day, and protein to 1.2 g/kg/day. However, further weight losses of 1.6 kg or 0.5 kg/month occurred in the immediate postharvest months between March and June. While much of the weight loss may have been due to reduced energy intake during periods of food scarcity, part of the lost weight may have been due to increased energy requirement as a result of lactation and to increased physical activities. Further investigations are recommended.

Subcutaneous fat changes in low-income lactating mothers and growth of breast-fed infants

OBJECTIVE

We studied changes in body fat of lactating mothers and its relationship to milk fat and growth of exclusively breast-fed infants during the first 3 months of life.

METHOD

Changes in body fat measured by body mass index (BMI) and skinfold thickness (triceps, suprailiac, subscapular, pectoral) of 39 low socioeconomic status women were measured every 15 days during the first 3 months postpartum. Milk fat concentrations and growth of exclusively breast-fed infants were followed at the same intervals. Attained growth (ponderal and linear) of infants was analyzed through multivariate analyses against changes in maternal adiposity (BMI and sum of skinfolds), weight, and milk fat concentrations.

RESULTS

There was a decrease in maternal skinfold thickness from the 15th day postpartum. Milk fat concentrations decreased significantly only at the second month of lactation.

CONCLUSION

Statistical model adjustments for duration of study, milk fat concentration, and birth weight of infants explained 88% of variance in infant growth (r2 = 0.886, p = 0.0001).

Trends in eating patterns, physical activity and socio-demographic factors in relation to postpartum body weight development

'The Stockholm Pregnancy and Weight Development Study' was conducted to identify risk factors for postpartum weight retention, such as dietary habits, physical activity and socio-demographic factors. The body weight development of 1423 pregnant women was studied prospectively from the beginning of the pregnancy until 1 year postpartum. Data were collected from routine pregnancy records and from questionnaires 6 and 12 months postpartum. Mean weight retention 1 year postpartum was 0.5 kg compared with the prepregnancy body weight. A 'trend method' was constructed to identify a number of pre-defined major patterns of behaviour. The weight retention 1 year postpartum was greater in women who (a) increased their energy intake during and after pregnancy, (b) increased their snack eating after pregnancy to three or more snacks/d, and (c) decreased their lunch frequency starting during or after the pregnancy. Women who had retained > or = 5 kg 1 year postpartum were more seldom physically active in their leisure time throughout the study period compared with women with a smaller weight gain. Postpartum weight retention correlated negatively with the degree of physical activity in the second half year postpartum. These results indicate that postpartum weight retention is more affected by a change in lifestyle during, and above all after, pregnancy than by factors before pregnancy.

Breast-feeding reduces maternal lower-body fat

The effect of breast-feeding on maternal anthropometric measures during the first 6 postpartum months was studied in 24 women. Mothers, who were seen in the hospital shortly after delivery and at monthly intervals thereafter, kept a record of their infant-feeding practices and provided three 24-hour dietary recalls per month. The women were placed in one of three groups according to their infant-feeding practices: breast-feeding exclusively, combination of breast- and formula-feeding, and formula-feeding only. Changes in anthropometric variables at 6 months postpartum were similar in the three groups, but mothers who breast-fed exclusively or partially had significantly larger reductions in hip circumference measurements (3.6% and 3.1%, respectively) and were less above their prepregnancy weights at 1 month postpartum (7.8% and 8.5% above prepregnancy weight, respectively) than mothers who fed formula exclusively (0.68% reduction in hip circumference and 13.7% above prepregnancy weight). Our findings indicate that a woman's choice of infant-feeding practice influences postpartum anthropometric changes, but these effects may be temporary.

Body mass index and duration of breast feeding: a survival analysis during the first six months of life

STUDY OBJECTIVE

The aim was to determine whether excess weight in lactating women is associated with earlier cessation of breastfeeding.

DESIGN

The study was to prospective cohort analysis using a community sample of women.

SETTING

Geelong the regional centre of the Barwon Region of Victoria, Australia, in 1984-85.

SUBJECTS

All women who were breast feeding and whose first infant was born between 1 May 1984 and 30 April 1985 were asked to participate. Of these, 739 women participated, a response rate of 81%.

MAIN RESULTS

Smoking, mother's age and occupation, the time the infant was first put to the breast, and mother's body mass index at one month postpartum all exerted statistically significant independent effects on the duration of breast feeding, assessed using Cox's proportional hazards regression modelling. The strongest effects were for smoking, with an adjusted relative risk for cessation of breast feeding of 2.5 (95% CI 1.9 to 3.1) for 10 cigarettes per day v no smoking, and maternal age, with relative risk of 2.2 (95% CI 1.5 to 3.1) for a 20 year old mother relative to a 30 year old. The relative risk for women with a body mass index above 26 was 1.5 (95% CI 1.1 to 2.0).

CONCLUSIONS

Excess weight at one month postpartum, as determined by a body mass index above the normal range, was found to be an independent risk factor for early cessation of breast feeding and together with smoking, maternal age, occupation, and the time the infant is first put to the breast can be used to identify, early in the postpartum period, those women most likely to benefit from counselling in order to breast feed their infants successfully.

Maternal body composition: methods for measuring short-term changes

The measurement of short-term changes in maternal body composition during the post-partum period under field conditions poses many problems: (1) body composition techniques depend on the constancy of the proportions of components or their physical properties and are less suitable for measuring changes; (2) many of the techniques require expensive, technically sophisticated apparatus that is inappropriate to field conditions in many countries; (3) changes in body composition affect some areas of the body more than others so regional as well as whole body approaches are required. The measurements of body weight, triceps and subscapular skinfold thicknesses and upper arm circumference are essential measurements. These can be supplemented with further skinfold thicknesses and circumferences, and possibly body density and body water measurements. There is little to be gained by transforming anthropometric variables into whole body composition indices in these circumstances.