Effect of lactation on maternal body weight: a systematic review

Longer lactation duration is associated with decreased prevalence of non-alcoholic fatty liver disease in women

BACKGROUND & AIMS

Lactation lowers blood glucose and triglycerides, and increases insulin sensitivity. We hypothesized that a longer duration of lactation would be associated with lower prevalence of non-alcoholic fatty liver disease (NAFLD), which is the leading cause of chronic liver disease in the United States.

METHODS

Participants from the Coronary Artery Risk Development in Young Adults cohort study who delivered ≥ 1 child post-baseline (Y0: 1985-1986), and underwent CT quantification of hepatic steatosis 25 years following cohort entry (Y25: 2010-2011) were included (n = 844). The duration of lactation was summed for all post-baseline births, and NAFLD at Y25 was assessed by central review of CT images and defined by liver attenuation ≤ 40 Hounsfield Units after exclusion of other causes of hepatic steatosis. Unadjusted and multivariable logistic regression analyses were performed using an a priori set of confounding variables; age, race, education, and baseline body mass index.

RESULTS

Of 844 women who delivered after baseline (48% black, 52% white, mean age 49 years at Y25 exam), 32% reported lactation duration of 0 to 1 month, 25% reported >1 to 6 months, 43% reported more than 6 months, while 54 (6%) had NAFLD. Longer lactation duration was inversely associated with NAFLD in unadjusted logistic regression. For women who reported >6 months lactation compared to those reporting 0-1 month, the odds ratio for NAFLD was 0.48 (95% CI 0.25-0.94; p = 0.03) and the association remained after adjustment for confounders (adjusted odds ratio 0.46; 95% CI 0.22-0.97; p = 0.04).

CONCLUSIONS

A longer duration of lactation, particularly greater than 6 months, is associated with lower odds of NAFLD in mid-life and may represent a modifiable risk factor for NAFLD.

LAY SUMMARY

A longer duration of breastfeeding has been associated with multiple potential health benefits for the mother including reduction in heart disease, diabetes and certain cancers. In this study we found that breastfeeding for longer than 6 months was associated with a lower risk of non-alcoholic fatty liver disease in mid-life.

Challenges and Supports of Breastfeeding at Workplace in Indonesia

Due to increased number of women workers in Indonesia in the last decade, numbers of women living as a worker and a housewife have increased. This also increases the potential risk of breastfeeding discontinuation. Three months of maternal leave policy and inadequate lactation promotion support in workplace have been identified as factors that hinder lactating practices. The World Health Organization recommendation of 6 months of exclusive breastfeeding and joined regulation of three Indonesia ministers (Ministry of Health, Ministry of Labour, and Ministry of Women Empower) have failed to improve the exclusive breastfeeding rate among female workers in Indonesia due to the lack of a standardized guideline on lactation promotion at workplace. In addition, very limited or no studies have been conducted to evaluate the impact of workplace-based lactation intervention programs on exclusive breastfeeding rate among female workers. This is because the relationship of lactation with working performance and productivity could not motivate employer to invest in workplace-based lactation promotion facility or program.

Breastfeeding and maternal weight changes during 24 months post-partum: a cohort study

The relationship between breastfeeding and the loss of weight gained during pregnancy remains unclear. This study aimed to investigate the association between breastfeeding and maternal weight changes during 24 months post-partum. We studied a dynamic cohort comprising 315 women living in two cities in the state of Bahia, Brazil. The outcome variable was change in the post-partum weight; the exposure variable was the duration and intensity of breastfeeding. Demographic, socio-economic, environmental, reproductive and lifestyle factors were integrated in the analysis as covariates. The data were analysed using multiple linear regression and linear mixed-effects models. The average cumulative weight loss at 6 months post-partum was 2.561 kg (SD 4.585), increasing at 12 months (3.066 kg; SD 5.098) and decreasing at 18 months (1.993 kg; SD 5.340), being 1.353 kg (SD, 5.574) at 24 months post-partum. After adjustment, the data indicated that for every 1-point increase in breastfeeding score, the estimated average post-partum weight loss observed was 0.191 kg at 6 months (P = 0.03), 0.090 kg at 12 months (P = 0.043), 0.123 kg at 18 months (P < 0.001) and 0.077 kg at 24 months (P = 0.001). Based on these results, we concluded that despite the low expressiveness, the intensity and duration of breastfeeding was associated with post-partum weight loss at all stages of the study during the 24-month follow-up.

Impact of breastfeeding on maternal metabolism: implications for women with gestational diabetes

Lactating compared with nonlactating women display more favorable metabolic parameters, including less atherogenic blood lipids, lower fasting and postprandial blood glucose as well as insulin, and greater insulin sensitivity in the first 4 months postpartum. However, direct evidence demonstrating that these metabolic changes persist from delivery to postweaning is much less available. Studies have reported that longer lactation duration may reduce long-term risk of cardiometabolic disease, including type 2 diabetes, but findings from most studies are limited by self-report of disease outcomes, absence of longitudinal biochemical data, or no assessment of maternal lifestyle behaviors. Studies of women with a history gestational diabetes mellitus (GDM) also reported associations between lactation duration and lower the incidence of type 2 diabetes and the metabolic syndrome. The mechanisms are not understood, but hormonal regulation of pancreatic β-cell proliferation and function or other metabolic pathways may mediate the lactation association with cardiometabolic disease in women.

Study of Women, Infant Feeding, and Type 2 diabetes mellitus after GDM pregnancy (SWIFT), a prospective cohort study: methodology and design

Background

Women with history of gestational diabetes mellitus (GDM) are at higher risk of developing type 2 diabetes within 5 years after delivery. Evidence that lactation duration influences incident type 2 diabetes after GDM pregnancy is based on one retrospective study reporting a null association. The Study of Women, Infant Feeding and Type 2 Diabetes after GDM pregnancy (SWIFT) is a prospective cohort study of postpartum women with recent GDM within the Kaiser Permanente Northern California (KPNC) integrated health care system. The primary goal of SWIFT is to assess whether prolonged, intensive lactation as compared to formula feeding reduces the 2-year incidence of type 2 diabetes mellitus among women with GDM. The study also examines whether lactation intensity and duration have persistent favorable effects on blood glucose, insulin resistance, and adiposity during the 2-year postpartum period. This report describes the design and methods implemented for this study to obtain the clinical, biochemical, anthropometric, and behavioral measurements during the recruitment and follow-up phases.

Methods

SWIFT is a prospective, observational cohort study enrolling and following over 1, 000 postpartum women diagnosed with GDM during pregnancy within KPNC. The study enrolled women at 6-9 weeks postpartum (baseline) who had been diagnosed by standard GDM criteria, aged 20-45 years, delivered a singleton, term (greater than or equal to 35 weeks gestation) live birth, were not using medications affecting glucose tolerance, and not planning another pregnancy or moving out of the area within the next 2 years. Participants who are free of type 2 diabetes and other serious medical conditions at baseline are screened for type 2 diabetes annually within the first 2 years after delivery. Recruitment began in September 2008 and ends in December 2011. Data are being collected through pregnancy and early postpartum telephone interviews, self-administered monthly mailed questionnaires (3-11 months postpartum), a telephone interview at 6 months, and annual in-person examinations at which a 75 g 2-hour OGTT is conducted, anthropometric measurements are obtained, and self- and interviewer-administered questionnaires are completed.

Discussion

This is the first, large prospective, community-based study involving a racially and ethnically diverse cohort of women with recent GDM that rigorously assesses lactation intensity and duration and examines their relationship to incident type 2 diabetes while accounting for numerous potential confounders not assessed previously.

Lactation-associated postpartum weight changes among HIV-infected women in Zambia

BACKGROUND

There are concerns about effects of lactation on postpartum weight changes among HIV-infected women because low weight may increase risks of HIV-related disease progression.

METHODS

This analysis of postpartum maternal weight change is based on a trial evaluating the effects of shortened breastfeeding on postpartum mother-to-child transmission of HIV in Lusaka, Zambia, in which 958 HIV-infected women were randomized to breastfeed for a short duration (4 months) or for a duration of their own informed choosing (median 16 months). Among 768 women who met inclusion criteria, we compared across the two groups change in weight (kg) and the percent underweight [body mass index (BMI) <18.5] through 24 months. We also examined the effect of breastfeeding in two high-risk groups: those with low BMI and those with low CD4 counts.

RESULTS

Overall, women in the long-duration group gained less weight compared with those in the short-duration group from 4-24 months {1.0 kg [95% confidence interval (CI): 0.3-1.7] vs 2.3 kg (95% CI: 1.6-2.9), P = 0.01}. No association was found between longer breastfeeding and being underweight (odds ratio 1.1; 95% CI: 0.8-1.6; P = 0.40). Effects of lactation in underweight women and women with low CD4 counts were similar to the effects in women with higher BMI and higher CD4 counts. Women with low baseline BMI tended to gain more weight from 4 to 24 months than those with higher BMI, regardless of breastfeeding duration (2.1 kg, 95% CI: 1.3-2.9; P < 0.01).

CONCLUSIONS

In this study of HIV-infected breastfeeding women in a low-resource setting, the average change in weight from 4 to 24 months postpartum was a net gain rather than loss. Although longer duration breastfeeding was associated with less weight gain, breastfeeding duration was not associated with being underweight (BMI < 18.5). Weight change associated with longer breastfeeding may be metabolically regulated so that women with low BMI and at risk of wasting are protected from excess weight loss.

Duration of lactation and incidence of the metabolic syndrome in women of reproductive age according to gestational diabetes mellitus status: a 20-Year prospective study in CARDIA (Coronary Artery Risk Development in Young Adults)

OBJECTIVE

The objective of the study was to prospectively assess the association between lactation duration and incidence of the metabolic syndrome among women of reproductive age.

RESEARCH DESIGN AND METHODS

Participants were 1,399 women (39% black, aged 18-30 years) in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, an ongoing multicenter, population-based, prospective observational cohort study conducted in the U.S. Women were nulliparous and free of the metabolic syndrome at baseline (1985-1986) and before subsequent pregnancies, and reexamined 7, 10, 15, and/or 20 years after baseline. Incident metabolic syndrome case participants were identified according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. Complementary log-log models estimated relative hazards of incident metabolic syndrome among time-dependent lactation duration categories by gestational diabetes mellitus (GDM) adjusted for age, race, study center, baseline covariates (BMI, metabolic syndrome components, education, smoking, physical activity), and time-dependent parity.

RESULTS

Among 704 parous women (620 non-GDM, 84 GDM), there were 120 incident metabolic syndrome case participants in 9,993 person-years (overall incidence rate 12.0 per 1,000 person-years; 10.8 for non-GDM, 22.1 for GDM). Increased lactation duration was associated with lower crude metabolic syndrome incidence rates from 0-1 month through >9 months (P < 0.001). Fully adjusted relative hazards showed that risk reductions associated with longer lactation were stronger among GDM (relative hazard range 0.14-0.56; P = 0.03) than non-GDM groups (relative hazard range 0.44-0.61; P = 0.03).

CONCLUSIONS

Longer duration of lactation was associated with lower incidence of the metabolic syndrome years after weaning among women with a history of GDM and without GDM, controlling for preconception measurements, BMI, and sociodemographic and lifestyle traits. Lactation may have persistent favorable effects on women's cardiometabolic health.