Kathleen M. Rasmussen

Background: Being breastfed has established benefits for infant health, but its long-term effects on adult diseases, including cancer, remain underexplored. We examined associations between being breastfed in infancy and the risks of common cancers. Methods: Data from 339,115 participants (191,117 women) enrolled in the UK Biobank with self-reported breastfeeding data were linked to national cancer registries. Cox models estimated sex-specific hazard ratios (HR) and 95% confidence intervals (CI) for the associations between being breastfed (ever/never) and risks of overall cancer as well as common cancer sites. Results: In total, 34,392 incident cancers (17,895 in women) were registered. The HR of overall cancer associated with being breastfed was 1.05 (95% CI 1.01–1.09) in women and 1.00 (95% CI 0.96–1-04) in men. In site-specific analysis being breastfed was associated with an increased risk of breast and ovarian cancer in women and a reduced risk of oesophageal cancer in men. Discussion: We found that having been breastfed was associated with a marginally increased risk of adult cancer in women, but we found no evidence of an association in men. These findings should be viewed within the study limitations, and do not outweigh the many benefits that breastfeeding provides.

Human milk sharing (HMS) is growing in popularity as an infant‐feeding strategy in the United States. HMS families are a hidden population because HMS is a nonnormative and stigmatized behaviour. Thus, gaining access to HMS participants is challenging, and research on this topic remains limited. In particular, little is known about the broader infant‐feeding behaviours of HMS parents. This study aimed to describe and compare the infant‐feeding behaviours and HMS practices among a network of HMS donors and recipients. A detailed online survey was distributed to HMS parents in the Washington, DC region. Bivariate analyses were used to summarize the data by donor/recipient status when possible. Group differences were tested using analysis of variance for continuous variables and χ² tests for categorical variables. Donors and recipients did not differ in their sociodemographic characteristics. Recipients were significantly more likely than donors to have experienced complications of labour and delivery, traumatic birth, postpartum depression or a negative breastfeeding experience. Donors and recipients did not differ significantly in their duration of lactation or HM‐feeding. Interestingly, 30% of recipients ever produced excess milk and 21% of donors ever had difficulty producing enough milk for their child. Compared with donors, recipients faced numerous maternal health challenges, but were still able to achieve a long duration of HM‐feeding. HMS recipients represent a vulnerable group who may benefit from additional psychosocial and lactation support to improve their health and breastfeeding outcomes. Additional research is needed to investigate the associations between HMS participation, infant‐feeding behaviours and lactation outcomes.

Little is known about the ability of the recently released Brazilian gestational weight gain (GWG) charts to predict the occurrence of adverse birth outcomes. We compared the new Brazilian weight gain charts with 3 international charts and determined their ability to predict the occurrence of small-for-gestational-age (SGA) and large-for-gestational-age (LGA) births in Brazilian women. A subsample of 6888 adult women (43,931 weight measurements) with singleton pregnancies from a nationwide, hospital-based cohort study conducted in 2011–2012 was analyzed. Selected percentiles from Brazilian GWG charts were compared with those from American, International Fetal and Newborn Growth Consortium for the 21^st Century study, and Lifecycle consortium charts. Sensitivity, specificity, and AUROC values for SGA and LGA births were estimated with 95% CIs using the classification of GWG below or above selected percentiles of each chart. The weight gain corresponding to a given percentile varied among the charts, especially for women with pre-pregnancy overweight and obesity. The proportions of women with GWG classified below or above selected percentiles were closest to the expected values for all pre-pregnancy BMI categories in the Brazilian and Lifecycle charts. At the 10th percentile, the highest sensitivity for SGA births was observed for the American charts at midpregnancy (36.8%) and the highest specificity was observed using the Brazilian charts in the first trimester (93.4%). At the 90th percentile, the highest sensitivity for LGA births occurred in midpregnancy for the Lifecycle charts (26.8%) and the highest specificity occurred in the American charts using total GWG (97.1%). All the AUROCs were under 0.5 for SGA births and ranged from 0.55 (first trimester) to 0.62 (total GWG) for LGA births. The charts differ in GWG trajectories, especially for women with overweight and obesity. The 4 charts had low predictive ability of SGA and LGA births and should not be considered as isolated screening tools for those outcomes.

It remains unknown whether maternal early life body size and changes in height and BMI from childhood to pregnancy are associated with risks of having a preterm delivery. We investigated whether a woman's birth weight, childhood height, BMI, and changes in height and BMI from childhood to pregnancy were associated with preterm delivery. We studied 47,947 nulliparous women born from 1940 to 1996 who were included in the Copenhagen School Health Records Register with information on birth weight and childhood heights and weights at ages 7 and/or 13 years. Gestational age was obtained from the Danish Birth Register, as was prepregnancy BMI, for 13,114 women. Deliveries were classified as very (22 to z score of 0, the RRs were 1.31 (95% CI, 1.11–1.54) for a z score of −1 and 1.18 (95% CI, 1.01–1.38) for a z score of +1. Short stature in childhood and adulthood was associated with higher risks of very and moderately preterm delivery. Changing from a BMI at the 85^th percentile at 7 years (US CDC reference) to a prepregnancy BMI of 22.5 kg/m² was associated with RRs of 1.12 (95% CI, 0.91–1.37) and 0.88 (95% CI, 0.78–0.99) for very and moderately preterm delivery, respectively, compared to a reference woman at the 50^th percentile at 7 years (22.5 kg/m² prepregnancy BMI). Maternal birth weight, childhood height, and BMI are associated with very and moderately preterm delivery, although in different patterns. Consistent short stature is associated with very and moderately preterm delivery, whereas normalizing BMI from childhood to pregnancy may reduce risks of having a very preterm delivery.

Prepregnancy body mass index (BMI) and gestational weight gain (GWG) are the most investigated indicators of maternal nutritional status, which is a modifiable factor that plays a vital role in maternal and infant health. This study describes prepregnancy BMI and GWG of 840,243 women with 2,087,765 weight observations in the Brazilian Food and Nutrition Surveillance System from 2008 to 2018. Prepregnancy BMI was classified according to the World Health Organization cut‐offs. Total GWG was calculated from weight measurements taken after 36 weeks of pregnancy and classified according to the Institute of Medicine guidelines. Temporal trends in prepregnancy BMI status were examined, and maps were used to evaluate changes in excessive GWG in each Brazilian federation unit. On overall, prepregnancy overweight and obesity increased from 22.6% to 28.8% and from 9.8% to 19.8%, respectively, between 2008 and 2018. The prevalence of excessive GWG rose from 34.2% to 38.7% during the same period and in 11 of the 27 Brazilian federation units between 2008 and 2016. Women with underweight showed the highest values for mean total GWG for all the compared years (overall variation from 12.3 to 13.1 kg), followed by those with normal weight (11.9 to 12.5 kg), overweight (10.1 to 10.9 kg) and obesity (from 8.2 to 8.9 kg). Within each BMI group, values remained fairly stable throughout the studied period for first‐ and second‐trimester GWG and total GWG. These results help to fill a significant gap in understanding the distribution of prepregnancy BMI and GWG in Brazilian women.

Background: One-fourth of women experience substantially higher weight years after childbirth. We examined weight change from prepregnancy to 18 months postpartum according to subsequent maternal risk of hypertension and cardiovascular disease (CVD). Methods and findings: We conducted a cohort study of 47,966 women with a live-born singleton within the Danish National Birth Cohort (DNBC; 1997–2002). Interviews during pregnancy and 6 and 18 months postpartum provided information on height, gestational weight gain (GWG), postpartum weights, and maternal characteristics. Information on pregnancy complications, incident hypertension, and CVD was obtained from the National Patient Register. Using Cox regression, we estimated adjusted hazard ratios (HRs; 95% confidence interval [CI]) for hypertension and CVD through 16 years of follow-up. During this period, 2,011 women were diagnosed at the hospital with hypertension and 1,321 with CVD. The women were on average 32.3 years old (range 18.0–49.2) at start of follow-up, 73% had a prepregnancy BMI 1–2 and >2 BMI units were associated with 25% (10%–42%), P = 0.001 and 31% (14%–52%), P < 0.001 higher risks of hypertension, respectively. These risks were similar whether weight gain presented postpartum weight retention or a new gain from 6 months to 18 months postpartum and whether GWG was below, within, or above the recommendations. For CVD, findings differed according to prepregnancy BMI. In women with normal-/underweight, weight gain >2 BMI units and weight loss >1 BMI unit were associated with 48% (17%–87%), P = 0.001 and 28% (6%–55%), P = 0.01 higher risks of CVD, respectively. Further, weight loss >1 BMI unit combined with a GWG below recommended was associated with a 70% (24%–135%), P = 0.001 higher risk of CVD. No such increased risks were observed among women with overweight/obesity (interaction by prepregnancy BMI, P = 0.01, 0.03, and 0.03, respectively). The limitations of this observational study include potential confounding by prepregnancy metabolic health and self-reported maternal weights, which may lead to some misclassification. Conclusions: Postpartum weight retention/new gain in all mothers and postpartum weight loss in mothers with normal-/underweight may be associated with later adverse cardiovascular health.

Maternal overweight (including obesity) is an established risk factor for gestational hypertension and pre-eclampsia. However, it is largely unknown whether body size before adulthood relates to these diseases. We examined whether childhood BMI (in kg/m²) and changes in BMI from childhood to adulthood were associated with gestational hypertension and pre-eclampsia. Using the Copenhagen School Health Records Register, we studied 49,600 women born between 1940 and 1996 with height and weight measurements at 7 y and/or 13 y who had their first singleton birth between ages 18 and 45 y. Women with gestational hypertension (n = 496) and pre-eclampsia (n = 1804) were identified from the International Classification of Disease codes in the Danish National Patient Register. Adult overweight (including obesity) was defined as a BMI ≥25. We used log-linear binomial regression to estimate risk ratios (RRs) and 95% CIs. At 13 y, as BMI increased above average (z score >0, or the 42nd percentile of the CDC BMI reference), RR for gestational hypertension was 1.66 (95% CI: 1.42, 1.94) and that for pre-eclampsia was 1.57 (95% CI: 1.46, 1.70) per BMI z score. In a subset of 13,160 women, development of overweight from childhood to adulthood and having overweight at both ages were associated with higher risks of the outcomes than in those with a normal BMI at both ages. No increased risks were observed in women whose BMI normalized from childhood to adulthood: RR was 2.04 (95% CI: 0.93, 4.47) for gestational hypertension and 1.11 (95% CI: 0.63, 1.93) for pre-eclampsia. Above-average childhood BMI values and development of overweight from childhood to adulthood were associated with increased risks of gestational hypertension and pre-eclampsia, whereas normalizing BMI from childhood to conception attenuated the risks. Thus, interventions aiming at normalizing BMI in girls with high values may be warranted to help prevent these obstetric diseases.

Prenatal micronutrient deficiencies are associated with negative maternal and birth outcomes. Multiple micronutrient supplementation (MMS) during pregnancy is a cost‐effective intervention to reduce these adverse outcomes. However, important knowledge gaps remain in the implementation of MMS interventions. The Child Health and Nutrition Research Initiative (CHNRI) methodology was applied to inform the direction of research and investments needed to support the implementation of MMS interventions for pregnant women in low‐ and middle‐income countries (LMIC). Following CHNRI methodology guidelines, a group of international experts in nutrition and maternal health provided and ranked the research questions that most urgently need to be resolved for prenatal MMS interventions to be successfully implemented. Seventy‐three research questions were received, analyzed, and reorganized, resulting in 35 consolidated research questions. These were scored against four criteria, yielding a priority ranking where the top 10 research options focused on strategies to increase antenatal care attendance and MMS adherence, methods needed to identify populations more likely to benefit from MMS interventions and some discovery issues (e.g., potential benefit of extending MMS through lactation). This exercise prioritized 35 discrete research questions that merit serious consideration for the potential of MMS during pregnancy to be optimized in LMIC.

The Guest Editors for the PLOS Medicine Special Issue on Maternal and Child Health & Nutrition discuss the published research in the context of global priorities for women's and children's health.