A twin study of breastfeeding with a preliminary genome-wide association scan

A history of depression and prenatal depression are associated with a lower likelihood of breastfeeding initiation and maintenance, and more breastfeeding problems

PURPOSE

This study tests the hypotheses that lifetime history of depression, and prenatal depression, are associated with a reduced likelihood of breastfeeding initiation (giving the baby any breastmilk during the first week of life) and breastfeeding maintenance (giving the baby breastmilk for at least 6 months), and a greater likelihood of reporting breastfeeding problems.

METHODS

We analyzed data from the Norwegian Mother, Father, and Child cohort study (MoBa), N = 78,307. Mothers reported a lifetime history of depression during the second trimester of pregnancy, and current symptoms of depression during the third trimester using the Hopkins Symptoms Checklist short version (SCL-8). At six months postpartum, mothers self-reported breastfeeding initiation, maintenance, and difficulties.

RESULTS

Using binary logistic regression analyses, we report that a lifetime history of depression is associated with a lower likelihood of breastfeeding initiation (OR = 0.751, 95%CI = 0.650-0.938), breastfeeding maintenance (OR = 0.712, 95%CI = 0.669-0.785), and a greater likelihood of breastfeeding difficulties (OR = 1.86, 95%CI = 1.72-2.06). Similarly, prenatal depression was associated with a lower likelihood of breastfeeding initiation (OR = 0.904, 95%CI = 0.878-0.929), breastfeeding maintenance (OR = 0.929, 95%CI = 0.920-0.938), and a greater likelihood of breastfeeding difficulties (OR = 1.10, 95%CI = 1.09-1.12). Results remained largely unchanged when covaried for several confounding variables, including medication use.

CONCLUSION

We provide novel evidence that pre-conception and prenatal symptoms of depression are associated with breastfeeding outcomes. This information could be used to identify women very early in pregnancy who may need additional support with breastfeeding. There is also a need to fully understand the biopsychosocial mechanisms that mediate the relationship between depression prior to birth and breastfeeding outcomes.

Analysis of gene expression from human breastmilk cells: A comparison between low and high producers, and the influence of anxiety and depression on milk production, gene expression and bacterial production

Background

Breastmilk is considered the gold standard of infant nutrition. Many mothers have difficulty with breastfeeding and over 50% of women stop due to perceived low production.

Aims and methods

Our study compared gene expression in 8 samples of low and high producers of milk. All subjects were administered GAD-7 and PHQ-9 questionnaires. Low-producers were all found to have more depression and anxiety compared to high-producers.

Results

We did not find significant differences between gene expression between low and high milk producers. Only 5 of 8 samples contained a significant number of human cells. We did find differences in the amount of various bacterial populations.

Conclusion

Our results indicate that gene expression in breastmilk is complicated by collection methods. We recommend that even though some women produced less than 600 ml of milk over a 24-hour period of time, due to the nature of the bacteria found in milk they try to breastfeed as much as they can for the health benefits of their infants. the rich bacterial diversity in all patients including the low producers strongly suggests that even women producing lesser quantities of milk confer their children numerous benefits by breastfeeding them.

The Genetics and Genomics of Asthma

Asthma is a common, clinically heterogeneous disease with strong evidence of heritability. Progress in defining the genetic underpinnings of asthma, however, has been slow and hampered by issues of inconsistency. Recent advances in the tools available for analysis-assaying transcription, sequence variation, and epigenetic marks on a genome-wide scale-have substantially altered this landscape. Applications of such approaches are consistent with heterogeneity at the level of causation and specify patterns of commonality with a wide range of alternative disease traits. Looking beyond the individual as the unit of study, advances in technology have also fostered comprehensive analysis of the human microbiome and its varied roles in health and disease. In this article, we consider the implications of these technological advances for our current understanding of the genetics and genomics of asthma.

No evidence of association of oxytocin polymorphisms with breastfeeding in 2 independent samples

Oxytocin has an important function in breastfeeding via its role in the milk ejection reflex and in attachment and bonding processes. Genetic factors account for a significant part of the individual differences in breastfeeding behavior. OXT and OXTR have been proposed as gene candidates for breastfeeding. Previous studies have focused on certain single-nucleotide polymorphisms (SNPs) within these genes, finding null or inconsistent results. The present study analyses the associations between a wide coverage of polymorphisms in OXT and OXTR and breastfeeding duration from 2 large and independent unselected samples comprising a total of 580 and 2112 female twin mothers from the Murcia Twin Registry (Spain) and QIMR Berghofer Medical Research Institute (Australia), respectively. A total of 19 SNPs in OXT and 137 in OXTR SNPs were covered in both samples. Effects of the OXT and OXTR polymorphisms on breastfeeding duration were calculated by means of linear regression controlling for age at survey time, educational level, interaction between age and educational level and principal components of genetic ancestry. The analyses were conducted independently in the 2 samples and also meta-analyzed. Although some SNPs were associated at an alpha level of .05 with breastfeeding, they did not survive multiple testing correction. We conclude that SNPs within or nearby OXT and OXTR are unlikely to have large effects on breastfeeding behavior.

Genetic loci associated with coronary artery disease harbor evidence of selection and antagonistic pleiotropy

Traditional genome-wide scans for positive selection have mainly uncovered selective sweeps associated with monogenic traits. While selection on quantitative traits is much more common, very few signals have been detected because of their polygenic nature. We searched for positive selection signals underlying coronary artery disease (CAD) in worldwide populations, using novel approaches to quantify relationships between polygenic selection signals and CAD genetic risk. We identified new candidate adaptive loci that appear to have been directly modified by disease pressures given their significant associations with CAD genetic risk. These candidates were all uniquely and consistently associated with many different male and female reproductive traits suggesting selection may have also targeted these because of their direct effects on fitness. We found that CAD loci are significantly enriched for lifetime reproductive success relative to the rest of the human genome, with evidence that the relationship between CAD and lifetime reproductive success is antagonistic. This supports the presence of antagonistic-pleiotropic tradeoffs on CAD loci and provides a novel explanation for the maintenance and high prevalence of CAD in modern humans. Lastly, we found that positive selection more often targeted CAD gene regulatory variants using HapMap3 lymphoblastoid cell lines, which further highlights the unique biological significance of candidate adaptive loci underlying CAD. Our study provides a novel approach for detecting selection on polygenic traits and evidence that modern human genomes have evolved in response to CAD-induced selection pressures and other early-life traits sharing pleiotropic links with CAD.

Biological underpinnings of breastfeeding challenges: the role of genetics, diet, and environment on lactation physiology

Lactation is a dynamic process that has evolved to produce a complex biological fluid that provides nutritive and nonnutritive factors to the nursing offspring. It has long been assumed that once lactation is successfully initiated, the primary factor regulating milk production is infant demand. Thus, most interventions have focused on improving breastfeeding education and early lactation support. However, in addition to infant demand, increasing evidence from studies conducted in experimental animal models, production animals, and breastfeeding women suggests that a diverse array of maternal factors may also affect milk production and composition. In this review, we provide an overview of our current understanding of the role of maternal genetics and modifiable factors, such as diet and environmental exposures, on reproductive endocrinology, lactation physiology, and the ability to successfully produce milk. To identify factors that may affect lactation in women, we highlight some information gleaned from studies in experimental animal models and production animals. Finally, we highlight the gaps in current knowledge and provide commentary on future research opportunities aimed at improving lactation outcomes in breastfeeding women to improve the health of mothers and their infants.