Breastfeeding And Gestational Diabetes, Part One: Vital Benefits to Mother and Baby

More and more research is showing how important breastfeeding is after a Gestational Diabetes (GD) pregnancy, both for mother and baby.

Yet research consistently also shows lower rates of breastfeeding after Gestational Diabetes.

Promoting and improving breastfeeding rates in GD mothers is one easy way to improve the long-term health of mothers and babies exposed to GD, yet there are still far too many barriers to it.

Let's start with the many benefits of breastfeeding after GD, both for mother and baby.

How Breastfeeding Helps After Gestational Diabetes

Image credit: Much 2014

Breastfeeding improves the mother's blood sugar and insulin levels very quickly post-partum, and improves glucose utilization. It may also improve pancreatic beta cell mass, proliferation, and function, which should improve the mother's capacity to produce insulin adequate to compensate for any insulin resistance.

GD women who breastfeed have lower rates of abnormal blood sugar at their 6-week follow-up glucose tolerance test postpartum.

Breastfeeding also lowers insulin levels and improves insulin sensitivity more long-term.

As a result, breastfeeding lowers a mother's risk for developing diabetes later in life.

Even only a short period of breastfeeding offers some protection. However, the more you breastfeed and the longer the duration, the more your risk for diabetes may be diminished. That's HUGE.

Image credit: Much 2014, adapted from Ziegler 2012

Look at the graph above. Although many women were lost to follow-up, there was a clear and strong trend towards less diabetes in the women who breastfed their babies for more than three months. 72.6% of those who did not breastfeed or who breastfed for three or fewer months developed diabetes by 15 years post-partum, vs. 42% of those who breastfed for more than three months.

And really, three months of breastfeeding isn't that long in the scheme of things. Studies that looked at moderately longer periods found much lower insulin levels and better insulin sensitivity in those that nursed more than 10 months.

And 10 months does not even meet the American Academy of Pediatric's recommendation to nurse at least a year, or the World Health Organization's recommendation to nurse at least two years. How much more protection might there be for longer periods of breastfeeding?

One very large 2005 study found that the risk for diabetes declined about 15% for each additional cumulative year of breastfeeding, and another 2008 study found that the relative risk for diabetes was 0.68 in those with 4 or more years of lifetime lactation duration.

Breastfeeding may also offer some degree of protection against certain types of cancer which GD mothers may be more at risk for, including breast, endometrial, ovarian and possibly pancreatic cancers.

Even more imporantly, long-term breastfeeding may also offer some protection against heart disease and mortality. 

Some studies have found lower rates of cardiovascular risk factors in women with long-term breastfeeding. Most importantly, research has shown that breastfeeding translates into fewer heart attacks and lower mortality rates too. That's also HUGE.

One theory to explain all this is that pregnancy induces temporary changes in glucose and lipid metabolism that are beneficial for baby but not for the mother, and that these changes are even more marked in women with Gestational Diabetes. In this theory, breastfeeding is nature's way of "re-setting" the mother's metabolism back to normal afterwards. If breastfeeding does not occur (or is brief), the mother's metabolism doesn't really return to normal and she is much more likely to develop diabetes, hypertension, and heart disease with time.

Although this is still just a theory at this point, it is a logical one, and one with some data to support its premise. Obviously, the human body is complex and many different factors play a role in the development of disease, but long-term breastfeeding may be an effective, low-cost, and extremely practical way to lower the risk for later disease.

Clearly, breastfeeding (and especially long-term breastfeeding) has important potential benefits for GD mothers.

Extra Benefits for GD Babies

Breastfeeding has so many benefits for all babies. We've known this for quite a while, yet it's surprising how often this does not get communicated well to pregnant women or the general public.

The general benefits of breastfeeding include lower risk for infections, asthma, diarrhea, ear infections, celiac disease, Sudden Infant Death Syndrome (SIDS), necrotizing enterocolitis in pre-term infants, and many other things. That's all pretty important right there.

But breastfeeding has extremely important immunological functions that are under-appreciated even among care providers. When in utero, the baby depends on the mother's placenta for immunological protection. After the baby is born, its own immunological system is quite immature. Nature designed breastfeeding to help bridge the gap between in utero protection and when the baby's own immunological system matures.

The first milk, colostrum, plays a vital role in "coating" the surface of the baby's intestines to help them be less vulnerable to pathogens. Later, human milk encourages the growth of the villi in the intestine and develops antibody responses specific to the pathogens the mother encounters. It also helps the baby strengthen and develop its own immuno-responses to pathogens, which may provide enhanced immuno-protection even after breastfeeding ends. Thus, breastfeeding is crucial in protecting the baby's immune system both short- and long-term. Its benefits do not end with weaning.

These are all important reasons to raise breastfeeding rates in the general population. However, there are additional potential benefits for babies of GD pregnancies.

The biggest benefit of breastfeeding after a GD pregnancy is that it lowers the risk of the baby developing diabetes as he/she grows to adulthood.

This is another HUGE advantage. Babies exposed to higher blood sugar rates in utero tend to have poorer glucose metabolisms, more insulin resistance, and more metabolic syndrome later in life.

If breastfeeding can prevent or delay many cases of metabolic syndrome and diabetes in a GD mother's offspring, it has tremendous public health implications for babies as well as mothers.

And this may be a particularly important finding for people of color, because of their increased risk for diabetes. One early study in a particularly vulnerable population (Pima Indians) found about half the risk for diabetes in adults who were breastfed for at least two months compared to those who were not. Imagine what the difference might be with longer periods of breastfeeding!

One study projected that if 90% of families in the U.S. breastfed exclusively for 6 months, about 911 deaths would be prevented each year. Of course, data projections like this are merely speculative, but even so, a clear trend in the statistical model implies that increasing breastfeeding rates would be a low-cost, effective strategy for improving public health in babies as well as in mothers.

And this may especially be true for babies of GD pregnancies.

Conclusion

Breastfeeding is a vital part of the so-called "fourth trimester" of pregnancy...and well beyond.

In other words, the mother's biological role in protecting her baby does not end with the baby's birth. It extends into breastfeeding and even beyond weaning.

Nature intended babies to be breastfed for significant periods of time in order to protect them while they are immunologically immature and to produce optimal and healthy growth and development. Nature also intended breastfeeding to benefit the mother by re-setting her metabolism and lowering her risk for heart disease and some cancers. Breastfeeding's benefits to both baby and mother do not end with weaning but appear to last for years afterwards.

Obviously, there are times when breastfeeding isn't possible, doesn't work out, or isn't wanted for various reasons, and it's good that we have substitutes available for these situations. Formula isn't "bad" or "evil," and it's a reasonably good substitute when human breastmilk is not available. Although uncommon, there are women who are truly unable to breastfeed and it's important that we have respect for that experience and support for those women even as we promote breastfeeding.

However, we must remember that Nature's design results in the most optimal outcomes and we subvert that design at the risk of significant harm on a population-wide basis. 

How much of our public health woes today are due to the widespread and very strong discouragement of breastfeeding by physicians in the last century? We may never know, but I would bet that at least some of the increase in diabetes and other problems we see today is at least partly due to the tremendous pressure on women from the mid-20th century not to breastfeed.

Even today, when most care providers at least pay lip service to the benefits of breastfeeding, many women are subtly discouraged from nursing or are told that there is little benefit to continuing to breastfeed past a few months. (Yep, I heard this one).

Even more alarming, despite evidence of EXTRA benefits to breastfeeding after a GD pregnancy, women with Gestational Diabetes have lower rates of breastfeeding than other women. 

Although some of this may have some basis in biological differences like PCOS (Polycystic Ovarian Syndrome), much of it is rooted in routine practices and interventions common during and after births in women with Gestational Diabetes. Yet care providers often fail to recognize that breastfeeding "failure" often begins with the interventions that occur during and after birth. 

There is much that can be done to raise breastfeeding rates in women with GD, if only caregivers and hospitals would recognize the role that common interventions plays in interfering with establishment of breastfeeding.

That's not to say that interventions should never take place. Sometimes interventions are truly necessary, especially in complicated cases of GD, but the reality is that they are often overused, and reducing them is a good first step in increasing breastfeeding rates. And even when interventions are truly necessary, there is much that can be done to protect and promote breastfeeding under less than ideal conditions, yet full implementation of these measures is lacking in many hospitals.

In our next post, we will discuss specifics on how to remove barriers and raise breastfeeding rates in women with GD. For the long-term health of babies and mothers, it is critical that we do this.


References

Breastfeeding and Short-Term Maternal Glucose Tolerance

Ir Med J. 2012 May;105(5 Suppl):31-6. Breast-feeding is associated with reduced postpartum maternal glucose intolerance after gestational diabetes. O'Reilly M, Avalos G, Dennedy MC, O'Sullivan EP, Dunne FP. PMID: 22838108

...We prospectively examined the prevalence of postpartum dysglycaemia after GDM and examined the effect of lactation on postpartum glucose tolerance. We compared postpartum 75g oral glucose tolerance test (OGTT) results from 300 women with GDM and 220 controls with normal gestational glucose tolerance (NGT). Breast-feeding data was collected at time of OGTT...The prevalence of persistent hyperglycaemia was significantly lower in women who breast-fed versus bottle-fed postpartum (8.2% v 18.4%, p < 0.001). Breast-feeding may confer beneficial metabolic effects after GDM and should be encouraged.

Diabetes Care. 2012 Jan;35(1):50-6. doi: 10.2337/dc11-1409. Epub 2011 Oct 19. Lactation intensity and postpartum maternal glucose tolerance and insulin resistance in women with recent GDM: the SWIFT cohort. Gunderson EP, Hedderson MM, Chiang V, Crites Y, Walton D, Azevedo RA, Fox G, Elmasian C, Young S, Salvador N, Lum M, Quesenberry CP, Lo JC, Sternfeld B,Ferrara A, Selby JV. PMID: 22011407

OBJECTIVE: To examine the association between breastfeeding intensity in relation to maternal blood glucose and insulin and glucose intolerance based on the postpartum 2-h 75-g oral glucose tolerance test (OGTT) results at 6-9 weeks after a pregnancy with gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: We selected 522 participants enrolled into the Study of Women, Infant Feeding, and Type 2 Diabetes (SWIFT), a prospective observational cohort study of Kaiser Permanente Northern California members...RESULTS:...Exclusive or mostly breastfeeding groups had lower prevalence of diabetes or prediabetes (P = 0.02). CONCLUSIONS: Higher intensity of lactation was associated with improved fasting glucose and lower insulin levels at 6-9 weeks' postpartum. Lactation may have favorable effects on glucose metabolism and insulin sensitivity that may reduce diabetes risk after GDM pregnancy.

Obstet Gynecol. 2012 Jul;120(1):136-43. doi: 10.1097/AOG.0b013e31825b993d. Influence of breastfeeding during the postpartum oral glucose tolerance test on plasma glucose and insulin.
Gunderson EP, Crites Y, Chiang V, Walton D, Azevedo RA, Fox G, Elmasian C, Young S, Salvador N, Lum M, Hedderson MM, Quesenberry CP, Lo JC, Ferrara A,Sternfeld B. PMID: 22914402

...Participants were enrolled in the Study of Women, Infant Feeding, and Type 2 Diabetes, a prospective observational cohort study of 1,035 Kaiser Permanente Northern California members who had been diagnosed with GDM...RESULTS: Of 835 lactating women, 205 (25%) breastfed their infants during the 2-hour 75-g OGTT at 6-9 weeks postpartum....CONCLUSION: Among postpartum women with recent gestational diabetes mellitus, breastfeeding an infant during the 2-hour 75-g OGTT may modestly lower plasma 2-hour glucose (5% lower on average) as well as insulin concentrations in response to ingestion of glucose.

Breastfeeding and Subsequent Maternal Diabetes

Diabetes Care. 2010 Jun;33(6):1239-41. doi: 10.2337/dc10-0347. Epub 2010 Mar 23. Parity, breastfeeding, and the subsequent risk of maternal type 2 diabetes. Liu B, Jorm L, Banks E. PMID: 20332359

...Using information on parity, breastfeeding, and diabetes collected from 52,731 women recruited into a cohort study, we estimated the risk of type 2 diabetes using multivariate logistic regression. RESULTS A total of 3,160 (6.0%) women were classified as having type 2 diabetes. Overall, nulliparous and parous women had a similar risk of diabetes. Among parous women, there was a 14% (95% CI 10-18%, P < 0.001) reduced likelihood of diabetes per year of breastfeeding. Compared to nulliparous women, parous women who did not breastfeed had a greater risk of diabetes (odds ratio 1.48, 95% CI 1.26-1.73, P < 0.001), whereas for women breastfeeding, the risk was not significantly increased. CONCLUSIONS: Compared with nulliparous women, childbearing women who do not breastfeed have about a 50% increased risk of type 2 diabetes in later life. Breastfeeding substantially reduces this excess risk.

Diabetes. 2012 Dec;61(12):3167-71. doi: 10.2337/db12-0393. Epub 2012 Oct 15. Long-term protective effect of lactation on the development of type 2 diabetes in women with recent gestational diabetes mellitus. Ziegler AG, Wallner M, Kaiser I, Rossbauer M, Harsunen MH, Lachmann L, Maier J, Winkler C, Hummel S. PMID: 23069624

...To investigate whether breastfeeding influences short- and long-term postpartum diabetes outcomes, women with GDM (n = 304) participating in the prospective German GDM study were followed from delivery for up to 19 years postpartum for diabetes development. All participants were recruited between 1989 and 1999. Postpartum diabetes developed in 147 women and was dependent on the treatment received during pregnancy (insulin vs. diet), BMI, and presence/absence of islet autoantibodies. Among islet autoantibody-negative women,breastfeeding was associated with median time to diabetes of 12.3 years compared with 2.3 years in women who did not breastfeed. The lowest postpartum diabetes risk was observed in women who breastfed for >3 months. On the basis of these results, we recommend that breastfeeding should be encouraged among these women because it offers a safe and feasible low-cost intervention to reduce the risk of subsequent diabetes in this high-risk population. 

Lactation Duration and Subsequent Maternal Diabetes

Eur J Endocrinol. 2013 Mar 15;168(4):515-23. doi: 10.1530/EJE-12-0939. Print 2013 Apr. Relationship between lactation duration and insulin and glucose response among women with prior gestational diabetes. Chouinard-Castonguay S, Weisnagel SJ, Tchernof A, Robitaille J. PMID: 23302255

...The study group comprised 144 women with a history of GDM between 2003 and 2010. Plasma insulin and glucose concentrations were obtained from a 75 g oral glucose tolerance test (OGTT). Total lactation duration (exclusive breastfeeding and breast and bottle-feeding) for all infants was self-reported in months. RESULTS: Mean age was 36.5±5.0 years. Time between delivery and metabolic testing was 4.0±1.9 years. Women breastfed for an average of 13.9±16.8 months. Most women (80.6%) reported a history of lactation...Compared with women who lactated for <10 months, women who lactated for ≥10 months had improved insulin sensitivity-secretion index, higher HOMA-IS and Matsuda indices, lower fasting and 2-h post-OGTT insulin concentrations as well as AUC for insulin, and lower incidence of impaired glucose intolerance (P≤0.05 for all). In multiple linear regression analyses, lactation duration emerged as an independent predictor of fasting insulin concentrations (β=-0.02) and insulin sensitivity indices (β=0.02) (P≤0.05 for all). CONCLUSIONS: These results suggest that longer duration of lactation is associated with improved insulin and glucose response among women with prior GDM.

JAMA. 2005 Nov 23;294(20):2601-10. Duration of lactation and incidence of type 2 diabetes. Stuebe AM1, Rich-Edwards JW, Willett WC, Manson JE, Michels KB. PMID: 16304074

...Prospective observational cohort study of 83,585 parous women in the Nurses' Health Study (NHS) and retrospective observational cohort study of 73,418 parous women in the Nurses' Health Study II (NHS II)...RESULTS: ...Among parous women, increasing duration of lactation was associated with a reduced risk of type 2 diabetes. For each additional year of lactation, women with a birth in the prior 15 years had a decrease in the risk of diabetes of 15% (95% confidence interval, 1%-27%) among NHS participants and of 14% (95% confidence interval, 7%-21%) among NHS II participants, controlling for current body mass index and other relevant risk factors for type 2 diabetes. CONCLUSIONS: Longer duration of breastfeeding was associated with reduced incidence of type 2 diabetes in 2 large US cohorts of women. Lactation may reduce risk of type 2 diabetes in young and middle-aged women by improving glucose homeostasis. 

Diabetologia. 2008 Feb;51(2):258-66. Epub 2007 Nov 27. Duration of breast-feeding and the incidence of type 2 diabetes mellitus in the Shanghai Women's Health Study. Villegas R1, Gao YT, Yang G, Li HL, Elasy T, Zheng W, Shu XO. PMID: 18040660

...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... RESULTS: 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 baselines....

Breastfeeding and Cardiovascular Implications

BMC Public Health. 2013 Nov 13;13:1070. doi: 10.1186/1471-2458-13-1070. A prospective population-based cohort study of lactation and cardiovascular disease mortality: the HUNT study. Natland Fagerhaug T1, Forsmo S, Jacobsen GW, Midthjell K, Andersen LF, Ivar Lund Nilsen T. PMID: 24219620

...In a Norwegian population-based prospective cohort study, we studied the association of lifetime duration of lactation with cardiovascular mortality in 21,889 women aged 30 to 85 years who attended the second Nord-Trøndelag Health Survey (HUNT2) in 1995-1997. The cohort was followed for mortality through 2010 by a linkage with the Cause of Death Registry...RESULTS:...Parous women younger than 65 years who had never lactated had a higher cardiovascular mortality than the reference group of women who had lactated 24 months or more (HR 2.77, 95% confidence interval [CI]: 1.28, 5.99)...CONCLUSIONS: Excess cardiovascular mortality rates were observed among parous women younger than 65 years who had never lactated. These findings support the hypothesis that lactation may have long-term influences on maternal cardiovascular health.

Breastfeeding and Maternal Cancer

Am J Clin Nutr. 2013 Oct;98(4):1020-31. doi: 10.3945/ajcn.113.062794. Epub 2013 Aug 21. Breastfeeding and ovarian cancer risk: a meta-analysis of epidemiologic studies. Luan NN1, Wu QJ, Gong TT, Vogtmann E, Wang YL, Lin B. PMID: 23966430

...We performed a meta-analysis to summarize available evidence of the association between breastfeeding and breastfeeding duration and EOC [ovarian cancer] risk from published cohort and case-control studies...RESULTS: Five prospective and 30 case-control studies were included in this analysis. The pooled RR for ever compared with never breastfeeding was 0.76 (95% CI: 0.69, 0.83), with moderate heterogeneity (Q = 69.4, P < 0.001, I(2) = 55.3%). Risk of EOC decreased by 8% for every 5-mo increase in the duration of breastfeeding (RR: 0.92; 95% CI: 0.90, 0.95). The risk reduction was similar for borderline and invasive EOC and was consistent within case-control and cohort studies. CONCLUSIONS: Results of this meta-analysis support the hypothesis that ever breastfeeding and a longer duration of breastfeeding are associated with lower risks of EOC....

Breastfeeding and Diabetes in Children

Am J Clin Nutr. 2006 Nov;84(5):1043-54. Does breastfeeding influence risk of type 2 diabetes in later life? A quantitative analysis of published evidence. Owen CG, Martin RM, Whincup PH, Smith GD, Cook DG. PMID: 17093156

...DESIGN: A systematic review of published studies identified 1010 reports; 23 examined the relation between infant feeding and type 2 diabetes in later life or risk factors for diabetes...RESULTS: Subjects who were breastfed had a lower risk of type 2 diabetes in later life than did those who were formula fed (7 studies; 76 744 subjects; odds ratio: 0.61; 95% CI: 0.44, 0.85; P = 0.003). Children and adults without diabetes who had been breastfed had marginally lower fasting insulin concentrations than did those who were formula fed (6 studies; 4800 subjects; percentage difference: -3%; 95% CI: -8%, 1%; P = 0.13); no significant difference in fasting glucose concentrations was observed...CONCLUSION: Breastfeeding in infancy is associated with a reduced risk of type 2 diabetes, with marginally lower insulin concentrations in later life, and with lower blood glucose and serum insulin concentrations in infancy.

Lower Rates of Breastfeeding in Women with Diabetes

Diabet Med. 2013 Sep;30(9):1094-101. doi: 10.1111/dme.12238. Epub 2013 Jun 21. Breastfeeding in women with diabetes: lower rates despite greater rewards. A population-based study. Finkelstein SA, Keely E, Feig DS, Tu X, Yasseen AS 3rd, Walker M. PMID: 23692476

...METHODS: A retrospective cohort analysis was conducted using data from four Ontario hospitals. Women who delivered a viable infant between 1 April 2008 and 31 March 2010 were included in the study...CONCLUSIONS: Women with insulin-treated diabetes had the poorest outcomes with respect to breastfeeding rates. Gestational and non-insulin-treated diabetes were associated with lower rates of breastfeeding in hospital, while gestational diabetes was additionally associated with lower breastfeeding rates on discharge.

Dtsch Med Wochenschr. 2008 Feb;133(5):180-4. doi: 10.1055/s-2008-1017493. [Breastfeeding in women with gestational diabetes]. Hummel S, Hummel M, Knopff A, Bonifacio E, Ziegler AG. PMID: 18213549

...METHODS: Breastfeeding habits (breastfeeding of any duration) were recorded of 257 mothers with gestational diabetes...who participated in a prospective post-partum study between 1989 and 1999 and compared to breastfeeding habits of 527 healthy mothers... all enrolled in the prospective BABYDIAB study between the years 1989 and 2000...RESULTS: Compared to children of healthy mothers, fewer children of mothers with gestational diabetes were breastfed (75% vs 86%; P<0.0001). Among breastfed children the duration of full or any breastfeeding was shorter in children of mothers with gestational diabetes (median for full breastfeeding 9 weeks. [mothers with gestational diabetes] vs. 17 weeks. [healthy mothers]; p<0.0001; median duration of any breastfeeding 16 weeks. vs. 26 weeks.; p<0.0001)...Full and any breastfeeding was shorter in women with insulin-dependent gestational diabetes than in those with diet-controlled gestational diabetes (full breast-feeding 4 weeks. vs. 12 weeks.; p<0.01 and any breastfeeding 10 weeks. vs. 20 weeks,; p<0.0001)....