Breastfeeding and Subsequent Risk of Gestational Diabetes
by Anne Eglash MD, IBCLC, FABM
The evidence is clear that breastfeeding reduces one’s future risk of type 2 diabetes. A study published in 2020 using data from the Diabetes & Women’s Health Study found that women in their 60’s with a history of GD experience a lower risk of type 2 diabetes in association with more cumulative years of breastfeeding. This is huge, since 1 out of every 9 women in the USA develop diabetes.
The authors of this week’s study investigated whether women with a history of GD would have a lower risk of GD with their next pregnancy based on duration and/or intensity of breastfeeding.
This study recruited 209 women in Sydney Australia during 2017-2019 who were over 20 weeks gestation in their second pregnancy after a diagnosis of GD with their first pregnancy. Using survey tools, they assessed the intensity and duration of breastfeeding with their first infant, with the highest intensity being exclusive breastfeeding. Twenty-three percent of the participants had a low breastfeeding intensity score, nursing for less than 3 months.
The majority of the participants were South Asian (52%), 16% were Caucasian, the rest Middle Eastern or Other. 70% of the 209 participants developed GD with their second pregnancy. The researchers found that participants who breastfed for more than 6 months were less likely to develop recurrent GD as compared to those who breastfed less than 6 months.
- Breastfeeding greater than 6 months led to a 32% decreased risk of GD with the subsequent pregnancy.
- Breastfeeding greater than 6 months led to a 18% decreased risk of GD with the subsequent pregnancy.
- Breastfeeding greater than 6 months was less effective in reducing the risk of recurrent GD for those mothers who needed medication such as insulin treatment.
- Breastfeeding for more than 6 months led to a significantly lower blood sugar during the 1 hour glucose tolerance test during the next pregnancy.
See the Answer
Gestational diabetes mellitus is associated with higher risk for developing type 2 diabetes. Breastfeeding is protective against the development of type 2 diabetes after gestational diabetes. There are no data regarding the effect of breastfeeding on the development of recurrent gestational diabetes.
Investigate the relationship of previous breastfeeding duration and intensity with the recurrence of gestational diabetes, and second pregnancy glucose tolerance test results.
We conducted a questionnaire-based pilot cohort study, enrolling 210 women during a subsequent second pregnancy, after a gestational diabetes-affected first pregnancy. Models for length and intensity of breastfeeding as predictors of the oral glucose tolerance test and for diagnosis of gestational diabetes in second pregnancy were fitted and then adjusted for possible confounders.
Recurrent gestational diabetes rate in the study cohort was 70% (n = 146). In a fully adjusted model high intensity breastfeeding was associated with a lower 2-hour glucose level on the oral glucose tolerance test (by 0.66 mmol/L, 95% CI [0.15–1.17]; p = 0.01) and breastfeeding greater than six months with a lower 1-hour glucose on the oral glucose tolerance test (by 0.67 mmol/L, 95% CI [0.16–1.19]; p = 0.01), compared to women who breastfed less intensively or for a shorter duration respectively. There was an 18% reduction in the risk of gestational diabetes if a woman breastfed for more than six months (RR 0.82, 95% CI [0.69–0.98]; p = 0.03). The association was attenuated in the fully adjusted model (RR 0.89, 95% CI [0.78–1.02]; p = 0.09).
We found the risk of recurrent gestational diabetes was reduced by both increased duration and intensity of breastfeeding. Antenatal lactation education should be embedded into care pathways for women diagnosed with gestational diabetes.
Breastfeeding longer than 6 months was associated with a 18% reduced risk of recurrent GD, not 32%.
The association of longer breastfeeding and reduced risk of recurrent GD was attenuated when the modeling adjusted for medical treatment. This may indicate that those with more advanced GD need more intense health intervention beyond breastfeeding ≥ 6 months in order to prevent recurrent GD, such as improvements in diet and exercise.
Among the participants who breastfed for less than 3 months, the most common reason for stopping was ‘I didn’t think I had enough milk’. We know that women with a history of insulin resistance, high BMI and/or GD are at risk for insufficient milk production. Lactating individuals with low milk production face more stress due to several reasons, such as the infants’ unwillingness to continue breast/chestfeeding, having to supplement, and/or worrying whether their infants are taking sufficient calories. These individuals need support to continue lactating even if their production cannot reach sufficiency, as the hormone changes associated with lactation help to reduce their risk of type 2 diabetes in the decades to come.