Breastfeeding and diabetes have a close relationship - breastfeeding has an impact on pre-existing and potential diabetes and diabetes has a impact on breastfeeding. Lactation may be delayed or impaired for reasons both of diabetes and obesity, so women in the diabetic spectrum need special consideration and attention to breastfeeding and lactation assistance.

Gestational diabetes mellitus (GD)

• mothers who had GD and suppress lactation have higher serum glucose than had they breastfed
• suppressing lactation has an immediate detrimental effect on their glucose tolerance and lasting effects on maternal metabolic profiles ¹
• mothers who had GD and suppress lactation will significantly increase their risk of developing Type 2 diabetes ^{1 2}

Type 2 diabetes mellitus

• Being artificially fed in infancy is associated with an increased risk of Type 2 diabetes. ³
• Due to their decreased glucose metabolism and altered metabolic profiles women who suppress lactation do not receive the protection that delays or prevents Type 2 diabetes mellitus in women who breastfeed their babies.
• Being obese and suppressing lactation significantly increases the risk of developing Type 2 diabetes mellitus. ²

Type 1 diabetes mellitus

• Onset of secretory activation (lactogenesis II) may be delayed. ⁴
• Being artificially fed as an infant significantly increases the risk of developing Type 1 diabetes mellitus. ^{5 6 7}
• Glucose use increases during lactation; lactating mothers can reduce their insulin by 25% or more of pre-pregnancy dose, while increasing their carbohydrate intake. Insulin requirements of mothers who suppress lactation is greater. ^{8 9 10}

Obesity is a risk factor for diabetes. Both impact on breastfeeding.

• being artificially-fed correlates to obesity in childhood and adulthood ^{13 14 15}
  
• overweight and obesity increases obstetric complications and is associated with a greater risk of operative delivery

• mothers who artifically feed compared to those who breastfeed (>6 months) have

  • a 2 kg greater weight gain by 1 year postpartum
  • larger waist girth
  • greater weight gain 10-15 years later
    
    

• Lactation difficulty

  • lactogenesis II may be delayed ¹⁶
  • positioning the baby to facilitate good latching is more difficult
  • the greater the BMI the greater the risk of early cessation of breastfeeding compared to women with normal BMI
  • overweight and obese women are less likely to plan to breastfeed, initiate breastfeeding and wean earlier ¹⁷

  
  

Autoimmune thyroid dysfunctions are a common cause of both hyper- and hypo-thyroidism.

Graves' disease (hyperthyroid) and postpartum thyroiditis are two major causes of thyrotoxicosis in the postpartum period. Antithyroid drugs, propylthiouracil or methimazole, are the mainstay of the treatment of postpartum thyrotoxicosis and both are safe to take while breastfeeding. Radioiodine treatment is contraindicated during lactation. ¹⁸

There is a relatively high prevalence of hypothyroidism, especially subclinical hypothyroidism. Hypothyroidism is associated with insufficient breastmilk supply and may be one of the symptoms which alerts you to this condition. Thyroxine replacement therapy is safe for the breastfeeding baby and milk levels will improve once the mother becomes euthyroid.

Thyroid status varies considerably postpartum. Medication dosage may need adjusting during the postpartum months. Be mindful of symptoms such as fatigue, palpitations, weight loss, loss of concentration and depression. Facilitate medical review of the mother.

Hepatitis B (HBV)

With appropriate immunoprophylaxis, including hepatitis B immune globulin and hepatitis B vaccine, breastfeeding does not contribute to mother-to-child transfer of HBV. ^{19 20}
Prior to vaccination, concern of transmission of HBV via cracked nipples was speculated but not recorded.

Hepatitis C (HCV)

There is no evidence of mother-to-infant transmission of hepatitis C from breastfeeding.

Untreated, about 5-15% (1 in 20, to 1 in 7) of babies born to women who are HIV infected will become HIV-positive through breastfeeding.

Exclusive breastfeeding reduces the risk of transfer by about half for HIV +ve mothers.
Exclusive breastfeeding with the addition of HAART regime reduces the mother's viral load to virtually undetectable, with a 0% - 3% risk of her infant acquiring HIV - the higher failure rate being associated with non-compliance to the regime. ^{21 22}

When mixed feeding is practiced the artificial formula damages the gut permitting transfer of virus from breastmilk.
Note: Before giving a supplement to ANY breastfed baby consider the risk you are submitting the baby to should the mother unknowingly be HIV positive.

Unfortunately most HIV-infected women live in low-income countries and do not have the resources for safe replacement feeding. Breastfeeding, though not exclusive breastfeeding, is the cultural norm in those countries most affected by HIV. It has been found that adherence to feeding intention among HIV-infected women was higher in those who chose to exclusively breastfeed than those who replacement feed.²⁵

Reduction mammoplasty surgery which has involved severing large numbers of lactiferous ducts, removal of large amounts of glandular tissue, or severing the 4th intercostal nerve innervating the nipple/areola, will affect breastfeeding ability to varying degrees. (The 4th intercostal nerve is the stimulus for the milk ejection reflex, some severed ducts will re-anastomose)

Breast augmentation also has the potential to negatively affect breastfeeding because of severed 4th intercostal nerve and ducts with peri-areola incision method, and compression of glandular tissue with sub-glandular placement of implant.

Breastfeeding, milk transfer and the baby's condition should be closely monitored to ensure the baby continues to thrive. An antenatal consultation with a Lactation Consultant followed by close supervision of initial and ongoing breastfeeding management and early interventions to increase supply is important.

Some women need to take medications while breastfeeding. It is important to ensure the baby will not be harmed via breastmilk transfer of the medication. It is equally as important not to forfeit breastfeeding when there are safe, effective medications. In most cases, it is far preferable to continue breastfeeding with small amounts of drug present in milk rather than risk many more hazardous effects of infant formula feeding.

All medications transfer into breastmilk to some degree but very, very few medications are contraindicated during breastfeeding. As a general rule of thumb less than 1% of the maternal dose passes via the breastmilk to the baby. Up to 10% of maternal dose is usually considered to be safe. ²⁶

Several factors influence the ultimate medication dose which the infant will receive via breastmilk:

• the transfer of the drug into the breastmilk - influenced by specific drug properties such as maternal drug level reached, molecular weight, protein binding capacity.
  
• the uptake of the drug by the infant from the breastmilk - daily intake of infant, stomach acidity, gut absorption.
  

Everyone who prescribes medications for breastfeeding women should have access to a recent text that specifically reviews medications for mothers. This is the link to an excellent online resource. http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT . Bookmark this resource for future reference.

The known detrimental effect of artificial infant formula feeding for both mother and baby needs to be seriously considered prior to ceasing breastfeeding due to maternal medication use. An alternative drug should be sought if the one usually prescribed is contraindicated.

When you are happy that you've understood all the information in this topic you will be ready to complete the Module 8 Assessment. To do this, go to the course opening page, scroll down to the Assessment section and choose Module 8.