Breastfeeding Part II: Facts and Myth-busting

Today we (finally!) sit down with Part II of our breastfeeding special with Dr. Erin Cleary to cover myths, facts, and advantages of breastfeeding.

There are only three main contraindications to breastfeeding:
1. In infants with galactosemia.
2. In mothers who are HIV+ in high-resource settings.
3. In mothers with human T-cell lymphoma virus.

There are a number of relative contraindications to breastfeeding:

  • In a mother with Hepatitis A until she receives gamma globulin.

  • In a mother with Hepatitis B until the infant receives HBIG and HepB vaccine.

  • In a mother with Hepatitis C if coinfections present, such as HIV.

  • In a mother with Varicella zoster (Chicken pox) while mother is infectious.

  • In a mother with Active TB until mother has received 2+ weeks treatment

  • In a mother with influenza

    • if the mother has been afebrile without antipyretics for >24 hours, and the mother is able to control her cough and respiratory secretions.

    • Oseltamivir or Tamiflu is poorly excreted in breastmilk

  • In patients abusing IV drugs.

  • In patients using marijuana:

    • (THC), the main compound in marijuana, is present in human milk up to eight times that of maternal plasma levels, and metabolites are found in infant feces, indicating that THC is absorbed and metabolized by the infant

    • Several preclinical studies highlight how even low to moderate doses during particular periods of brain development can have profound consequences for brain maturation, potentially leading to long-lasting alterations in cognitive functions and emotional behaviors

    • Breastfeeding mothers should be counseled to reduce or eliminate their use of marijuana to avoid exposing their infants to this substance and advised of the possible long-term neurobehavioral effects from continued use

Common Breastfeeding Myths/Misconceptions:


  • You should breastfeed if you have mastitis, emptying the breast prevents stasis of milk

You can breastfeed in setting of acute respiratory, urinary, GU infections, continuation of BF acceptable

Imaging Sudies

  • You can breastfeed if… You need medical imaging.

    • XRays do not affect milk

    • Mammograms may be harder to interpret when a patient is lactating, but this should not be a reason to defer recommended diagnostic imaging

    • CT/MRI with or without contrast do not impact breastmilk

    • XRays with contrast dye or imaging with radioactive material are also OK

    • Exception: thyroid scan using I-131

      • I-131 concentrates in breastmilk and at high levels can suppress baby’s thyroid function (or even destroy the thyroid) and increase risk of thyroid cancer.

      • Therefore it is important that breastfeeding be discontinued until breastmilk levels are safe (this depends upon the dose and ranges from 8 days to 106+ days). The half-life for I-131 is 8.1 days.

      • Hale recommends that when I-131 is used, breastmilk samples should be tested with a gamma (radiation) counter before breastfeeding is resumed to ensure that radiation in the milk has returned to safe levels.

  • You can breastfeed if… You are pregnant!  

    • Increasing progesterone will decrease supply and cause breast/nipple sensitivity.  

    • Mature milk will be replaced by colostrum in the 2nd trimester.

    • Tandem feeding includes breastfeeding a newborn and toddler

  • You can breastfeed if… You’ve had general anesthesia.  As soon as you are awake enough to hold the baby, the medication has metabolized and breastfeeding is safe.

  • You can breastfeed if… You are on maintenance medications such as methadone and buprenorphine

    • There is a reduction in severity and duration of treatment of NAS when mothers on these medications breastfeed

  • You can breastfeed if… You have an occasional alcoholic beverage

    • Alcohol concentration in the blood is in steady state with the milk, so delaying nursing or pumping until more alcohol is metabolized can limit exposure

  • If direct breastfeeding is interrupted due to temporary separation of mother and child for any reason, the breastfeeding mother should be encouraged and supported to regularly express her milk.

    • Expression and storage of milk allows the infant to continue to receive milk if appropriate, and prevents stasis of milk and mastitis

In the setting of infection, prior to expressing breast milk, mothers should wash their hands well with soap and water and, if using a pump, follow recommendations for proper cleaning.

Breastfeeding Part I

Today we start a two part series on breastfeeding with Dr. Erin Cleary, Assistant Professor of Obstetrics and Gynecology and Clinician Educator at the Warren Alpert Brown School of Medicine. She’s also the incoming MFM fellow at the Ohio State University — so look out for her in July, Buckeye listeners!

Also, thank you Dr. Daniel Ginn, our first Patreon sponsor — and apologies for the dad joke with your name!

We start today with a discussion of the anatomy of the breast, and in particular with lactation. At the bottom of this post is a corresponding Netter image to guide your listening.

The physiology of lactation is somewhat confusing, but in bulleted summary:
Lactogenesis I Early in pregnancy, human placental lactogen, prolactin, and chorionic gonadotropin contribute to maturation of the breast tissue to prepare for lactogenesis.

  • In the second trimester, secretory material which resembles colostrum appears in the glands.  A woman who delivers after 16 weeks gestation can be expected to produce colostrum.

  • Differentiated secretory alveolar cells develop at the ends of the mammary ducts under the influence of prolactin.  Progesterone acts to inhibit milk production during pregnancy. This makes sense from a viewpoint of energy expenditure- grow your baby first in utero, then switch to focus on growing it with milk.

Lactogenesis II is the onset of copious milk production at delivery.  In all mammals, it is associated with a drop in progesterone levels; in humans, this occurs during the 1st 4 days postpartum, with “milk coming in” by day 5

  • During the next 10 days, the milk composition changes to mature milk.  Establishing this supply is Lactogenesis III, and is NOT a hormonally-driven process like Lactogenesis I or II. Rather, this is supply/demand-driven with expression of milk

  • When the milk is not removed, the increased pressure lessens capillary blood flow and inhibits the lactation process.  Lack of sucking stimulation means lack of prolactin release from the pituitary.

Next week, we’ll be back again with Dr. Cleary discussing breastfeeding myths and contraindications, so stay tuned!

Netter’s Anatomy. Copyright Elsevier texts.