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Breastfeeding a Baby with PKU

Terry Grossmayer
New Lenox IL USA
From NEW BEGINNINGS, Vol. 15 No. 5, September-October 1998, p. 153,156

We provide articles from our publications from previous years for reference for our Leaders and members. Readers are cautioned to remember that research and medical information change over time.

Breastfeeding and mothering go hand in hand, wouldn't you agree? Can you picture yourself having a baby and not nursing? I sure couldn't. I am an advocate of breastfeeding. I nursed my first two children well into toddlerhood and enjoyed the usual benefits of breastfeeding. If you are a nursing mother, you know the list: a healthy baby, healthy mother, bonding, convenience. The advantages go on and on and many of us take the experience of breastfeeding for granted. After my recent experience, I will never take it for granted again. I now realize breastfeeding is a privilege, a sheer gift.

For most mothers and babies, breast is best, but in certain cases, the situation is more complicated. I found myself in a situation like this. Newborn screening revealed that our baby, Peter, was born with a metabolic disorder known as phenylketonuria (PKU). People born with this genetic disorder do not produce the enzyme needed to break down phenylalanine, an essential amino acid. The phenylalanine builds up in the bloodstream and causes severe mental retardation. By following a low-protein diet, people with PKU can lead totally normal lives. For the newborn, this means monitoring the level of phenylalanine in the blood so that the baby gets just the small amount needed for growth. A special low-phenylalanine formula is recommended for these babies. Since human milk is lower in phenylalanine than cow's milk formula, a mother can continue breastfeeding while supplementing her baby's diet with the low-phenylalanine formula. I asked the doctor how other mothers have managed to continue breastfeeding. She said that they often try, but their milk usually dries up for lack of stimulation. "Well," I thought, "that just isn't going to happen to me!"

Finding information about how to breastfeed a baby with PKU was difficult, but finding support to do it was not. My husband was a tremendous support for me because he had already seen what breastfeeding had done for our other children. My dear friend and my LLL Leader also supported me. Other friends who had breastfed sent letters and good wishes. When I questioned one wise friend about how to mother without breastfeeding, she said. "You are going to put that little face against your breast just as you would if you were breastfeeding and give him his bottle." Without support like this. I could never have done it.

I wanted Peter to breastfeed as much as possible and he did enjoy quite a bit of time at the breast. The whole key to keeping it going seemed to be to stabilize my production of milk. This was tricky because the number of daily nursings would fluctuate based on the results of Peter's weekly blood tests. In the beginning Peter only nursed twice a day to bring his phenylalanine down to a safe level. To supplement his breastfeeding, Peter drank his special formula. Every time I gave Peter a bottle, I pumped my breasts so that they were adequately stimulated and I could establish a good milk supply. I found it easiest to give Peter bottles at home. That way I could be sure to pump to make up for that feeding. I reserved the nursing for feedings away from home. It's so much easier to travel that way!

After Peter's level was brought down to a safe point, we were allowed to nurse between six and ten times a day. As time went on, the number of pumpings per day diminished to four. This was probably because my milk supply was well established. During periods of rapid growth, Peter could take quite a lot of my milk and a smaller amount of formula. When the dietician thought Peter needed more phenylalanine and asked if I could nurse more, I would respond with a strong, "Of course!" Most breastfed babies with PKU are given some supplements with phenylalanine in them: again just enough for the baby to grow. I was determined that any phenylalanine Peter got would be from my milk, not from regular formula. This meant that I had to be extra diligent about pumping so that I would have enough milk for Peter. Using a hospital-grade automatic electric breast pump and keeping up with my fluid intake helped me to produce plenty of milk for Peter. I never had to give him regular formula.

There were times when I would let Peter continue to nurse after he had "emptied" the breast (although we know the breast is never really empty because it is always producing milk). This way, we could enjoy the non-nutritive sucking that most breastfed babies and their mothers enjoy. Sometimes I would let Peter nurse immediately after I had pumped. By listening to him nurse, I could tell whether he was swallowing much milk. Gradually, I became more confident that these extra nursings were not yielding much extra milk and therefore were not elevating Peter's levels significantly.

When Peter was about nine months old, I cut the pumping back to twice a day, morning and night. What a luxury! When he was a year old, I returned the pump and relied on the phenomenon of supply and demand. Even at this point, though, when choosing Peter's foods, I always chose those very low in phenylalanine so that I could maximize the amount of breast milk he got. After all, why would I give Peter other foods when I could give him my milk? Why replace a superior food with an inferior food?

Peter nursed until the ripe old age of 18 months, when I became pregnant with our fourth child. Today he is a perfectly happy, well-adjusted, intelligent, three-year- old boy. I am so grateful for the opportunity to have nursed Peter. Yes, it was a lot of work, but I wouldn't have done it any other way. When people ask me if I have breastfed my children, I say, "Yep, every one of em!"

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