Does a Baby's Positive SPCD Screen Mean the Mother Has It?

Yes, it is entirely possible—and in fact, it is a very common way for mothers to be diagnosed with Systemic Primary Carnitine Deficiency (SPCD). You may also see this condition called Primary Carnitine Deficiency (PCD) or Carnitine Uptake Defect (CUD).

When a newborn screening comes back positive for low free carnitine (often listed as C0 on the test results), it does not automatically mean the baby has SPCD ^[1][2]. Because a baby gets their carnitine from their mother during pregnancy, the baby’s carnitine levels right after birth are a direct reflection of the mother’s levels ^[1][2]. If the mother has undiagnosed SPCD, her carnitine levels will be low, meaning she could not pass enough carnitine to her baby through the placenta ^[1][3].

As a result, the baby will flag positive on the newborn screen because of this temporary low supply, even if the baby does not actually have the disease ^[1].

The Placenta Connection

Carnitine is an essential nutrient that helps the body turn fat into energy. During pregnancy, the baby relies completely on the mother for their supply of carnitine. The placenta acts as a bridge, actively transporting carnitine from the mother’s blood into the baby’s blood ^[3][4].

If a mother has SPCD, her body has trouble holding onto carnitine, causing her blood levels to drop significantly ^[2]. Because she does not have enough carnitine circulating in her own blood, the placenta cannot transfer an adequate amount to the baby ^[1][2].

Is the Baby Healthy?

In many of these cases, the baby is perfectly healthy. It is very common for the baby to be just a “carrier” of the SPCD gene mutation (the SLC22A5 gene) ^[1]. Being a carrier means the baby inherited one mutated gene from the mother, but assuming they inherited a normal gene from the father, they have enough functional genes to process carnitine normally ^[1]. Once the baby starts eating and producing their own carnitine, their levels will typically rise to normal.

However, because the baby’s levels were low at birth, the newborn screen will still trigger a “positive” or “abnormal” result, often referred to as a false-positive for the infant ^[1][5]. This result mandates that doctors test the mother’s blood to see if maternal SPCD is the true cause, and also necessitates re-testing the baby to confirm whether they actually have the condition or are just a carrier ^[1][6].

Why Was the Mother Never Diagnosed?

It is completely normal to wonder how you could have a genetic metabolic condition and never know it. Many adults with SPCD are completely asymptomatic, meaning they show absolutely no signs of the disease ^[7][8].

However, pregnancy places immense physical and metabolic stress on the body. A maternal diagnosis of SPCD triggered by a baby’s newborn screen is actually a lifesaving discovery in disguise ^[1]. If left completely untreated, adults with SPCD are at a higher risk for sudden heart issues (like cardiomyopathy, a weakening of the heart muscle) or dangerous drops in energy during illness or fasting ^[7][9].

What to Do While You Wait for Results

While you are waiting for follow-up blood and genetic tests, there are a few important steps you can take to protect yourself and your baby:

• Avoid Fasting: The major danger with SPCD is that the body struggles to use fat for energy when it runs out of food. It is vital to avoid skipping meals. As a new mother, it is incredibly easy to forget to eat due to exhaustion, but you must eat regular meals and stay hydrated to prevent dangerous energy drops ^[10][11].
• Discuss Feeding Plans: You will need to discuss infant feeding with your pediatrician right away. You should specifically ask if your breastmilk alone is sufficient for now, or if your baby needs an L-carnitine supplement or formula while you wait for both of your test results.
• Monitor Your Energy: It is notoriously difficult to tell the difference between “normal postpartum exhaustion” and fatigue caused by SPCD. If you feel extreme weakness, confusion, or heart palpitations, contact your medical team immediately.

Next Steps for the Family

When a baby’s newborn screen suggests the mother might have SPCD, doctors will quickly recommend a few follow-up steps:

• Maternal Blood Test: The mother’s blood will be drawn to check her free carnitine (C0) and total carnitine levels. If they are very low, it strongly points to maternal SPCD ^[1][12].
• Genetic Testing: Both the mother and the baby may undergo genetic testing to look for mutations in the SLC22A5 gene, which confirms the diagnosis and determines if the baby is a carrier or affected ^[1][6].
• L-carnitine Supplementation: If the mother is diagnosed, she will likely be prescribed lifelong L-carnitine supplements. This simple, highly effective treatment prevents severe complications for the mother and makes future pregnancies safer ^[9][13].