Newborns are usually screened for congenital adrenal hyperplasia (CAH) with a routine blood spot test, although CAH is sometimes detected with prenatal testing. This allows lifesaving treatment to begin right away.

However, it’s still important to recognize the symptoms. Keeping an eye out for signs of CAH can help ensure your baby’s treatment is working properly.

You may know that CAH is a genetic condition that affects the adrenal glands, which are small organs on top of the kidneys that produce hormones. CAH alters the production of hormones like aldosterone, androgens, and cortisol.

About 95 percent of CAH cases are caused by 21-hydroxylase deficiency. This is an enzyme that helps make hormones called cortisol and aldosterone. There are two main types: classic CAH and nonclassic CAH. Classic CAH (which includes salt-wasting and simple-virilizing forms) is usually found at birth. Nonclassic CAH is most often diagnosed later — in childhood, adolescence, or even adulthood.

If you’re unsure what to look for or you want a handy list that’s easy to access, you’re in the right place. Here’s what to know about possible CAH symptoms in your newborn.

1. Vomiting

Vomiting may occur in newborns with CAH, but it can be hard to tell the difference between vomiting and normal spit-up. Spit-up usually comes out easily with a burp, while vomit tends to be more forceful. This difference can be tricky to spot, especially for first-time parents or if you haven’t seen a baby spit up before. If you’re unsure, reach out for guidance from your pediatrician or pediatric endocrinology team (a group of doctors who specialize in hormone-related conditions in children).

2. Skin Darkening

Hyperpigmentation (darkening of the skin) is a common sign of CAH in newborns, but it can be hard to recognize. It may be seen all over the body, including on the genitalia, nipples, gums, or in skin creases. If your baby’s skin appears unusually dark in some areas, see your pediatrician or pediatric endocrinologist to find out what’s going on.

3. Dehydration

Vomiting and the resulting lack of food can lead to dehydration. If untreated, CAH can also cause your baby to lose too much sodium and water through their urine, which can result in dangerously low fluid levels.

A dehydrated newborn may have dry eyes, dry skin, and a dry mouth. The soft spot in the center of their skull might look sunken. If you press on a baby’s thumbnail until it turns pale, it should return to its original color again quickly — if it takes more than two seconds, this may be a sign of dehydration. These warning signs mean you should take your baby to a healthcare provider right away.

4. Poor Eating

Newborns with untreated CAH may not eat very much or very well. Poor feeding can happen whether your baby is breastfed or given formula. There are several reasons a newborn might not eat well. It may be related to the same discomfort that causes vomiting. If your child isn’t eating well after a CAH diagnosis or has other symptoms from this list, talk to a doctor to find out what to do next.

5. Variations in Genital Appearance

Some newborns with classic CAH may have genitalia that look different from what is typically expected for their age and gender. Female babies have ovaries, a uterus, and fallopian tubes internally, but may have external genitalia that look different from typical female anatomy. For example, the labia may resemble a scrotum because they might appear partly closed, the clitoris may be enlarged and look more like a penis, or there may be one opening instead of two for the urethra (where you urinate) and vagina. Male babies may have a penis that is larger than expected at birth.

These changes are present at birth with classic CAH. This is one reason doctors and nurses check a newborn’s genitals after birth. If they notice any changes, they can make sure the infant gets the tests they need to figure out what is going on.

6. Low Blood Sugar

CAH may also cause low blood sugar levels in your newborn. It may take a blood test to figure out if your newborn has low blood sugar, because some babies won’t have any symptoms. However, a baby with low blood sugar may experience shaking or tremors, bluish skin, issues staying warm, breathing problems, floppy muscles, irritability, and difficulty eating. If your newborn shows any signs that their blood sugar is too low, seek care immediately.

7. Low Blood Sodium

A newborn with CAH may also have very low sodium (salt) levels in their blood. This happens because their body can’t produce the hormones needed to control sodium levels. Low sodium may cause vomiting, seizures, or unusual muscle weakness. Sodium levels are usually measured with a blood test, which your baby’s pediatric or endocrinology team will order if they suspect a problem.

8. Weight Loss

Weight loss is also common in babies diagnosed with CAH. This is beyond the typical weight loss that babies experience in the first few days after birth. If your baby doesn’t regain this weight within two weeks or continues to lose weight, talk to their healthcare team right away. If your baby is being treated for CAH, they may need additional treatment. If your baby hasn’t been diagnosed, it’s time to run some tests.

9. Adrenal Crisis

Some infants with CAH can develop an adrenal crisis, which happens when very low hormone levels cause blood pressure to drop so much that the brain and other organs don’t get enough blood flow. An adrenal crisis is a medical emergency. A baby experiencing an adrenal crisis may have a very rapid heart rate, be extremely irritable, or go into a coma. If you suspect your baby is in an adrenal crisis or headed that way, call for emergency help immediately. An adrenal crisis is life-threatening and needs to be treated as quickly as possible.

10. High Blood Acid Levels

Metabolic acidosis (high levels of blood acid) is usually diagnosed with a blood test. Your newborn may have a very fast heart rate, have changes in their breathing, seem weaker than usual, have breath that smells fruity or sweet, stop eating, or start vomiting. All of these are signs that it’s time to get medical care as soon as possible to help your baby feel better.

Early Support Is Key

Recognizing CAH symptoms early can make a big difference in your baby’s health. If you notice anything concerning, talk to your doctor as soon as possible. With the right care and monitoring, babies with CAH can grow and thrive. Early treatment helps manage symptoms and supports healthy development.

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