Does My Baby Need Calcium Monitoring if I Have FHH1?

Yes, your baby may need some special attention and a few blood tests in the hospital right after they are born. Because you have Familial Hypocalciuric Hypercalcemia Type 1 (FHH1), your baby’s calcium levels will need to be monitored in their first few days of life to ensure they do not drop too low.

Why does my baby need to be monitored?

During pregnancy, your baby gets all their calcium from you through the placenta. Because your FHH1 causes you to have slightly higher-than-average blood calcium levels, your baby is also exposed to those higher levels while in the womb ^[1].

In response to this extra calcium, your baby’s developing parathyroid glands (the tiny glands in the neck that control calcium levels) essentially go to sleep, or become suppressed ^[1][2]. When your baby is born and is no longer receiving your calcium supply, their own parathyroid glands may take a few days to a week to “wake up” and start working properly ^[3][2]. Until they do, the baby’s calcium levels may drop, causing a condition known as transient neonatal hypocalcemia (temporary low blood calcium in a newborn) ^[1]. Because FHH1 typically causes only mild calcium elevation in the mother, significant drops in the baby’s calcium are not guaranteed, but monitoring is essential to be safe.

What will the hospital do?

Your pediatric care team will test your baby’s blood calcium levels to catch any drops early ^[1][4]. This is typically done by testing the umbilical cord blood at birth, followed by heel pricks around 24 and 48 hours of life.

If calcium levels become too low, babies can develop physical symptoms such as:

• Jitteriness or trembling
• Muscle twitching
• In more severe, unchecked cases, seizures ^[5][6]

By catching low calcium quickly through routine blood tests, your baby’s doctors can manage it effectively and prevent these symptoms from occurring ^[4].

Is this condition dangerous?

While the idea of your newborn having low calcium can be scary, it is important to know that transient neonatal hypocalcemia is temporary and highly treatable ^[1]. If your baby’s calcium drops, the hospital can give them calcium supplements (either orally or through an IV) until their parathyroid glands begin producing enough hormone on their own ^[7][1]. If IV calcium is required, your baby may need to be admitted to a special care nursery or the Neonatal Intensive Care Unit (NICU) so their heart rate and the IV site can be monitored safely ^[7].

A Vital Safety Note: What if my partner also has high calcium?

If your baby’s other biological parent also has FHH1 or a family history of unexplained high calcium, it is critical to inform your obstetrician and pediatric team before birth. If a baby inherits a mutated CASR gene from both parents, they are at risk for a rare but life-threatening emergency called Neonatal Severe Primary Hyperparathyroidism (NSHPT) ^[2][8]. This requires immediate, specialized medical intervention.

Can I safely breastfeed?

Yes, most mothers with FHH1 can safely breastfeed. The temporary low calcium your baby may experience is caused by the sudden loss of the placenta’s high-calcium supply at birth, not by your breastmilk ^[1][2]. You should discuss your breastfeeding goals with your pediatrician, who will ensure your baby’s nutritional and calcium needs are fully supported while you nurse.

What about the FHH1 gene and the future?

Depending on whether your baby inherited the genetic mutation for FHH1 from you, their long-term calcium levels could be affected. If they inherited the gene, they might eventually show slightly elevated calcium levels, just like you ^[1][2]. Remember that FHH1 is generally a benign condition, and most people live entirely normal lives without ever needing treatment ^[9]. Your pediatrician will likely recommend genetic testing or continued calcium monitoring in early childhood to determine if they inherited the condition ^[1][10].