File photo: In the United States, there has only been one other reported case of Legionellosis in an infant after a water birth. Picture: Reuters

Washington – Babies born during water births are at risk of contracting Legionnaires' disease, a severe and potentially life-threatening form of pneumonia.

Infections among infants born in heated birthing pools are rare. So public health officials in Maricopa County were alarmed when they learned of two cases that had taken place just months apart. They identified "numerous gaps in infection prevention" during the water births, according to a report by the Centers for Disease Control and Prevention about the Arizona investigation.

In the United States, there has only been one other reported case of Legionellosis in an infant after a water birth. That involved a Texas baby who died in 2014 just weeks after being born at home in a heated birthing pool.

The Legionella bacteria thrive in warm water and can grow in water systems such as water storage tanks or pipes. Among those at greatest risk are the elderly and people who have weakened immune systems. In 2015, about 6 000 cases of the disease were reported in the United States. Nearly 10 percent of cases are fatal. A CDC report earlier this week found that more than 500 of the total cases definitely or possibly occurred in healthcare facilities such as nursing homes or hospitals.

The first baby was delivered Jan. 6 by a midwife in a tub filled with tap water. The following day, the baby was rushed to a local emergency department in severe respiratory distress with low blood oxygen levels. Clinicians found fluid in the lungs, which can indicate pneumonia. Lab tests confirmed the infection.

The tub had been cleared with vinegar and water before being filled with tap water immediately before delivery. A new drinking water hose was used, and the mother delivered the child within an hour of entering the tub. But tap water is not sterile; Legionella can grow and spread in plumbing systems. The child did not swallow any water, but the bacteria still found its way into its lungs.

The second infant was delivered in a rented jetted Jacuzzi tub on April 5 by a different midwife. Three days after birth, the baby developed a fever of 101 degrees that lasted two days. The next day, the baby arrived in the emergency room with an even higher fever, 102.6 degrees. A chest X-ray showed cloudy spots in the lungs. The infant was admitted, and the bacterial infection was later confirmed to be Legionella.

In that case, the water in the Jacuzzi had been allowed to stay at 98 degrees F for a week, an optimal temperature for the bacteria to grow, the report said.

The health department was alerted to the second case when the same infection specialist who worked on the first baby realised that the second infant had also been delivered in a home water birth.

"She was so astute," said Tammy Sylvester, who co-manages infectious disease epidemiology at the Maricopa County health department. "She's the one who picked up on the fact that these were both at-home water births and that we need to look into this to find out what's going on."

Health officials declined to identify the hospital or the clinician who spotted the connection to protect the privacy of the patient and families.

Even though appropriate measures were used, including a new tub and new hose in the first birth, the tap water in both births wasn't treated, and that's how the infection was introduced, she said. Although the risk for infection cannot be eliminated because of the need for warm tap water, it can be reduced by running hot water through the hose for three minutes before filling the tub to clear the hose and pipes of stagnant water and sediment.

Immersion in water during labor or delivery has been popularized over the past several decades. According to the American College of Obstetricians and Gynecologists, it's hard to measure its prevalence in the United States because it hasn't been studied outside of the home or birth centers, and the information isn't recorded on birth certificates.

Undergoing the early stages of labor in a birthing pool may offer some advantages to pregnant women, ACOG noted last October in an opinion by its obstetric practice committee. However, water delivery has no proven benefit to women or newborns, and the safety and efficacy of immersion in water during delivery have not been established, ACOG said. It also noted that "rare but serious health problems in the newborn have been reported," including a higher risk of maternal and neonatal infections.

Arizona health officials have put together a tool kit about the risks for Legionella infection for women choosing water immersion for labour or birth and distributed the resources to all licensed midwives in the state and professionals working in healthcare associated infection.