When I was 36 weeks pregnant with my second child, Anna, my obstetrician noted that my fetus had a disproportionately small head, or microcephaly—a condition now commonly known because of its association with the Zika virus. “We’ll just have to wait and see,” he said, meaning we’ll look for answers if the baby is affected at birth. But when my daughter was born, there were no answers then either.

Anna was silent when the midwife held her up. She was only five pounds. And then she failed her newborn hearing tests. The rotating pediatricians came in and out of the room, puzzled but silent, and they discharged us without any further testing. I had an intuitive feeling we were missing something, but I didn’t know which test to request.

When Anna was ten days old, we went to our family’s pediatrician. Noting that she was small for gestational age and had a potential hearing loss, he said, “I think we should test her for a little-known but common virus that can cause issues during pregnancy. That disease is called cytomegalovirus, or CMV.” And that’s when my research began.

The first thing I saw was the striking spectrum of CMV: babies infected in utero (who have congenital CMV, or CMV from birth) can be totally fine or they can be stillborn. In fact, I read that CMV is the leading pathogen linked to stillborn babies. In between these jarring opposites, a child with congenital CMV could also have hearing loss, vision loss, cerebral palsy, epilepsy, behavioral challenges, and/or autism—most of which would not even be linked back to CMV, since less than 10 percent of babies with CMV are ever diagnosed.

Next, a link on the American Academy of Pediatrics website made my jaw drop: unlike Zika, an infection spread through mosquitos, CMV is transmitted primarily through the saliva of toddlers—and, the AAP study revealed, a young child can be shedding CMV for up to 40 months. Because I’d had a toddler at home when I was pregnant, I wondered how likely it was that she’d been carrying CMV. The CDC’s webpage on CMV held the shocking answer: one out of three toddlers is contagious with CMV.

While I’d been warned about toxoplasmosis—the kitty litter disease, which affects about 1 in 10,000 babies—I know that CMV had never been mentioned to me during pregnancy, even though it affects a much more substantial amount of children annually. One in 200 babies, or 30,000 to 40,000 a year in the United States, are born with CMV—6,000 to 8,000 of whom will experience lifelong impairments. These affected babies outnumber the babies disabled by any other congenital disease.

I was certain I hadn’t learned about CMV during pregnancy because if I’d learned the simple prevention measures to reduce my risk (not finishing my toddler’s meals while pregnant; not kissing her on the lips; washing my hands thoroughly after changing her diaper or wiping her nose), I would have implemented these easy, healthy changes to save my next child from potentially life-threatening medical complications. When I looked back to the prenatal packets I’d received during both of my pregnancies, as I suspected, there was no mention of congenital CMV.

In this dizzying whirlwind of what seemed like a systemic and disabling silence, I wondered how this could be. How could 90 percent of the population not know about the leading cause of birth defects, nongenetic deafness, and developmental delays in the United States?

It didn’t take me long to find part of the answer. ACOG, the American Congress of Obstetricians and Gynecologists, recommends that OBs in the U.S. not counsel women about CMV, essentially stating that washing our hands more around our toddlers would be “impractical or burdensome” during pregnancy. When I looked to the bottom of this document, which was published in 2015, there was no actual study conducted on anyone pregnant to verify this claim.

Historically, CMV is not the first disease doctors have withheld from their patients under the guise of caring for the patient’s emotional well-being. As recently as 1961, 90 percent of physicians preferred not to disclose cancer diagnoses to their patients, believing that it would too greatly upset the sick person. This was the case even though a study conducted a decade earlier, in 1950, had shown that the vast majority of patients desired to know the truth.

In the field of medicine, there’s a term for this well-intentioned omission of information. “Benevolent deception” describes the silence I was facing with CMV: ACOG—and many OBs I have since interviewed personally—believe that worrying people of childbearing age about CMV will affect them too negatively for them to know the truth. This is despite the fact that studies have shown that 90 percent of women in the U.S. and in other countries want to know about CMV. And other studies, both here and abroad, have shown a drastic reduction in the risk of contracting CMV if people know how dangerous it is during pregnancy and that toddlers are the primary vector of the disease.

The American Medical Association actually bans the usage of benevolent deception—otherwise known as “the therapeutic privilege”—in medical practice today. And yet, my child would end up testing positive for congenital CMV, we found out a month later she was profoundly deaf, and she would go on to have gross motor delays from a disease I may have prevented through knowledge alone.

While it’s true that we don’t have all the answers for CMV, including a reliable treatment for it during pregnancy, we do have the ability to test newborns and treat them immediately after they’re born. But without having the conversation about CMV during pregnancy and without our doctors being more educated about the disease, these newborns will continue to go undiagnosed and untreated, with their disease unfairly dismissed.

In order to dispel the myths about CMV, I’ve spent the last eight years researching and writing a book about my daughter’s disease. Today, Anna can articulate that CMV is the reason she’s deaf. But until all people planning to have a baby know the name of her disease, we do not have benevolence in obstetrical care; we have ongoing deception.

Megan Nix is a writer and author of Remedies for Sorrow: An Extraordinary Child, a Secret Kept from Pregnant Women, and a Mother’s Pursuit of the Truth.