What Causes CDH? Did I Cause My Baby's Hernia?

No, you did not cause your baby’s congenital diaphragmatic hernia (CDH). The most important thing for you to know right now is that this is not your fault. Nothing you did—or didn’t do—caused your baby’s diaphragm to develop incompletely. Everyday activities, diet, exercise, stress, or lifting heavy objects do not cause this condition ^[1]. Parents often feel immense guilt upon hearing this diagnosis, but CDH is a complex structural event, not a result of your lifestyle choices.

When Does CDH Develop?

CDH occurs very early in pregnancy. The diaphragm, the muscle that separates the chest from the abdomen, forms during the first trimester. Early embryonic structures (called pleuroperitoneal folds) come together to build the connective tissue of the diaphragm ^[2][3]. If these tissues do not close completely, it leaves an opening or hole. This opening allows abdominal organs to move into the chest, which can restrict lung growth—a condition known as pulmonary hypoplasia ^[1].

This critical stage of diaphragm development is usually completed by the 8th to 10th week of gestation ^[3]. Because this happens so early, the defect forms before many women even realize they are pregnant. (Please note: Your doctors may use terms like “pleuroperitoneal folds,” but you do not need to memorize them—we only mention them to highlight how early and complex this biological process is.)

What Actually Causes CDH?

The medical community considers the exact cause of CDH to be complex and, in many cases, it remains completely unknown ^[1]. Researchers refer to the cause as multifactorial, meaning it is likely the result of multiple complex factors interacting during early fetal development rather than one single event ^[4].

When you speak with your doctors, they will likely determine if your baby’s condition is isolated (occurring by itself without other major birth defects) or non-isolated (occurring alongside other conditions). Current medical research points to a few underlying biological factors:

• Genetics: In about one-third of cases, CDH is linked to a genetic cause ^[1]. This can include various chromosomal anomalies, de novo variants (new genetic changes not inherited from either parent), or specific genetic syndromes like 1p36 deletion syndrome ^[5][6].
• Embryonic Signaling: Fetal development is guided by complex biological signals. Researchers believe that in babies with CDH, the chemical signals required for normal diaphragm and lung development (such as the retinoid signaling pathway) are disrupted ^[7][8].

Because genetics play a role in a significant portion of cases, your medical team may offer genetic testing, such as a chromosomal microarray, to help gather more information about your baby’s specific diagnosis ^[9][10]. As with all medical conditions, be sure to share your complete medical and prescription history with your doctor to rule out any rare medication interactions, though standard daily activities are not to blame.

Letting Go of the Guilt

It is completely natural to look for a reason why this happened and to question everything you did in your early weeks of pregnancy. However, CDH is a rare birth defect involving intricate cellular and genetic processes ^[1]. It is not caused by having a stressful day at work, carrying groceries, having an argument, or typical dietary choices. Focusing your energy on building the right care team—which often includes maternal-fetal medicine specialists, pediatric surgeons, and neonatologists—will be much more beneficial than carrying the burden of misplaced guilt.