1 in 3850 babies have diaphragmatic hernia, a birth defect where the incompletely formed diaphragm allows the stomach, liver, and other abdominal organs to move into the chest. The overcrowded lungs cannot grow, and may be too small to support the baby even if the diaphragm is surgically repaired.

DETECTION AND TREATMENT

In the most common type of diaphragmatic defects, the muscular sheet separating the chest and abdominal cavities fails to close normally by 4-5 weeks after conception. About 80% of defects are on the left side.

Diaphragmatic hernia is generally diagnosed soon after birth in babies with severe breathing difficulties, but can be detected on prenatal ultrasound. Although the hernia can be surgically repaired (sometimes even with experimental prenatal surgery), babies often die because their lungs are too small or because they have additional birth defects—only 53% survive to age 1. The lifetime cost for medical treatment, educational services and lost productivity averages more than $250,000.

ASSOCIATED BIRTH DEFECTS LOWER SURVIVAL

The California Birth Defects Monitoring Program reviewed 631 cases of diaphragmatic hernia from over 2.2 million births. We found:

	The mother's age, race and number of previous births did not alter risks. Twins were more likely than single births to have diaphragmatic hernia.
	About half of affected infants had other birth defects, with heart defects the most common structural problem. Several infants had recognized birth defects patterns (such as the Cornelia de Lange syndrome and Fryns syndrome).
	7% of affected babies had a chromosome abnormality. Trisomy 18 was the most common but Down syndrome, trisomy 13 and other abnormalities were also seen.
	Babies with additional birth defects were far more likely to die: 68% of isolated cases were alive at 1 year compared to 42% with other birth defects and only 8% of the chromosomal cases. 89% of deaths occurred in the first month.
	About 5% of cases were stillborn; most had associated birth defects or chromosome abnormalities.

RECURRENCE RISK LOW

An earlier study of diaphragmatic hernia in California found that brothers and sisters of affected infants were no more likely than other children to have birth defects. Only 1% of families had previous children with diaphragmatic hernia.