C-section not tied to childhood asthma

In theory, whether a child is born by Cesarean section or in the normal way via the birth canal could affect his or her chances of developing asthma later in life - but that notion apparently does not hold up in reality.

The mode of delivery at birth appears to have no bearing on the subsequent development of Asthma, researchers report.

The development of allergies and Asthma is thought to be influenced by the type of infections a child is exposed to very early in life, which in turn sets the immune system to respond normally or over-sensitively to allergens. The so-called ‘hygiene hypothesis’ holds that children who are overly protected against bacteria tend to develop allergies, because they need the exposure to develop a balanced immune system.

“Bacterial colonization of the gut in newborns delivered by Cesarean section differs from that in newborns born by vaginal delivery,” lead investigator Dr. Young J. Juhn told Reuters Health. This may influence the development of allergies.

A C-section, also called a cesarean section, is the delivery of a baby through a surgical abdominal incision.

A C-section delivery is performed when a vaginal birth is not possible or is not safe for the mother or child.

Surgery is usually done while the woman is awake but anesthetized from the chest to the legs by epidural or spinal anesthesia. An incision is made across the abdomen just above the pubic area. The uterus is opened, the amniotic fluid is drained, and the baby is delivered.

As reported in the Journal of Allergy and Clinical Immunology, Juhn and colleagues examined data for more than 7000 children - 10 percent of whom were delivered by Cesarean section - to see if different bacterial exposure influenced the risk of Asthma development or wheezing.

Over 7 years, the asthma occurred at a rate of 3.2 to 5.7 percent in the cesarean group and 2.6 to 6.7 percent in the vaginal delivery group. The differences were not significant from a statistical standpoint.

Asthma is an inflammatory disorder of the airways, characterized by periodic attacks of wheezing, shortness of breath, chest tightness, and coughing.

Causes, incidence, and risk factors
Asthma is a disease in which inflammation of the airways causes airflow into and out of the lungs to be restricted. When an asthma attack occurs, the muscles of the bronchial tree become tight and the lining of the air passages swells, reducing airflow and producing the characteristic wheezing sound. Mucus production is increased.

Most people with asthma have periodic wheezing attacks separated by symptom-free periods. Some asthmatics have chronic shortness of breath with episodes of increased shortness of breath. Other asthmatics may have cough as their predominant symptom. Asthma attacks can last minutes to days, and can become dangerous if the airflow becomes severely restricted.

The investigators conclude, “Either the underlying assumption of the hygiene hypothesis in assessing the influence of microbial organisms on development of (allergies) may be too simplistic conceptually and methodologically, or the influence of microbial organisms ... may be weaker than what has been reported.”

SOURCE: Journal of Allergy and Clinical Immunology, September 2005.

Provided by ArmMed Media
Revision date: July 6, 2011
Last revised: by Amalia K. Gagarina, M.S., R.D.