The Danish team used information from the Danish National Newborn Cohort (DNBC), which collected data on the health of newborn babies from 1996 to 2002. The study included the medical records of more than 32.6 thousand children and the results of telephone interviews with their mothers, who were questioned at 16 and 30 weeks of pregnancy, immediately after childbirth, and also after 11 years.
In this sample, over 5.5 thousand children were born to women who took antibiotics during pregnancy. Over the eleven-year observation period, bronchial asthma was detected in more than 4.2 thousand young patients. It is noteworthy that the risk of developing this disease was associated with taking antibiotics only in the second half of pregnancy. Children whose mothers took antibacterial drugs in the first trimester did not have such health effects.
In addition, a link between prenatal antibiotic exposure and bronchial asthma has been found primarily in naturally born babies rather than by caesarean section.
Since we are talking about observational research, scientists cannot explain this phenomenon. They suggest that antibiotics change the composition of the gut microbiota of the expectant mother, which is passed on to the child during natural childbirth. Previous studies have shown that this microbiota influences the formation of the immunity of children and may play a role in their predisposition to certain diseases.
Previously, US researchers have identified a dose-dependent relationship between antibiotic therapy in infancy and the development of childhood asthma, regardless of the type of antibiotic administered or the timing of its administration. Moreover, the likelihood of asthma increases with each additional antibiotic prescription.
Scientists analyzed information on the prescription of antibiotics for 152.6 thousand full-term babies born in the period from 1995 to 2003 as a result of a singleton pregnancy, with normal weight and otherwise healthy.
According to the findings, 79% of infants under 1 year of age had at least one antibiotic prescription. With each additional prescription of antibacterial drugs, the risk of developing asthma increased by 20%.