Perinatal smoke exposure linked to GER

Michael G Burke, MD

Infants who are exposed to tobacco smoke during their mothers’ pregnancy or after birth are at increased risk of gastroesophageal reflux (GER), especially of events with bolus movement detected by impedance (GER-imp), according to a French study in 31 neonates referred to a medical center for investigation of suspected GER.

Participants underwent synchronized MII-pH monitoring and synchronized 8- to 12-hour polysomnography. Investigators estimated infants’ exposure to tobacco smoke using a urine cotinine assay. (All the infants were formula fed, which ruled out being exposed to tobacco via their mother’s milk.) Infants with a urine cotinine level below the detection threshold of 1 ng/mL^-1 were considered the control group (10 neonates), and those with a urine cotinine level greater than 1 ng/mL^-1 constituted the smoking-exposed group (21 neonates).

Investigators also determined the total number, frequency, and mean duration of GER-pH (reflux events detected by the pH electrode only) and GER-imp events. In addition, mothers completed a questionnaire about how many cigarettes they smoked during and after pregnancy and the smoking habits of other household members.

A total of 923 GER events were reported during 304 hours of recording time. All the GER variables were greater in the smoking-exposed group than in the non-exposed group. Only the differences between the smoking-exposed and control groups in the median number and frequency of GER-imp events were statistically significant, however: 29 versus 12 for the median number and 2.6 versus 1.0 events per hour for frequency. Notably, the proportion of GER-imp events with retrograde bolus migration to the most proximate segment was significantly higher in the smoking-exposed group (83%) than in the unexposed group (41%).

Finally, the observed GER pattern associated with smoking exposure was particularly obvious during rapid eye movement (REM) sleep, with the time spent in GER-imp and median number of GER-imp events 2-fold greater in the smoking-exposed group than in the nonexposed group during REM sleep (Djeddi D, et al. J Pediatr. 2018;201:147-153).

Thoughts from Dr Burke

This is a small but important study. In explaining their findings of worsened GER in smoke-exposed infants, the authors cite work in adult smokers showing decreased lower esophageal sphincter tone after exposure to nicotine. They acknowledge that their findings need to be confirmed on a larger scale, but in the meantime, I am going to be sure to seek a history of smoke exposure when seeing babies with significant GER.