Maternal snoring during pregnancy is associated with enhanced fetal erythropoiesis--a preliminary study

Snoring is common among pregnant women and early reports suggest that it may bear a risk to the fetus. Increased fetal erythropoiesis manifested by elevated circulating nucleated red blood cells (nRBCs) has been found in complicated pregnancies involving fetal hypoxia. Both erythropoietin (EPO) and interleukin-6 (IL-6) mediate elevation of circulating nRBCs. The intermittent hypoxia and systemic inflammation elicited by sleep-disordered breathing (SDB) could affect fetal erythropoiesis during pregnancy. We hypothesized that maternal snoring will result in increased levels of fetal circulating nRBCs via increased concentrations of EPO, IL-6, or both.

Women of singleton uncomplicated full-term pregnancies were recruited during labor and completed a designated questionnaire. Umbilical cord blood was collected immediately after birth and analyzed for nRBCs, plasma EPO and plasma IL-6 concentrations. Newborn data were retrieved from medical records.

One hundred and twenty-two women were recruited. Thirty-nine percent of women reported habitual snoring during pregnancy. Cord blood levels of circulating nRBCs, EPO and IL-6 were significantly elevated in habitual snorers compared with non-snorers (p = 0.03, 0.005 and 0.01; respectively). No differences in maternal characteristics or newborn crude outcomes were found.

Maternal snoring during pregnancy is associated with enhanced fetal erythropoiesis manifested by increased cord blood levels of nRBCs, EPO and IL-6. This provides preliminary evidence that maternal snoring is associated with subtle alterations in markers of fetal well being.