The authors respond:
We read with great interest the recent letter by Zouein and Bourjeily1 commenting on our article on “Sleep patterns in late pregnancy and risk of preterm birth and fetal growth restriction.”2 The main point in our discussion was that there exists little and controversial epidemiologic evidence on sleep behaviors during pregnancy and their association with birth outcomes. Zouein and Bourjeily agree with us on this. They mention that we erroneously quoted the study by Bourjeily et al3 as having similar findings. We stated that the risk ratio of 2 that we found was similar to the odds ratio of 1.9 reported by Bourjeily et al. Although that estimate was not statistically significant, this seems a reasonable statement to us.
Zouein and Bourjeily1 are right in stressing that the prevalence of severe snoring in our study population (14% occasionally snorers and 4% severe snores) is lower than in other studies. We are aware of the issues, and we should have discussed it in our paper. The prevalence of obesity was twice as high in the study by Bourjeily et al (22% women had a prepregnancy BMI ≥30) compared with our cohort (11% women had a prepregnancy BMI ≥30; prepregnancy mean BMI = 24.2 [SD = 4.8]), and this could partially explain the observed differences. Other sociocultural, nutritional (for example the high adherence to Mediterranean diet),4 and environmental differences in Crete could also contribute to the low prevalence of severe snoring. Future longitudinal studies are needed to confirm these findings, to better understand the complex underlying processes, and to develop preventive-care strategies based on sleep-quality improvement during pregnancy.
Department of Social Medicine
University of Crete
Centre for Research in Environmental Epidemiology (CREAL)
National School of Public Health
1. Zouein E, Bourjeily G. Sleep patterns in pregnancy and fetal growth [letter]. Epidemiology 2012;223:356.
2. Micheli K, Komninos I, Bagkeris E, et al.. Sleep patterns in late pregnancy and risk of preterm birth and fetal growth restriction. Epidemiology. 2011;22:738–744.
3. Bourjeily G, Raker CA, Chalhoub M, Miller MA. Pregnancy and fetal outcomes of symptoms of sleep-disordered breathing. Eur Respir J. 2010;36:849–855.
4. Chatzi L, Mendez M, Garcia R, et al.. Mediterranean diet adherence during pregnancy and fetal growth: INMA (Spain) and RHEA (Greece) mother-child cohort studies. Br J Nutr. 2011;29:1–11.